JP7530593B2 - Electron transport or injection material containing alkyl-substituted polycyclic aromatic compounds - Google Patents

Description

The present invention relates to an electron transport material or electron injection material (hereinafter collectively referred to as "electron transport material") containing an alkyl-substituted polycyclic aromatic compound and its polymer (hereinafter collectively referred to as "polycyclic aromatic compound"), and an organic electroluminescent device, display device, and lighting device using the same. In this specification, "organic electroluminescent device" may be referred to as "organic EL device" or simply as "device".

Display devices using electroluminescent light-emitting elements have been extensively studied because they can be made thin and energy-efficient, and organic electroluminescent devices made from organic materials have been actively studied because they can be easily made large and lightweight. In particular, there has been active research into the development of organic materials that have the luminescence properties of blue, one of the three primary colors of light, and organic materials that have the ability to transport charges such as holes and electrons (potential to become semiconductors or superconductors), regardless of whether they are polymeric or low-molecular-weight compounds.

An organic EL element has a structure consisting of a pair of electrodes consisting of an anode and a cathode, and one or more layers containing organic compounds that are disposed between the pair of electrodes. The layers containing organic compounds include a light-emitting layer and a charge transport/injection layer that transports or injects charges such as holes and electrons, and various organic materials suitable for these layers have been developed.

As materials for the light-emitting layer, for example, benzofluorene-based compounds have been developed (WO 2004/061047). As hole-transporting materials, for example, triphenylamine-based compounds have been developed (JP 2001-172232 A). As electron-transporting materials, for example, anthracene-based compounds have been developed (JP 2005-170911 A).

In recent years, a material that improves triphenylamine derivatives has also been reported as a material for use in organic electroluminescence devices and organic thin-film solar cells (WO 2012/118164). This material is characterized by its improved planarity, which is achieved by linking the aromatic rings that make up the triphenylamine, based on N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), which has already been put to practical use. This document evaluates the charge transport properties of, for example, NO-linked compounds (compound 1 on page 63), but does not describe how to manufacture materials other than NO-linked compounds. Furthermore, since the electronic state of the entire compound differs depending on the linked element, the properties obtained from materials other than NO-linked compounds are not yet known. There are other examples of such compounds (WO 2011/107186). For example, compounds with a conjugated structure that has a large triplet exciton energy (T1) can emit phosphorescence with a shorter wavelength, making them useful as materials for blue light-emitting layers. In addition, compounds having a novel conjugated structure with a large T1 are also required as electron transport materials and hole transport materials that sandwich the light emitting layer.

International Publication No. 2004/061047 JP 2001-172232 A JP 2005-170911 A International Publication No. 2012/118164 International Publication No. 2011/107186 International Publication No. 2015/102118

As mentioned above, various materials have been developed for use in organic EL elements, but in order to increase the options for materials for organic EL elements, there is a need to develop materials made of compounds that are different from conventional ones. In particular, the organic EL characteristics obtained from materials other than the NO-linked compounds reported in Patent Documents 1 to 4, and the methods for producing them, are not yet known.

Furthermore, Patent Document 6 reports a polycyclic aromatic compound containing boron and an organic EL device using the same, but in order to further improve the device characteristics, there is a demand for electron transport materials that can improve the luminous efficiency and device lifespan.

As a result of intensive research to solve the above problems, the present inventors have found that an excellent organic EL element can be obtained by, for example, constructing an organic EL element by disposing, between a pair of electrodes, an electron transport layer containing a polycyclic aromatic compound in which an alkyl group has been introduced at a specific position (specifically, the ortho position), and have thus completed the present invention. That is, the present invention provides an electron transport material for an organic EL element that contains the following alkyl-substituted polycyclic aromatic compound or a polymer thereof:

In this specification, the chemical structure or the substituent may be expressed by the number of carbon atoms, but the number of carbon atoms in the case where a substituent is substituted for the chemical structure or where a substituent is further substituted for the substituent means the number of carbon atoms in each of the chemical structure and the substituent, and does not mean the total number of carbon atoms in the chemical structure and the substituent, or the total number of carbon atoms in the substituent and the substituent. For example, "substituent B of carbon number Y substituted with substituent A of carbon number X" means that "substituent B of carbon number Y" is substituted with "substituent A of carbon number X", and the carbon number Y is not the total number of carbon atoms of the substituent A and the substituent B. Also, for example, "substituent B of carbon number Y substituted with substituent A" means that "substituent B of carbon number Y" is substituted with "substituent A (with no carbon number limit)", and the carbon number Y is not the total number of carbon atoms of the substituent A and the substituent B.

（上記式（１）中、
Ａ環、Ｂ環およびＣ環は、それぞれ独立して、アリール環またはヘテロアリール環であり、これらの環における少なくとも１つの水素は置換されていてもよく、
Ｙ^１は、Ｂ、Ｐ、Ｐ＝Ｏ、Ｐ＝Ｓ、Ａｌ、Ｇａ、Ａｓ、Ｓｉ－ＲまたはＧｅ－Ｒであり、前記Ｓｉ－ＲおよびＧｅ－ＲのＲは、アリール、アルキルまたはシクロアルキルであり、
Ｘ^１およびＸ^２は、それぞれ独立して、＞Ｏ、＞Ｎ－Ｒ、＞Ｃ（－Ｒ）_２、＞Ｓまたは＞Ｓｅであり、前記＞Ｎ－ＲのＲは、置換されていてもよいアリール、置換されていてもよいヘテロアリール、置換されていてもよいアルキルまたは置換されていてもよいシクロアルキルであり、前記＞Ｃ（－Ｒ）_２のＲは、水素、置換されていてもよいアリール、置換されていてもよいアルキルまたは置換されていてもよいシクロアルキルであり、また、前記＞Ｎ－ＲのＲおよび／または前記＞Ｃ（－Ｒ）_２のＲは連結基または単結合により前記Ａ環、Ｂ環およびＣ環のうちの少なくとも１つと結合していてもよく、
式（１）で表される化合物または構造における少なくとも１つの水素は、重水素、シアノまたはハロゲンで置換されていてもよく、そして、
式（１）で表される化合物または構造における少なくとも１つの水素は上記一般式（ｏＲ）で表される基で置換されており、
上記式（ｏＲ）中、Ｒ^２１はアルキルであり、Ｒ^２２～Ｒ^２５は、それぞれ独立して、水素、アリール、ヘテロアリール、アルキルまたはシクロアルキルであり、Ｒ^２２～Ｒ^２５のうちの隣接する基同士が結合してベンゼン環と共にアリール環またはヘテロアリール環を形成していてもよく、形成された環における少なくとも１つの水素は、アリール、ヘテロアリール、アルキルまたはシクロアルキルで置換されていてもよく、上記式（ｏＲ）で表される基は＊において上記式（１）で表される化合物または構造における少なくとも１つの水素と置換する。） Item 1.
An electron transport material or electron injection material comprising a polycyclic aromatic compound represented by the following general formula (1) or a polymer of a polycyclic aromatic compound having a plurality of structures represented by the following general formula (1):

(In the above formula (1),
ring A, ring B and ring C are each independently an aryl ring or a heteroaryl ring, and at least one hydrogen atom in these rings may be substituted;
^Y1 is B, P, P=O, P=S, Al, Ga, As, Si-R or Ge-R, wherein R in the Si-R and Ge-R is aryl, alkyl or cycloalkyl;
^X1 and ^X2 are each independently >O, >N-R, >C(-R) ₂ , >S or >Se, R of the >N-R is an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted alkyl or an optionally substituted cycloalkyl, R of the >C(-R) ₂ is a hydrogen, an optionally substituted aryl, an optionally substituted alkyl or an optionally substituted cycloalkyl, and R of the >N-R and/or R of the >C(-R) ₂ may be bonded to at least one of the A ring, the B ring and the C ring via a linking group or a single bond;
At least one hydrogen atom in the compound or structure represented by formula (1) may be replaced with deuterium, cyano or halogen; and
At least one hydrogen atom in the compound or structure represented by formula (1) is substituted with a group represented by the above general formula (oR),
In the above formula (oR), R ²¹ is alkyl, R ²² to R ²⁵ are each independently hydrogen, aryl, heteroaryl, alkyl or cycloalkyl, adjacent groups among R ²² to R ²⁵ may be bonded to each other to form an aryl ring or heteroaryl ring together with a benzene ring, at least one hydrogen atom in the formed ring may be substituted with an aryl, heteroaryl, alkyl or cycloalkyl, and the group represented by the above formula (oR) is substituted at * with at least one hydrogen atom in the compound or structure represented by the above formula (1).

Item 2.
In the above formula (1),
ring A, ring B and ring C are each independently an aryl ring or a heteroaryl ring, at least one hydrogen atom in these rings may be substituted with a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted alkoxy or a substituted or unsubstituted aryloxy, and these rings have a 5- or 6-membered ring that shares a bond with the central fused bicyclic structure of the above formula composed of Y ¹ , X ¹ and X ² ,
^Y1 is B, P, P=O, P=S, Al, Ga, As, Si-R or Ge-R, wherein R in the Si-R and Ge-R is aryl, alkyl or cycloalkyl;
X ¹ and X ² are each independently >O, >N-R, >C(-R) ₂ , >S or >Se, R of the >N-R is aryl which may be substituted with alkyl or cycloalkyl, heteroaryl which may be substituted with alkyl or cycloalkyl, alkyl or cycloalkyl, R of the >C(-R) ₂ is hydrogen, aryl which may be substituted with alkyl or cycloalkyl, alkyl or cycloalkyl, R of the >N-R and/or R of the >C(-R) ₂ may be bonded to at least one of the A ring, the B ring and the C ring by -O-, -S-, -C(-R) ₂ - or a single bond, R of the -C(-R) ₂ - is hydrogen, alkyl or cycloalkyl,
At least one hydrogen atom in the compound or structure represented by formula (1) may be replaced by deuterium, cyano or halogen;
In the case of a polymer, it is a dimer or trimer having two or three structures represented by general formula (1), and
At least one hydrogen atom in the compound or structure represented by formula (1) is substituted with a group represented by the above general formula (oR),
In the above formula (oR), R ¹ is an alkyl having 1 to 24 carbon atoms, R ²² to R ²⁵ are each independently hydrogen, an aryl having 6 to 30 carbon atoms, a heteroaryl having 2 to 30 carbon atoms, an alkyl having 1 to 24 carbon atoms, or a cycloalkyl having 3 to 24 carbon atoms, adjacent groups among R ²² to R ²⁵ may be bonded to each other to form an aryl ring having 9 to 16 carbon atoms or a heteroaryl ring having 6 to 15 carbon atoms together with a benzene ring, at least one hydrogen atom in the formed ring may be substituted with an aryl ring having 6 to 30 carbon atoms, a heteroaryl ring having 2 to 30 carbon atoms, an alkyl ring having 1 to 24 carbon atoms, or a cycloalkyl ring having 3 to 24 carbon atoms, and the group represented by the above formula (oR) is substituted with at least one hydrogen atom in the compound or structure represented by the above formula (1) at *,
Item 2. The electron transport material or electron injection material according to item 1.

（上記式（２）中、
Ｒ^１～Ｒ^１１は、それぞれ独立して、水素、アリール、ヘテロアリール、ジアリールアミノ、ジヘテロアリールアミノ、アリールヘテロアリールアミノ、ジアリールボリル（２つのアリールは単結合または連結基を介して結合していてもよい）、アルキル、シクロアルキル、アルコキシまたはアリールオキシであり、これらにおける少なくとも１つの水素は、アリール、ヘテロアリール、アルキルまたはシクロアルキルで置換されていてもよく、また、Ｒ^１～Ｒ^１１のうちの隣接する基同士が結合してａ環、ｂ環またはｃ環と共にアリール環またはヘテロアリール環を形成していてもよく、形成された環における少なくとも１つの水素は、アリール、ヘテロアリール、ジアリールアミノ、ジヘテロアリールアミノ、アリールヘテロアリールアミノ、ジアリールボリル（２つのアリールは単結合または連結基を介して結合していてもよい）、アルキル、シクロアルキル、アルコキシまたはアリールオキシで置換されていてもよく、これらにおける少なくとも１つの水素は、アリール、ヘテロアリール、アルキルまたはシクロアルキルで置換されていてもよく、
Ｙ^１は、Ｂ、Ｐ、Ｐ＝Ｏ、Ｐ＝Ｓ、Ａｌ、Ｇａ、Ａｓ、Ｓｉ－ＲまたはＧｅ－Ｒであり、前記Ｓｉ－ＲおよびＧｅ－ＲのＲは、炭素数６～１２のアリール、炭素数１～６のアルキルまたは炭素数３～１４のシクロアルキルであり、
Ｘ^１およびＸ^２は、それぞれ独立して、＞Ｏ、＞Ｎ－Ｒ、＞Ｃ（－Ｒ）_２、＞Ｓまたは＞Ｓｅであり、前記＞Ｎ－ＲのＲは、炭素数６～１２のアリール、炭素数２～１５のヘテロアリール、炭素数１～６のアルキルまたは炭素数３～１４のシクロアルキルであり、前記＞Ｃ（－Ｒ）_２のＲは、水素、炭素数６～１２のアリール、炭素数１～６のアルキルまたは炭素数３～１４のシクロアルキルであり、また、前記＞Ｎ－ＲのＲおよび／または前記＞Ｃ（－Ｒ）_２のＲは－Ｏ－、－Ｓ－、－Ｃ（－Ｒ）_２－または単結合により前記ａ環、ｂ環およびｃ環のうちの少なくとも１つと結合していてもよく、前記－Ｃ（－Ｒ）_２－のＲは炭素数１～６のアルキルまたは炭素数３～１４のシクロアルキルであり、
式（２）で表される化合物における少なくとも１つの水素は、重水素、シアノまたはハロゲンで置換されていてもよく、そして、
上記一般式（ｏＲ）で表される基は、＊において、前記ａ環、ｂ環、ｃ環、ならびにこれらの環と共に形成された前記アリール環およびヘテロアリール環のうちの少なくとも１つに結合しており、
上記式（ｏＲ）中、Ｒ^１は炭素数１～１２のアルキルであり、Ｒ^２２～Ｒ^２５は、それぞれ独立して、水素、炭素数６～１６のアリール、炭素数２～２０のヘテロアリール、炭素数１～１２のアルキルまたは炭素数３～１６のシクロアルキルであり、Ｒ^２２～Ｒ^２５のうちの隣接する基同士が結合してベンゼン環と共にナフタレン環、フェナントレン環、フルオレン環またはカルバゾール環を形成していてもよく、形成された環における少なくとも１つの水素は、炭素数６～１６のアリール、炭素数２～２０のヘテロアリール、炭素数１～１２のアルキルまたは炭素数３～１６のシクロアルキルで置換されていてもよい。） Item 3.
Item 2. The electron transport material or electron injection material according to item 1, wherein the polycyclic aromatic compound is represented by the following general formula (2):

(In the above formula (2),
R ¹ to R ¹¹ are each independently hydrogen, aryl, heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl (two aryls may be bonded via a single bond or a linking group), alkyl, cycloalkyl, alkoxy, or aryloxy, in which at least one hydrogen may be replaced by aryl, heteroaryl, alkyl, or cycloalkyl, or adjacent groups among R ¹ to R ¹¹ may be bonded to each other to form an aryl ring or heteroaryl ring together with ring a, ring b, or ring c, in which at least one hydrogen in the formed ring may be replaced by aryl, heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl (two aryls may be bonded via a single bond or a linking group), alkyl, cycloalkyl, alkoxy, or aryloxy, in which at least one hydrogen may be replaced by aryl, heteroaryl, alkyl, or cycloalkyl,
^Y1 is B, P, P=O, P=S, Al, Ga, As, Si-R or Ge-R, and R of the Si-R and Ge-R is an aryl having 6 to 12 carbon atoms, an alkyl having 1 to 6 carbon atoms or a cycloalkyl having 3 to 14 carbon atoms;
X ¹ and X ² are each independently >O, >N-R, >C(-R) ₂ , >S or >Se, R of the >N-R is an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, an alkyl having 1 to 6 carbon atoms or a cycloalkyl having 3 to 14 carbon atoms, R of the >C(-R) ₂ is hydrogen, an aryl having 6 to 12 carbon atoms, an alkyl having 1 to 6 carbon atoms or a cycloalkyl having 3 to 14 carbon atoms, R of the >N-R and/or R of the >C(-R) ₂ may be bonded to at least one of the ring a, ring b and ring c by -O-, -S-, -C(-R) ₂ - or a single bond, R of the -C(-R) ₂ - is an alkyl having 1 to 6 carbon atoms or a cycloalkyl having 3 to 14 carbon atoms,
At least one hydrogen atom in the compound represented by formula (2) may be replaced by deuterium, cyano or halogen, and
The group represented by the above general formula (oR) is bonded at * to at least one of the ring a, ring b, ring c, and the aryl ring and heteroaryl ring formed together with these rings,
In the above formula (oR), R ¹ is an alkyl having 1 to 12 carbon atoms, R ²² to R ²⁵ are each independently hydrogen, an aryl having 6 to 16 carbon atoms, a heteroaryl having 2 to 20 carbon atoms, an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms, and adjacent groups among R ²² to R ²⁵ may be bonded to each other to form a naphthalene ring, a phenanthrene ring, a fluorene ring, or a carbazole ring together with the benzene ring, and at least one hydrogen atom in the formed ring may be substituted with an aryl having 6 to 16 carbon atoms, a heteroaryl having 2 to 20 carbon atoms, an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms.

Item 4.
In the above formula (2),
R ¹ to R ¹¹ are each independently hydrogen, an aryl having 6 to 30 carbon atoms (the aryl may be substituted with a heteroaryl having 2 to 15 carbon atoms), a heteroaryl having 2 to 30 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 12 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 12 carbon atoms, and the two aryls may be bonded via a ^single bond or a linking group), an alkyl having 1 to 24 carbon atoms, or a cycloalkyl having 3 to 24 carbon atoms; adjacent groups among ¹¹ may be bonded to each other to form an aryl ring having 9 to 16 carbon atoms or a heteroaryl ring having 6 to 15 carbon atoms together with ring a, ring b or ring c, and at least one hydrogen in the formed ring may be substituted by an aryl having 6 to 30 carbon atoms (the aryl may be substituted with a heteroaryl having 2 to 15 carbon atoms), a heteroaryl having 2 to 30 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 12 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 12 carbon atoms, and two aryls may be bonded via a single bond or a linking group), an alkyl having 1 to 24 carbon atoms, or a cycloalkyl having 3 to 24 carbon atoms;
^Y1 is B, P, P=O, P=S or Si-R, wherein R of the Si-R is an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms;
^X1 and ^X2 are each independently >O, >N-R, >C(-R) ₂ or >S, R of the >N-R is an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms, and R of the >C(-R) ₂ is a hydrogen atom, an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms;
At least one hydrogen atom in the compound represented by formula (2) may be replaced by deuterium, cyano or halogen, and
The group represented by the above general formula (oR) is bonded at * to at least one of the ring a, ring b, ring c, and the aryl ring and heteroaryl ring formed together with these rings,
In the above formula (oR), R ¹ is an alkyl having 1 to 6 carbon atoms, R ²² to R ²⁵ are each independently a hydrogen atom, an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, an alkyl having 1 to 6 carbon atoms, or a cycloalkyl having 3 to 14 carbon atoms, adjacent groups among R ²² to R ²⁵ may be bonded to each other to form a naphthalene ring, a phenanthrene ring, a fluorene ring, or a carbazole ring together with a benzene ring, and at least one hydrogen atom in the formed ring may be substituted with an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, an alkyl having 1 to 6 carbon atoms, or a cycloalkyl having 3 to 14 carbon atoms;
Item 3. An electron transport material or an electron injection material according to item 3.

Item 5.
In the above formula (2),
R ¹ to R ¹¹ are each independently hydrogen, an aryl having 6 to 16 carbon atoms (the aryl may be substituted with a heteroaryl having 2 to 10 carbon atoms), a heteroaryl having 2 to 20 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 10 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 10 carbon atoms, and two aryls may be bonded via a single bond or a linking group), an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms;
^Y1 is B, P, P=O or P=S;
^X1 and ^X2 are each independently >O, >N-R, or >C(-R) ₂ , R of the >N-R is an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms, or a cycloalkyl having 5 to 10 carbon atoms, R of the >C(-R) ₂ is hydrogen, an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms, or a cycloalkyl having 5 to 10 carbon atoms, and
The group represented by the above general formula (oR) is bonded to at least one of the ring a, ring b and ring c at *,
In the above formula (oR), R ¹ is an alkyl group having 1 to 4 carbon atoms, and R ²² to R ²⁵ are each independently a hydrogen atom, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms.
Item 3. An electron transport material or an electron injection material according to item 3.

Item 6.
In the above formula (2),
R ¹ to R ¹¹ are each independently hydrogen, an aryl having 6 to 16 carbon atoms (the aryl may be substituted with a heteroaryl having 2 to 10 carbon atoms), a heteroaryl having 2 to 20 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 10 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 10 carbon atoms, and two aryls may be bonded via a single bond or a linking group), an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms;
^Y1 is B;
^X1 and ^X2 are each independently >O or >N-R, and R in the >N-R is an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms, or a cycloalkyl having 5 to 10 carbon atoms; and
The group represented by the above general formula (oR) is bonded to at least one of the ring a, ring b and ring c at *,
In the above formula (oR), R ¹ is an alkyl group having 1 to 4 carbon atoms, and R ²² to R ²⁵ are each independently a hydrogen atom, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms.
Item 3. An electron transport material or an electron injection material according to item 3.

Item 7.
In the above formula (2),
R ¹ to R ¹¹ are each independently hydrogen, an aryl having 6 to 16 carbon atoms (the aryl may be substituted with a heteroaryl having 2 to 10 carbon atoms), a heteroaryl having 2 to 20 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 10 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 10 carbon atoms, and two aryls may be bonded via a single bond or a linking group), an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms;
^Y1 is B or P=O;
^X1 and ^X2 are >O, and
The group represented by the above general formula (oR) is bonded to at least one of the ring a, ring b and ring c at *,
In the above formula (oR), R ¹ is an alkyl group having 1 to 4 carbon atoms, and R ²² to R ²⁵ are each independently a hydrogen atom, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms.
Item 3. An electron transport material or an electron injection material according to item 3.

Item 8.
In the above formula (2),
R ¹ to R ¹¹ are each independently hydrogen, an aryl having 6 to 16 carbon atoms (the aryl may be substituted with a heteroaryl having 2 to 10 carbon atoms), a heteroaryl having 2 to 20 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 10 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 10 carbon atoms, and two aryls may be bonded via a single bond or a linking group), an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms;
^Y1 is B;
^X1 and ^X2 are >O, and
The group represented by the above general formula (oR) is bonded to at least one of the ring a, ring b and ring c at *,
In the above formula (oR), R ¹ is an alkyl group having 1 to 4 carbon atoms, and R ²² to R ²⁵ are each independently a hydrogen atom, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms.
Item 3. An electron transport material or an electron injection material according to item 3.

Item 9.
In the above formula (2),
At least one of the ring a, ring b, and ring c is substituted with a diphenylamino group, a carbazolyl group, or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on at least one of the ring a, ring b, and ring c via a phenylene group; and
At least one of the ring a, ring b and ring c has a group represented by general formula (oR) bonded at *.
Item 9. An electron transport material or an electron injection material according to any one of Items 3 to 8.

Item 10.
In the above formula (2),
The ring a is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on the ring a via a phenylene group;
The ring b and the ring c each have a group represented by the general formula (oR) bonded thereto at *.
Item 9. An electron transport material or an electron injection material according to any one of Items 3 to 8.

Item 11.
11. The electron transport material or electron injection material according to any one of items 1 to 10, wherein in formula (1) or (2), the halogen is fluorine.

（各式中の「Ｍｅ」はメチルである。） Item 12.
Item 2. The electron transport material or electron injection material according to item 1, wherein the polycyclic aromatic compound is represented by the following structural formula:

(In each formula, "Me" is methyl.)

Item 13.
Item 13. An organic electroluminescence device comprising a pair of electrodes consisting of an anode and a cathode, a light-emitting layer disposed between the pair of electrodes, and an electron-transporting layer and/or an electron-injecting layer disposed between the cathode and the light-emitting layer and containing the electron-transporting material or the electron-injecting material according to any one of Items 1 to 12.

Item 14.
Item 14. The organic electroluminescence device according to item 13, wherein at least one of the electron transport layer and the electron injection layer contains at least one selected from the group consisting of borane derivatives, pyridine derivatives, fluoranthene derivatives, BO-based derivatives, anthracene derivatives, benzofluorene derivatives, phosphine oxide derivatives, pyrimidine derivatives, carbazole derivatives, triazine derivatives, benzimidazole derivatives, phenanthroline derivatives, and quinolinol-based metal complexes.

Item 15.
Item 15. The organic electroluminescence device according to item 14, wherein the electron transport layer and/or the electron injection layer further contains at least one selected from the group consisting of alkali metals, alkaline earth metals, rare earth metals, oxides of alkali metals, halides of alkali metals, oxides of alkaline earth metals, halides of alkaline earth metals, oxides of rare earth metals, halides of rare earth metals, organic complexes of alkali metals, organic complexes of alkaline earth metals, and organic complexes of rare earth metals.

Item 16.
Item 16. A display device or lighting device comprising the organic electroluminescent device according to any one of Items 13 to 15.

According to a preferred embodiment of the present invention, an excellent organic EL device can be provided by using a polycyclic aromatic compound having an alkyl group introduced at a specific position (specifically, the ortho position) as an electron transport material.

Specifically, the present inventors have found that a polycyclic aromatic compound (basic skeleton portion) in which aromatic rings are linked by hetero elements such as boron, phosphorus, oxygen, nitrogen, and sulfur has a large HOMO-LUMO gap (band gap Eg in a thin film) and a high triplet excitation energy (E _T ). This is believed to be due to the fact that a 6-membered ring containing a hetero element has low aromaticity, so that the decrease in the HOMO-LUMO gap accompanying the expansion of the conjugated system is suppressed, and that SOMO1 and SOMO2 in the triplet excited state (T1) are localized due to electronic perturbation of the hetero element. In addition, the polycyclic aromatic compound (basic skeleton portion) containing a hetero element according to the present invention has a small energy difference between the triplet excited state (T1) and the singlet excited state (S1), and exhibits thermally activated delayed fluorescence, and is therefore useful as a fluorescent material for an organic EL device. In addition, materials having high triplet excitation energy (E _T ) are also useful as electron transport layers or hole transport layers in phosphorescent organic EL devices or organic EL devices using thermally activated delayed fluorescence. Furthermore, these polycyclic aromatic compounds (basic skeleton portions) can arbitrarily change the energies of their HOMO and LUMO by introducing substituents, so that it is possible to optimize the ionization potential and electron affinity according to the surrounding materials.

In addition to these characteristics of the basic skeleton portion, the compound of the present invention has a group represented by the above general formula (oR) introduced into it, which results in an alkyl group being substituted at a specific position (specifically the ortho position), thereby increasing the glass transition temperature of the compound, thereby improving the heat resistance of the organic thin film and in particular improving the device life. Note that the present invention is not particularly limited to these principles.

1 is a schematic cross-sectional view showing an organic EL element according to an embodiment of the present invention.

1. Alkyl-substituted polycyclic aromatic compounds and multimers thereof The electron transport material or electron injection material according to the present invention contains a polycyclic aromatic compound represented by the following general formula (1) or a multimer of a polycyclic aromatic compound having a plurality of structures represented by the following general formula (1), and preferably contains a polycyclic aromatic compound represented by the following general formula (2) or a multimer of a polycyclic aromatic compound having a plurality of structures represented by the following general formula (2), and at least one hydrogen atom in these compounds or structures is substituted with a group represented by the following general formula (oR). In formula (1), "A" and "C" as well as "B" in the ring are each a symbol indicating a ring structure represented by a ring, and the other symbols are the same as defined above.

The A ring, B ring and C ring in the general formula (1) are each independently an aryl ring or a heteroaryl ring, and at least one hydrogen atom in these rings may be substituted with a substituent. The substituent is preferably a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino (an amino group having an aryl and a heteroaryl), a substituted or unsubstituted diarylboryl (two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted alkoxy, or a substituted or unsubstituted aryloxy. When these groups have a substituent, examples of the substituent include an aryl, a heteroaryl, an alkyl, or a cycloalkyl. In addition, the aryl ring or the heteroaryl ring preferably has a 5-membered or 6-membered ring that shares a bond with the central fused two-ring structure of the general formula (1) composed of Y ¹ , X ¹ and X ² .

Here, the term "fused bicyclic structure" refers to a structure in which two saturated hydrocarbon rings, which are constituted by Y ¹ , X ¹ and X ² , are fused together, as shown in the center of the general formula (1). The term "six-membered ring sharing a bond with the fused bicyclic structure" refers to the a ring (benzene ring (six-membered ring)) fused to the fused bicyclic structure, as shown in the general formula (2) above. The term "aryl ring or heteroaryl ring (A ring) has this six-membered ring" refers to the A ring being formed by this six-membered ring alone, or the A ring being formed by further condensing other rings to this six-membered ring so as to include this six-membered ring. In other words, the term "aryl ring or heteroaryl ring (A ring) having a six-membered ring" refers to the six-membered ring constituting all or part of the A ring being fused to the fused bicyclic structure. The same explanation applies to "B ring (b ring)", "C ring (c ring)" and "five-membered ring".

Ring A (or ring B, ring C) in general formula (1) corresponds to ring a and its substituents R ¹ to R ³ (or ring b and its substituents R ⁸ to R ¹¹ , ring c and its substituents R ⁴ to R ⁷ ) in general formula (2). That is, general formula (2) corresponds to a structure in which "rings A to C having 6-membered rings" are selected as rings A to C in general formula (1). In that sense, each ring in general formula (2) is represented by lower case letters a to c.

In general formula (2), adjacent groups among the substituents R ¹ to R ¹¹ of the ring a, ring b, and ring c may be bonded together to form an aryl ring or a heteroaryl ring together with the ring a, ring b, or ring c, and at least one hydrogen atom in the formed ring may be substituted with an aryl, heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl (two aryls may be bonded via a single bond or a linking group), alkyl, cycloalkyl, alkoxy, or aryloxy, and at least one hydrogen atom in these may be substituted with an aryl, heteroaryl, alkyl, or cycloalkyl. Therefore, the ring structure constituting the polycyclic aromatic compound represented by general formula (2) changes depending on the mutual bonding form of the substituents in the ring a, ring b, and ring c, as shown in the following formulas (2-1) and (2-2). The ring A', ring B', and ring C' in each formula correspond to the ring A, ring B, and ring C in general formula (1), respectively. In addition, the definitions of R ¹ to R ¹¹ , a, b, c, Y ¹ , X ¹ and X ² in each formula are the same as those in formula (2).

In the above formula (2-1) and formula (2-2), the A' ring, B' ring, and C' ring are aryl or heteroaryl rings formed with the a ring, b ring, and c ring by bonding adjacent groups among the substituents R ¹ to R ¹¹ , respectively (they may also be considered as condensed rings formed by condensing other ring structures to the a ring, b ring, or c ring). Although not shown in the formula, there are also compounds in which the a ring, b ring, and c ring are all changed to the A' ring, B' ring, and C' ring. In addition, as can be seen from the above formula (2-1) and formula (2-2), for example, R ⁸ of the b ring and R ⁷ of the c ring, R ¹¹ of the b ring and R ¹ of the a ring, R ⁴ of the c ring and R ³ of the a ring, etc. do not fall under the category of "adjacent groups", and they are not bonded to each other. In other words, "adjacent groups" means adjacent groups on the same ring.

The compounds represented by the above formula (2-1) or formula (2-2) are compounds having ring A' (or ring B' or ring C') formed by condensing a benzene ring, which is ring a (or ring b or ring c), with a benzene ring, an indole ring, a pyrrole ring, a benzofuran ring or a benzothiophene ring, and the condensed ring A' (or condensed ring B' or condensed ring C') formed is a naphthalene ring, a carbazole ring, an indole ring, a dibenzofuran ring or a dibenzothiophene ring, respectively.

Y ¹ in the general formula (1) is B, P, P=O, P=S, Al, Ga, As, Si-R or Ge-R, and R in the Si-R and Ge-R is aryl, alkyl or cycloalkyl. In the case of P=O, P=S, Si-R or Ge-R, the atom bonded to the A ring, B ring or C ring is P, Si or Ge. Y ¹ is preferably B, P, P=O, P=S or Si-R, more preferably B or P=O, and particularly preferably B. This explanation is the same for Y ¹ in the general formula (2).

In general formula (1), X ¹ and X ² are each independently >O, >N-R, >C(-R) ₂ , >S or >Se, R of the >N-R is an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted alkyl or an optionally substituted cycloalkyl, R of the >C(-R) ₂ is hydrogen, an optionally substituted aryl, an alkyl or a cycloalkyl, R of the >N-R and/or R of the >C(-R) ₂ may be bonded to at least one of the A ring, the B ring and the C ring via a linking group or a single bond, and the linking group is preferably -O-, -S- or -C(-R) ₂ -. Note that R of the "-C(-R) ₂ -" is hydrogen, an alkyl or a cycloalkyl. ^X1 and ^X2 are each independently preferably >O, >N-R or >C(-R) ₂ , more preferably >O or >N-R, and particularly preferably >O. This explanation also applies to ^X1 and ^X2 in general formula (2).

Here, the provision in general formula (1) that "R of the >N-R and/or R of the >C(-R) ₂ is bonded to at least one of the A ring, the B ring and the C ring via a linking group or a single bond" corresponds to the provision in general formula (2) that "R of the >N-R and/or R of the >C(-R) ₂ is bonded to at least one of the a ring, the b ring and the c ring via -O-, -S-, -C(-R) ₂ - or a single bond."

This definition can be expressed by a compound having a ring structure in which ^X1 and ^X2 are incorporated into fused ring B' and fused ring C', as represented by the following formula (2-3-1). That is, for example, it is a compound having ring B' (or ring C') formed by condensing another ring so as to incorporate ^X1 (or ^X2 ) into the benzene ring, which is ring b (or ring c) in general formula (2). The fused ring B' (or fused ring C') thus formed is, for example, a phenoxazine ring, a phenothiazine ring, or an acridine ring.

The above definition can also be expressed by a compound having a ring structure in which ^X1 and/or ^X2 are incorporated into a fused ring A', as represented by the following formula (2-3-2) or formula (2-3-3). That is, for example, it is a compound having a ring A' formed by condensing another ring to the benzene ring, which is the ring a in general formula (2), so as to incorporate ^X1 (and/or ^X2 ). The fused ring A' thus formed is, for example, a phenoxazine ring, a phenothiazine ring, or an acridine ring.

上記各式中のＲ^１～Ｒ^１１、ａ、ｂ、ｃ、Ｙ^１、Ｘ^１およびＸ^２の定義は一般式（２）における定義と同じである。

In the above formulas, the definitions of R ¹ to R ¹¹ , a, b, c, Y ¹ , X ¹ and X ² are the same as those in general formula (2).

Examples of the "aryl ring" which is ring A, ring B and ring C in general formula (1) include aryl rings having 6 to 30 carbon atoms, preferably aryl rings having 6 to 16 carbon atoms, more preferably aryl rings having 6 to 12 carbon atoms, and particularly preferably aryl rings having 6 to 10 carbon atoms. This "aryl ring" corresponds to "an aryl ring formed together with ring a, ring b or ring c by bonding adjacent groups among R ¹ to R ¹¹ " defined in general formula (2), and since ring a (or ring b or ring c) is already composed of a benzene ring having 6 carbon atoms, the lower limit of the carbon number is 9, which is the total carbon number of the fused rings fused with a 5-membered ring.

Specific examples of "aryl rings" include a monocyclic benzene ring, a bicyclic ...

Examples of the "heteroaryl ring" which is the ring A, ring B and ring C in general formula (1) include heteroaryl rings having 2 to 30 carbon atoms, preferably heteroaryl rings having 2 to 25 carbon atoms, more preferably heteroaryl rings having 2 to 20 carbon atoms, even more preferably heteroaryl rings having 2 to 15 carbon atoms, and particularly preferably heteroaryl rings having 2 to 10 carbon atoms. Examples of the "heteroaryl ring" include heterocycles containing, in addition to carbon, 1 to 5 heteroatoms selected from oxygen, sulfur and nitrogen as ring-constituting atoms. This "heteroaryl ring" corresponds to the "heteroaryl ring formed together with ring a, ring b or ring c by bonding adjacent groups among R ¹ to R ¹¹ " defined in general formula (2), and since ring a (or ring b or ring c) is already composed of a benzene ring having 6 carbon atoms, the total carbon number of the fused rings to which the 5-membered ring is fused is 6, which is the lower limit of the carbon number.

Specific examples of the "heteroaryl ring" include a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, an oxadiazole ring, a thiadiazole ring, a triazole ring, a tetrazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, an indole ring, an isoindole ring, a 1H-indazole ring, a benzimidazole ring, a benzoxazole ring, a benzothiazole ring, and a 1H-benzotriazo Examples of such rings include an aryl ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinazoline ring, a quinoxaline ring, a phthalazine ring, a naphthyridine ring, a purine ring, a pteridine ring, a carbazole ring, an acridine ring, a phenoxathiin ring, a phenoxazine ring, a phenothiazine ring, a phenazine ring, a phenazasiline ring, an indolizine ring, a furan ring, a benzofuran ring, an isobenzofuran ring, a dibenzofuran ring, a thiophene ring, a benzothiophene ring, a dibenzothiophene ring, a furazan ring, and a thianthrene ring.

At least one hydrogen atom in the above "aryl ring" or "heteroaryl ring" may be substituted with a first substituent, which is a substituted or unsubstituted "aryl", a substituted or unsubstituted "heteroaryl", a substituted or unsubstituted "diarylamino", a substituted or unsubstituted "diheteroarylamino", a substituted or unsubstituted "arylheteroarylamino", a substituted or unsubstituted "diarylboryl (the two aryls may be bonded via a single bond or a linking group)", a substituted or unsubstituted "alkyl", a substituted or unsubstituted "cycloalkyl", a substituted or unsubstituted "alkoxy", or a substituted or unsubstituted "aryloxy". Examples of the first substituents, such as "aryl" or "heteroaryl", the aryl of "diarylamino", the heteroaryl of "diheteroarylamino", the aryl and heteroaryl of "arylheteroarylamino", the aryl of "diarylboryl", and the aryl of "aryloxy", include the monovalent groups of the above-mentioned "aryl ring" or "heteroaryl ring".

The "alkyl" as the first substituent may be either linear or branched, for example, linear alkyl having 1 to 24 carbon atoms or branched alkyl having 3 to 24 carbon atoms. An alkyl having 1 to 18 carbon atoms (branched alkyl having 3 to 18 carbon atoms) is preferred, an alkyl having 1 to 12 carbon atoms (branched alkyl having 3 to 12 carbon atoms) is more preferred, an alkyl having 1 to 6 carbon atoms (branched alkyl having 3 to 6 carbon atoms) is even more preferred, and an alkyl having 1 to 4 carbon atoms (branched alkyl having 3 to 4 carbon atoms) is particularly preferred. As the alkyl having 1 to 4 carbon atoms, a methyl group and a t-butyl group are more preferred, with a t-butyl group being even more preferred.

Specific alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, n-octyl, t-octyl, 1-methylheptyl, 2 -ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 2,6-dimethyl-4-heptyl, 3,5,5-trimethylhexyl, n-decyl, n-undecyl, 1-methyldecyl, n-dodecyl, n-tridecyl, 1-hexylheptyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, and n-eicosyl.

Examples of "cycloalkyl" as the first substituent include cycloalkyl having 3 to 24 carbon atoms, cycloalkyl having 3 to 20 carbon atoms, cycloalkyl having 3 to 16 carbon atoms, cycloalkyl having 3 to 14 carbon atoms, cycloalkyl having 5 to 10 carbon atoms, cycloalkyl having 5 to 8 carbon atoms, cycloalkyl having 5 to 6 carbon atoms, and cycloalkyl having 5 carbon atoms.

Specific examples of cycloalkyl include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, and alkyl (especially methyl) substituted derivatives of these having 1 to 4 carbon atoms, as well as norbornenyl, bicyclo[1.0.1]butyl, bicyclo[1.1.1]pentyl, bicyclo[2.0.1]pentyl, bicyclo[1.2.1]hexyl, bicyclo[3.0.1]hexyl, bicyclo[2.1.2]heptyl, bicyclo[2.2.2]octyl, adamantyl, diamantyl, decahydronaphthalenyl, and decahydroazulenyl.

Examples of "alkoxy" as the first substituent include linear alkoxy having 1 to 24 carbon atoms or branched alkoxy having 3 to 24 carbon atoms. Alkoxy having 1 to 18 carbon atoms (branched alkoxy having 3 to 18 carbon atoms) is preferred, alkoxy having 1 to 12 carbon atoms (branched alkoxy having 3 to 12 carbon atoms) is more preferred, alkoxy having 1 to 6 carbon atoms (branched alkoxy having 3 to 6 carbon atoms) is even more preferred, and alkoxy having 1 to 4 carbon atoms (branched alkoxy having 3 to 4 carbon atoms) is particularly preferred.

Specific examples of alkoxy include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, s-butoxy, t-butoxy, pentyloxy, hexyloxy, heptyloxy, and octyloxy.

As for the "aryl" in the "diarylboryl" as the first substituent, the above description of the aryl can be cited. Furthermore, the two aryls may be bonded via a single bond or a linking group (for example, >C(-R) ₂ , >O, >S, or >N-R). Here, R in >C(-R) ₂ and >N-R is aryl, heteroaryl, diarylamino, alkyl, cycloalkyl, alkoxy, or aryloxy (the above, the first substituent), and the first substituent may be further substituted with aryl, heteroaryl, alkyl, or cycloalkyl (the above, the second substituent), and as specific examples of these groups, the above description of the aryl, heteroaryl, diarylamino, alkyl, cycloalkyl, alkoxy, or aryloxy as the first substituent can be cited.

Specifically, the emission wavelength can be adjusted by the steric hindrance, electron donating property and electron withdrawing property of the structure of the first substituent, and is preferably a group represented by any one of the following structural formulas (S-1) to (S-94), more preferably a group represented by any one of formulas (S-1), (S-2), (S-5), (S-9) to (S-19), (S-24) to (S-50) and (S-51) to (S-94), and even more preferably a group represented by formula (S-1) , a group represented by any one of formulas (S-2), (S-5), (S-9), (S-10), (S-15), (S-16), (S-24), (S-30), (S-46), (S-48), (S-50), (S-51), (S-56) to (S-58), (S-70), (S-71), (S-73), (S-74), (S-76), (S-79), (S-80), (S-83), and (S-84).

In the structural formula below, "Me" represents methyl and "tBu" represents t-butyl.

As explained above, the first substituents, substituted or unsubstituted "aryl", substituted or unsubstituted "heteroaryl", substituted or unsubstituted "diarylamino", substituted or unsubstituted "diheteroarylamino", substituted or unsubstituted "arylheteroarylamino", substituted or unsubstituted "diarylboryl (two aryls may be bonded via a single bond or a linking group)", substituted or unsubstituted "alkyl", substituted or unsubstituted "cycloalkyl", substituted or unsubstituted "alkoxy", or substituted or unsubstituted "aryloxy", may have at least one hydrogen atom substituted with a second substituent. Examples of the second substituent include aryl, heteroaryl, alkyl, or cycloalkyl, and the specific groups thereof can be referred to the above-mentioned monovalent groups of the "aryl ring" or "heteroaryl ring", and the explanation of the "alkyl" or "cycloalkyl" as the first substituent. In addition, the aryl and heteroaryl as the first and second substituents also include groups in which at least one hydrogen atom is substituted with an aryl such as phenyl (specific examples are the groups described above), an alkyl such as methyl (specific examples are the groups described above), or a cycloalkyl such as cyclohexyl (specific examples are the groups described above). As an example, when the first and second substituents are carbazolyl groups, the heteroaryl as the first and second substituents also includes a carbazolyl group in which at least one hydrogen atom at the 9-position is substituted with an aryl such as phenyl, an alkyl such as methyl, or a cycloalkyl such as cyclohexyl. In addition, when the first and second substituents are benzimidazole groups, the heteroaryl as the first and second substituents also includes a benzimidazole group in which at least one hydrogen atom in this group is substituted with an aryl such as phenyl, an alkyl such as methyl, or a cycloalkyl such as cyclohexyl.

In the general formula (2), the aryl, heteroaryl, aryl of diarylamino, heteroaryl of diheteroarylamino, aryl and heteroaryl of arylheteroarylamino, aryl of diarylboryl, or aryl of aryloxy in R ¹ to R ¹¹ include the monovalent group of "aryl ring" or "heteroaryl ring" explained in the general formula (1). In addition, for the alkyl, cycloalkyl, or alkoxy in R ¹ to R ¹¹ , the explanation of "alkyl", "cycloalkyl" or "alkoxy" as the first substituent in the explanation of the general formula (1) above can be referred to. Furthermore, the same applies to the aryl, heteroaryl, alkyl, or cycloalkyl as the substituent on these groups. In addition, in the case where adjacent groups among R ¹ to R ¹¹ are bonded to each other to form an aryl ring or heteroaryl ring together with the a ring, the b ring, or the c ring, the same applies to the heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl, alkyl, cycloalkyl, alkoxy, or aryloxy as the substituent on these rings, and the further aryl, heteroaryl, alkyl, or cycloalkyl as the substituent.

R of Si-R and Ge-R in ^Y1 in general formula (1) is aryl, alkyl or cycloalkyl, and examples of this aryl, alkyl or cycloalkyl include the groups described above. In particular, aryl having 6 to 10 carbon atoms (e.g., phenyl, naphthyl, etc.), alkyl having 1 to 4 carbon atoms (e.g., methyl, ethyl, t-butyl, etc., especially t-butyl), or cycloalkyl having 5 to 10 carbon atoms (preferably cyclohexyl or adamantyl) are preferred. This explanation is also applicable to ^Y1 in general formula (2).

R of >N-R in ^X1 and ^X2 in general formula (1) is an aryl, heteroaryl, alkyl or cycloalkyl which may be substituted with the second substituent described above, and at least one hydrogen in the aryl or heteroaryl may be substituted with, for example, an alkyl or cycloalkyl. Examples of the aryl, heteroaryl, alkyl and cycloalkyl include the groups described above. In particular, an aryl having 6 to 10 carbon atoms (e.g., phenyl, naphthyl, etc.), a heteroaryl having 2 to 15 carbon atoms (e.g., carbazolyl, etc.), an alkyl having 1 to 4 carbon atoms (e.g., methyl, ethyl, t-butyl, etc., especially t-butyl), or a cycloalkyl having 5 to 10 carbon atoms (preferably cyclohexyl or adamantyl) is preferred. This explanation is the same for ^X1 and ^X2 in general formula (2).

R in >C(-R) ₂ in ^X1 and ^X2 in general formula (1) is hydrogen, an aryl which may be substituted with the second substituent described above, an alkyl or a cycloalkyl, and at least one hydrogen in the aryl may be substituted with, for example, an alkyl or a cycloalkyl. Examples of the aryl, alkyl or cycloalkyl include the groups described above. In particular, an aryl having 6 to 10 carbon atoms (e.g., phenyl, naphthyl, etc.), an alkyl having 1 to 4 carbon atoms (e.g., methyl, ethyl, t-butyl, etc., especially t-butyl), or a cycloalkyl having 5 to 10 carbon atoms (preferably cyclohexyl or adamantyl) is preferred. This explanation is the same for ^X1 and ^X2 in general formula (2).

In the linking group "-C(-R) ₂ -" in general formula (1), R is hydrogen, alkyl, or cycloalkyl, and examples of this alkyl or cycloalkyl include the groups described above. In particular, alkyl having 1 to 4 carbon atoms (e.g., methyl, ethyl, t-butyl, etc., especially t-butyl) or cycloalkyl having 5 to 10 carbon atoms (preferably cyclohexyl or adamantyl) is preferred. This explanation also applies to the linking group "-C(-R) ₂ -" in general formula (2).

The present invention also relates to a multimer of a polycyclic aromatic compound having a plurality of unit structures represented by general formula (1), preferably a multimer of a polycyclic aromatic compound having a plurality of unit structures represented by general formula (2). The multimer is preferably a dimer to a hexamer, more preferably a dimer to a trimer, and particularly preferably a dimer. The multimer may have a form having a plurality of the above unit structures in one compound. For example, in addition to a form in which a plurality of the above unit structures are bonded together via a linking group such as a single bond, an alkylene group having 1 to 3 carbon atoms, a phenylene group, or a naphthylene group (linked multimer), the multimer may have a form in which any ring (ring A, ring B or ring C, ring a, ring b or ring c) contained in the above unit structure is bonded together so as to be shared by the plurality of unit structures (ring-shared multimer), or may have a form in which any ring (ring A, ring B or ring C, ring a, ring b or ring c) contained in the above unit structure is bonded together so as to be condensed (ring-condensed multimer). However, ring-shared multimers and ring-condensed multimers are preferred, and ring-shared multimers are more preferred.

Examples of such multimers include multimer compounds represented by the following formulas (2-4), (2-4-1), (2-4-2), (2-5-1) to (2-5-4), or (2-6). The multimer compound represented by the following formula (2-4) is a multimer compound (ring-sharing multimer) having a plurality of unit structures represented by general formula (2) in one compound, with the benzene ring being the a-ring shared, when described in terms of general formula (2). The multimer compound represented by the following formula (2-4-1) is a multimer compound (ring-sharing multimer) having two unit structures represented by general formula (2) in one compound, with the benzene ring being the a-ring shared, when described in terms of general formula (2). Moreover, the multimeric compound represented by the following formula (2-4-2) is a multimeric compound (ring-sharing type multimer) having three unit structures represented by the general formula (2) in one compound, so as to share a benzene ring which is an a-ring, when described in the general formula (2). Moreover, the multimeric compound represented by the following formulas (2-5-1) to (2-5-4) is a multimeric compound (ring-sharing type multimer) having a plurality of unit structures represented by the general formula (2) in one compound, so as to share a benzene ring which is a b-ring (or a-ring) in one compound, when described in the general formula (2). Moreover, the multimeric compound represented by the following formula (2-6) is a multimeric compound (ring-condensed type multimer) having a plurality of unit structures represented by the general formula (2) in one compound, so as to condense a benzene ring which is a b-ring (or a-ring, c-ring) in one unit structure with a benzene ring which is a b-ring (or a-ring, c-ring) in one unit structure.

The multimeric compound may be a multimer in which a multimerization form represented by formula (2-4), formula (2-4-1) or formula (2-4-2) is combined with a multimerization form represented by any one of formulas (2-5-1) to (2-5-4) or formula (2-6); a multimer in which a multimerization form represented by any one of formulas (2-5-1) to (2-5-4) is combined with a multimerization form represented by formula (2-6); or a multimer in which a multimerization form represented by formula (2-4), formula (2-4-1) or formula (2-4-2) is combined with a multimerization form represented by any one of formulas (2-5-1) to (2-5-4) and a multimerization form represented by formula (2-6).

In addition, all or a part of hydrogen in the chemical structure of the polycyclic aromatic compound and its multimer represented by general formula (1) or (2) may be deuterium, cyano, or halogen. For example, in formula (1), hydrogen in the rings A, B, and C (rings A to C are aryl or heteroaryl rings), the substituents on rings A to C, R (= alkyl, cycloalkyl, aryl) when Y ¹ is Si-R or Ge-R, R (= alkyl, cycloalkyl, aryl) when X ¹ and X ² are >N-R or >C(-R) ₂ , and the group of general formula (oR) described below may be replaced with deuterium, cyano, or halogen, and among these, embodiments in which all or a part of hydrogen in the aryl or heteroaryl is replaced with deuterium, cyano, or halogen are exemplified. The halogen is fluorine, chlorine, bromine, or iodine, preferably fluorine, chlorine, or bromine, and more preferably fluorine or chlorine.

In addition, at least one hydrogen atom in the chemical structure of the polycyclic aromatic compound represented by general formula (1) or (2) and its multimer is substituted with a group represented by general formula (oR) below, and all or a part of the hydrogen atoms may be a group represented by formula (oR) below.

In the above formula (oR), R ²¹ is alkyl, R ²² to R ²⁵ are each independently hydrogen, aryl, heteroaryl, alkyl or cycloalkyl, adjacent groups among R ²² to R ²⁵ may be bonded to each other to form an aryl ring or heteroaryl ring together with a benzene ring, at least one hydrogen atom in the formed ring may be replaced by an aryl, heteroaryl, alkyl or cycloalkyl, and the group represented by the above formula (oR) replaces at least one hydrogen atom in the compound or structure represented by the above formula (1) at *.

The "alkyl" of R ²¹ may be either linear or branched, and examples thereof include linear alkyl having 1 to 24 carbon atoms or branched alkyl having 3 to 24 carbon atoms. An alkyl having 1 to 18 carbon atoms (branched alkyl having 3 to 18 carbon atoms) is preferred, an alkyl having 1 to 12 carbon atoms (branched alkyl having 3 to 12 carbon atoms) is more preferred, an alkyl having 1 to 6 carbon atoms (branched alkyl having 3 to 6 carbon atoms) is even more preferred, and an alkyl having 1 to 4 carbon atoms (branched alkyl having 3 to 4 carbon atoms) is particularly preferred. As the alkyl having 1 to 4 carbon atoms, a methyl group and a t-butyl group are more preferred, and a methyl group is even more preferred.

Specific alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, n-octyl, t-octyl, 1-methylheptyl, 2 -ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 2,6-dimethyl-4-heptyl, 3,5,5-trimethylhexyl, n-decyl, n-undecyl, 1-methyldecyl, n-dodecyl, n-tridecyl, 1-hexylheptyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, and n-eicosyl.

For the "aryl", "heteroaryl", "alkyl" or "cycloalkyl" in R ²² to R ²⁵ , the explanation for the first substituent above can be cited.

Adjacent groups among R ²² to R ²⁵ may be bonded to each other to form an aryl ring or a heteroaryl ring together with the benzene ring, and at least one hydrogen in the formed ring may be substituted with an aryl, heteroaryl, alkyl, or cycloalkyl, and for the explanation of these, the explanation of the case where adjacent groups among R ¹ to R ¹¹ are bonded to each other to form an aryl ring or a heteroaryl ring together with the ring a, ring b, or ring c in the above general formula (2) can be cited. Specific examples of the aryl ring or heteroaryl ring formed together with the benzene ring include a naphthalene ring, a phenanthrene ring, a fluorene ring, and a carbazole ring.

The group represented by formula (oR) may be substituted for at least one hydrogen atom in the compound or structure represented by formula (1), but is preferably directly bonded to at least one of ring A, ring B, and ring C of general formula (1) (in general formula (2), at least one of ring a, ring b, ring c, and aryl and heteroaryl rings formed together with ring a, ring b, or ring c by bonding adjacent groups among R ¹ to R ¹¹ ). More preferably, it is directly bonded to ring B and/or ring C of general formula (1) (in general formula (2), ring b and/or ring c, or aryl and/or heteroaryl rings formed together with ring b or ring c by bonding adjacent groups among R ⁴ to R ¹¹ ). More preferably, it is directly bonded to both of ring B and ring C in general formula (1) (in general formula (2), to both ring b and ring c, or to both an aryl ring or heteroaryl ring formed together with ring b by bonding adjacent groups among R ⁸ to R ¹¹ , and to both an aryl ring or heteroaryl ring formed together with ring c by bonding adjacent groups among R ⁴ to R ⁷ ).

Furthermore, the polycyclic aromatic compounds and their multimers represented by general formula (1) or (2) are preferably substituted with a diarylamino group (particularly a diphenylamino group), a carbazolyl group, or a benzocarbazolyl group, and these groups may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms. These groups may also be substituted on the polycyclic aromatic compounds and their multimers via a phenylene group.

These groups are preferably bonded directly or via a phenylene group to at least one of ring A, ring ^B , and ring C in general formula (1) (at least one of ring a, ring b, ring c, and an aryl ring and heteroaryl ring formed together with ring a, ring b, or ring c by bonding adjacent groups among R 1 to R ¹¹ in general formula (2)). More preferably, they are bonded directly or via a phenylene group to ring A in general formula (1) (ring a, or an aryl ring or heteroaryl ring formed together with ring a by bonding adjacent groups among R ¹ to R ³ in general formula (2)).

Further specific examples of the alkyl-substituted polycyclic aromatic compounds of the present invention include compounds represented by the following structural formula: In the structural formula, "Me" represents a methyl group, "Et" represents an ethyl group, "iPr" represents a propyl group, "Hep" represents a heptyl group, "tBu" represents a t-butyl group, and "CN" represents a cyano group.

2. Method for producing alkyl-substituted polycyclic aromatic compounds and their multimers Polycyclic aromatic compounds and their multimers represented by general formula (1) or (2) can be synthesized by applying the method disclosed in, for example, International Publication No. 2015/102118. Basically, an intermediate is produced by first bonding the A ring (a ring), the B ring (b ring), and the C ring (c ring) with a bonding group (a group containing ^X1 or ^X2 ) (first reaction), and then the A ring (a ring), the B ring (b ring), and the C ring (c ring) with a bonding group (a group containing ^Y1 ) to produce the final product (second reaction). In addition, by using a raw material substituted with a group represented by formula (oR) somewhere in these reaction steps or adding a step of introducing a group represented by formula (oR), the compound of the present invention in which the desired position is alkyl-substituted can be produced.

In the first reaction, for example, if it is an etherification reaction, a common reaction such as a nucleophilic substitution reaction or the Ullmann reaction can be used, and if it is an amination reaction, a common reaction such as the Buchwald-Hartwig reaction can be used. In addition, in the second reaction, a tandem hetero Friedel-Crafts reaction (sequential aromatic electrophilic substitution reaction, the same applies below) can be used.

The second reaction is a reaction to introduce Y ¹ that bonds the A ring (a ring), the B ring (b ring) and the C ring (c ring), as shown in the following schemes (1) and (2). An example in which Y ¹ is a boron atom and X ¹ and X ² are oxygen atoms is shown below. First, the hydrogen atom between X ¹ and X ² is orthometalated with n-butyllithium, sec-butyllithium, t-butyllithium or the like. Next, boron trichloride, boron tribromide or the like is added to perform lithium-boron metal exchange, and then a tandem boron-Friedel-Crafts reaction is carried out by adding a Bronsted base such as N,N-diisopropylethylamine to obtain the target product. In the second reaction, a Lewis acid such as aluminum trichloride may be added to promote the reaction. The symbols in the structural formulae in the following schemes (1) and (2) and the subsequent schemes (3) to (5) are defined as above.

The above schemes (1) and (2) mainly show the method for producing the polycyclic aromatic compounds represented by the general formulas (1) and (2), but their multimers can be produced by using intermediates having multiple A rings (a rings), B rings (b rings), and C rings (c rings). Details are explained in the following schemes (3) to (5). In this case, the target product can be obtained by doubling or tripling the amount of the reagent such as butyllithium used.

In the above scheme, lithium was introduced at the desired position by orthometalation, but lithium can also be introduced at the desired position by introducing a halogen such as a bromine atom at the desired position and then performing halogen-metal exchange.

In addition, polycyclic aromatic compounds in which a group represented by general formula (oR) is bonded to ring a, ring b and/or ring c (particularly ring a) in general formula (2), and further in which ring a, ring b and/or ring c (particularly ring b and/or ring c) are substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group (which may be substituted on ring a, ring b and/or ring c via a phenylene group), which may be substituted with an alkyl group having 1 to 4 carbon atoms, can also be produced in the same manner according to the above scheme.

For example, in the case of a polycyclic aromatic compound (M-5) having a group represented by general formula (oR) and a diphenylamino group, as shown in the following scheme (6), an intermediate (M-2) substituted with a diphenylamino group and an intermediate (M-3) substituted with a group represented by formula (oR) are synthesized, and these are combined to synthesize intermediate (M-4), which is then cyclized to synthesize polycyclic aromatic compound (M-5). In scheme (6), Hal represents a halogen, X represents a halogen or hydrogen, and the other symbols are defined the same as those in general formula (2).

The intermediate before cyclization in scheme (6) can also be synthesized by the method shown in scheme (1) etc. In other words, by appropriately combining the Buchwald-Hartwig reaction, Suzuki coupling reaction, or etherification reaction by nucleophilic substitution reaction, Ullmann reaction etc., an intermediate having the desired substituent can be synthesized. In these reactions, commercially available products can also be used as the precursor raw materials.

3. Organic Electroluminescence Device The organic EL device according to the present embodiment will now be described in detail with reference to the drawings. Fig. 1 is a schematic cross-sectional view showing the organic EL device according to the present embodiment.

<Structure of Organic Electroluminescent Device>
The organic EL element 100 shown in FIG. 1 has a substrate 101, an anode 102 provided on the substrate 101, a hole injection layer 103 provided on the anode 102, a hole transport layer 104 provided on the hole injection layer 103, a light emitting layer 105 provided on the hole transport layer 104, an electron transport layer 106 provided on the light emitting layer 105, an electron injection layer 107 provided on the electron transport layer 106, and a cathode 108 provided on the electron injection layer 107.

In addition, the organic EL element 100 may be fabricated in the reverse order, for example, to have a substrate 101, a cathode 108 provided on the substrate 101, an electron injection layer 107 provided on the cathode 108, an electron transport layer 106 provided on the electron injection layer 107, an emitting layer 105 provided on the electron transport layer 106, a hole transport layer 104 provided on the emitting layer 105, a hole injection layer 103 provided on the hole transport layer 104, and an anode 102 provided on the hole injection layer 103.

Not all of the above layers are essential, and the minimum structural unit is the anode 102, the light-emitting layer 105, and the cathode 108. The hole injection layer 103, the hole transport layer 104, the electron transport layer 106, and the electron injection layer 107 are layers that are optionally provided. Each of the above layers may be a single layer or multiple layers.

In addition to the above-mentioned "substrate/anode/hole injection layer/hole transport layer/light-emitting layer/electron transport layer/electron injection layer/cathode" configuration, the layers constituting the organic EL element may be "substrate/anode/hole transport layer/light-emitting layer/electron transport layer/electron injection layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron transport layer/electron injection layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron transport layer/electron injection layer/cathode", "substrate/anode/hole injection layer/hole transport layer/light-emitting ... transport", The configuration may be "substrate/anode/light-emitting layer/electron transport layer/electron injection layer/cathode", "substrate/anode/hole transport layer/light-emitting layer/electron injection layer/cathode", "substrate/anode/hole transport layer/light-emitting layer/electron transport layer/cathode", "substrate/anode/hole transport layer/light-emitting layer/electron transport layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron injection layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron transport layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron transport layer/cathode", "substrate/anode/light-emitting layer/electron transport layer/cathode", or "substrate/anode/light-emitting layer/electron injection layer/cathode".

<Substrate in Organic Electroluminescent Device>
The substrate 101 is a support for the organic EL element 100, and is usually made of quartz, glass, metal, plastic, or the like. The substrate 101 is formed into a plate, film, or sheet shape depending on the purpose, and for example, a glass plate, a metal plate, a metal foil, a plastic film, a plastic sheet, or the like is used. Among them, a glass plate and a plate made of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, or polysulfone are preferable. For a glass substrate, soda-lime glass or alkali-free glass is used, and the thickness is sufficient to maintain mechanical strength, so that it may be, for example, 0.2 mm or more. The upper limit of the thickness is, for example, 2 mm or less, preferably 1 mm or less. As for the material of the glass, it is better to have fewer ions eluted from the glass, so alkali-free glass is preferable, but soda-lime glass with a barrier coat such as SiO ₂ is also commercially available, and this can be used. In addition, in order to improve the gas barrier properties, the substrate 101 may be provided with a gas barrier film such as a dense silicon oxide film on at least one side, and it is preferable to provide a gas barrier film, especially when a synthetic resin plate, film or sheet with poor gas barrier properties is used as the substrate 101.

<Anode in Organic Electroluminescent Device>
The anode 102 plays a role in injecting holes into the light-emitting layer 105. When the hole injection layer 103 and/or the hole transport layer 104 are provided between the anode 102 and the light-emitting layer 105, holes are injected into the light-emitting layer 105 via these layers.

Materials for forming the anode 102 include inorganic and organic compounds. Inorganic compounds include, for example, metals (aluminum, gold, silver, nickel, palladium, chromium, etc.), metal oxides (indium oxide, tin oxide, indium-tin oxide (ITO), indium-zinc oxide (IZO), etc.), metal halides (copper iodide, etc.), copper sulfide, carbon black, ITO glass, and Nesa glass. Organic compounds include, for example, polythiophenes such as poly(3-methylthiophene), conductive polymers such as polypyrrole and polyaniline. In addition, materials that are used as anodes in organic EL elements can be appropriately selected and used.

The resistance of the transparent electrode is not limited as long as it can supply sufficient current to light the light-emitting element, but a low resistance is desirable from the viewpoint of the power consumption of the light-emitting element. For example, an ITO substrate of 300 Ω/□ or less will function as an element electrode, but since it is now possible to supply substrates of around 10 Ω/□, it is particularly desirable to use a low resistance product of, for example, 100 to 5 Ω/□, preferably 50 to 5 Ω/□. The thickness of the ITO can be selected arbitrarily according to the resistance value, but it is usually used in the range of 50 to 300 nm.

<Hole injection layer and hole transport layer in organic electroluminescence device>
The hole injection layer 103 plays a role of efficiently injecting holes moving from the anode 102 into the light emitting layer 105 or the hole transport layer 104. The hole transport layer 104 plays a role of efficiently transporting holes injected from the anode 102 or holes injected from the anode 102 through the hole injection layer 103 to the light emitting layer 105. The hole injection layer 103 and the hole transport layer 104 are each formed by laminating and mixing one or more types of hole injection/transport materials, or by a mixture of a hole injection/transport material and a polymer binder. Alternatively, a layer may be formed by adding an inorganic salt such as iron (III) chloride to the hole injection/transport material.

A hole injection/transport material needs to be able to efficiently inject and transport holes from the positive electrode between electrodes to which an electric field is applied, and it is desirable for the material to have high hole injection efficiency and efficiently transport the injected holes. To achieve this, it is preferable for the material to have a low ionization potential, high hole mobility, and excellent stability, and to be one that is unlikely to generate impurities that act as traps during manufacture and use.

As the material for forming the hole injection layer 103 and the hole transport layer 104, any compound can be selected from compounds conventionally used as charge transport materials for holes in photoconductive materials, p-type semiconductors, and known compounds used in hole injection layers and hole transport layers of organic EL elements. Specific examples thereof include carbazole derivatives (N-phenylcarbazole, polyvinylcarbazole, etc.), biscarbazole derivatives such as bis(N-arylcarbazole) or bis(N-alkylcarbazole), triarylamine derivatives (polymers having an aromatic tertiary amino in the main chain or side chain, 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane, N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diaminobiphenyl, N,N'-diphenyl-N,N'-dinaphthyl-4,4'-diaminobiphenyl, N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine, N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine, N ⁴ ,N ^{4 '} -diphenyl-N ⁴ ,N ^{4 '} -Bis(9-phenyl-9H-carbazol-3-yl)-[1,1'-biphenyl]-4,4'-diamine, N ⁴ , N ⁴ , N ^{4 '} , N ^{4 '} -tetra[1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine, triphenylamine derivatives such as 4,4',4"-tris(3-methylphenyl(phenyl)amino)triphenylamine, starburst amine derivatives, etc.), stilbene derivatives, phthalocyanine derivatives (metal-free, copper phthalocyanine, etc.), pyrazoline derivatives, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, quinoxaline derivatives (for example, 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-hexacarbonitrile, etc.), heterocyclic compounds such as porphyrin derivatives, polysilanes, etc. As for polymers, polycarbonates and styrene derivatives having the above-mentioned monomers in the side chains, polyvinylcarbazole, polysilane, etc. are preferable, but there is no particular limitation as long as they are compounds that can form a thin film required for producing a light-emitting element, can inject holes from the anode, and can transport holes.

It is also known that the electrical conductivity of organic semiconductors is strongly influenced by their doping. Such organic semiconductor matrix substances consist of compounds with good electron donating or accepting properties. For doping with electron donating substances, strong electron acceptors such as tetracyanoquinone dimethane (TCNQ) or 2,3,5,6-tetrafluorotetracyano-1,4-benzoquinone dimethane (F4TCNQ) are known (see, for example, the literature "M. Pfeiffer, A. Beyer, T. Fritz, K. Leo, Appl. Phys. Lett., 73(22), 3202-3204 (1998)" and the literature "J. Blochwitz, M. Pheiffer, T. Fritz, K. Leo, Appl. Phys. Lett., 73(6), 729-731 (1998)"). These generate so-called holes by an electron transfer process in an electron-donating base material (hole transport material). The conductivity of the base material varies considerably depending on the number and mobility of the holes. Matrix materials with hole transport properties are known, for example, benzidine derivatives (such as TPD) or starburst amine derivatives (such as TDATA), or certain metal phthalocyanines (especially zinc phthalocyanine (ZnPc)) (JP 2005-167175 A).

<Light-emitting layer in organic electroluminescent device>
The light-emitting layer 105 is a layer that emits light by recombining holes injected from the anode 102 and electrons injected from the cathode 108 between electrodes to which an electric field is applied. The material for the light-emitting layer 105 may be a compound that is excited to emit light by the recombination of holes and electrons (light-emitting compound), and is preferably a compound that can be formed into a stable thin film shape and exhibits strong light-emitting (fluorescence) efficiency in a solid state.

The light-emitting layer may be a single layer or multiple layers, each of which is formed from light-emitting layer materials (host material, dopant material). The host material and dopant material may each be one type, or a combination of multiple types. The dopant material may be contained entirely in the host material, or may be contained partially in the host material. As a doping method, the dopant material can be formed by co-evaporation with the host material, but it may also be mixed with the host material in advance and then simultaneously evaporated, or mixed with the host material together with an organic solvent and then formed into a film by a wet film-forming method.

The amount of the host material used varies depending on the type of host material, and can be determined according to the characteristics of the host material. The amount of the host material used is preferably 50 to 99.999% by weight, more preferably 80 to 99.95% by weight, and even more preferably 90 to 99.9% by weight, of the total light-emitting layer material.

The amount of dopant material used varies depending on the type of dopant material, and may be determined according to the characteristics of the dopant material. The amount of dopant used is preferably 0.001 to 50% by weight of the total light-emitting layer material, more preferably 0.05 to 20% by weight, and even more preferably 0.1 to 10% by weight. The above ranges are preferable in that they can prevent, for example, concentration quenching.

Examples of host materials include condensed ring derivatives such as anthracene, pyrene, dibenzochrysene, and fluorene, which have long been known as light emitters, bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives, tetraphenylbutadiene derivatives, and cyclopentadiene derivatives. In particular, anthracene-based compounds, fluorene-based compounds, and dibenzochrysene-based compounds are preferred.

<Electron Injection Layer and Electron Transport Layer in Organic Electroluminescent Device>
The electron injection layer 107 plays a role of efficiently injecting electrons moving from the cathode 108 into the light emitting layer 105 or the electron transport layer 106. The electron transport layer 106 plays a role of efficiently transporting electrons injected from the cathode 108 or electrons injected from the cathode 108 via the electron injection layer 107 to the light emitting layer 105. The electron transport layer 106 and the electron injection layer 107 are each formed by laminating or mixing one or more types of electron transport/injection materials, or by a mixture of an electron transport/injection material and a polymer binder.

The electron injection/transport layer is a layer that is responsible for injecting electrons from the cathode and transporting the electrons. It is desirable that the electron injection efficiency is high and that the injected electrons are efficiently transported. For this purpose, it is preferable that the material has a large electron affinity, a large electron mobility, excellent stability, and is unlikely to generate impurities that become traps during manufacture and use. However, when considering the balance of hole and electron transport, if the material mainly plays a role of efficiently preventing holes from the anode from flowing to the cathode without recombining, even if the electron transport ability is not so high, it has the effect of improving the luminous efficiency equivalent to a material with a high electron transport ability. Therefore, the electron injection/transport layer in this embodiment may also include the function of a layer that can efficiently block the movement of holes.

The material (electron transport material) forming the electron transport layer 106 or the electron injection layer 107 can be arbitrarily selected from compounds conventionally used as electron transfer compounds in photoconductive materials and known compounds used in the electron injection layer and electron transport layer of organic EL elements. In the present invention, the polycyclic aromatic compound represented by the above general formula (1) and its polymer can be used as the electron transport material and electron injection material.

In general, materials used in the electron transport layer or electron injection layer preferably contain at least one selected from compounds consisting of aromatic rings or heteroaromatic rings composed of one or more atoms selected from carbon, hydrogen, oxygen, sulfur, silicon, and phosphorus, pyrrole derivatives and their condensed ring derivatives, and metal complexes having electron-accepting nitrogen. Specific examples include condensed ring aromatic ring derivatives such as naphthalene and anthracene, styryl aromatic ring derivatives such as 4,4'-bis(diphenylethenyl)biphenyl, perinone derivatives, coumarin derivatives, naphthalimide derivatives, quinone derivatives such as anthraquinone and diphenoquinone, phosphorus oxide derivatives, carbazole derivatives, and indole derivatives. Examples of metal complexes having electron-accepting nitrogen include hydroxyazole complexes such as hydroxyphenyloxazole complexes, azomethine complexes, tropolone metal complexes, flavonol metal complexes, and benzoquinoline metal complexes. These materials can be used alone or in combination with different materials.

Specific examples of other electron transport compounds include pyridine derivatives, naphthalene derivatives, anthracene derivatives, phenanthroline derivatives, perinone derivatives, coumarin derivatives, naphthalimide derivatives, anthraquinone derivatives, diphenoquinone derivatives, diphenylquinone derivatives, perylene derivatives, oxadiazole derivatives (such as 1,3-bis[(4-t-butylphenyl)1,3,4-oxadiazolyl]phenylene), thiophene derivatives, triazole derivatives (such as N-naphthyl-2,5-diphenyl-1,3,4-triazole), thiadiazole derivatives, metal complexes of oxine derivatives, quinolinol-based metal complexes, quinoxaline derivatives, polymers of quinoxaline derivatives, benzazole compounds, gallium complexes, pyrazole derivatives, perfluorinated phenylene derivatives, triazine derivatives, and pyridine derivatives. Examples of the compound include arylazine derivatives, benzoquinoline derivatives (2,2'-bis(benzo[h]quinolin-2-yl)-9,9'-spirobifluorene, etc.), imidazopyridine derivatives, borane derivatives, benzimidazole derivatives (tris(N-phenylbenzimidazol-2-yl)benzene, etc.), benzoxazole derivatives, benzothiazole derivatives, quinoline derivatives, oligopyridine derivatives such as terpyridine, bipyridine derivatives, terpyridine derivatives (1,3-bis(4'-(2,2':6'2"-terpyridinyl))benzene, etc.), naphthyridine derivatives (bis(1-naphthyl)-4-(1,8-naphthyridin-2-yl)phenylphosphine oxide, etc.), aldazine derivatives, carbazole derivatives, indole derivatives, phosphorus oxide derivatives, and bisstyryl derivatives.

Metal complexes having an electron-accepting nitrogen can also be used, such as hydroxyazole complexes such as quinolinol metal complexes and hydroxyphenyloxazole complexes, azomethine complexes, tropolone metal complexes, flavonol metal complexes, and benzoquinoline metal complexes.

The above-mentioned materials can be used alone or in combination with different materials.

Among the above-mentioned materials, borane derivatives, pyridine derivatives, fluoranthene derivatives, BO-based derivatives, anthracene derivatives, benzofluorene derivatives, phosphine oxide derivatives, pyrimidine derivatives, carbazole derivatives, triazine derivatives, benzimidazole derivatives, phenanthroline derivatives, and quinolinol-based metal complexes are preferred.

上記式（ＥＴＭ－１）中、Ｒ^１１およびＲ^１２は、それぞれ独立して、水素、アルキル、シクロアルキル、置換されていてもよいアリール、置換されているシリル、置換されていてもよい窒素含有複素環、またはシアノの少なくとも一つであり、Ｒ^１３～Ｒ^１６は、それぞれ独立して、置換されていてもよいアルキル、置換されていてもよいシクロアルキルまたは置換されていてもよいアリールであり、Ｘは、置換されていてもよいアリーレンであり、Ｙは、置換されていてもよい炭素数１６以下のアリール、置換されているボリル、または置換されていてもよいカルバゾリルであり、そして、ｎはそれぞれ独立して０～３の整数である。また、「置換されていてもよい」または「置換されている」場合の置換基としては、アリール、ヘテロアリール、アルキルまたはシクロアルキルなどがあげられる。 <Borane derivatives>
The borane derivative is, for example, a compound represented by the following general formula (ETM-1), and is disclosed in detail in JP-A-2007-27587.

In the above formula (ETM-1), R ¹¹ and R ¹² are each independently at least one of hydrogen, alkyl, cycloalkyl, optionally substituted aryl, substituted silyl, optionally substituted nitrogen-containing heterocycle, or cyano, R ¹³ to R ¹⁶ are each independently optionally substituted alkyl, optionally substituted cycloalkyl, or optionally substituted aryl, X is optionally substituted arylene, Y is optionally substituted aryl having 16 or less carbon atoms, substituted boryl, or optionally substituted carbazolyl, and n is each independently an integer of 0 to 3. In addition, examples of the substituent in the case of "optionally substituted" or "substituted" include aryl, heteroaryl, alkyl, and cycloalkyl.

式（ＥＴＭ－１－１）中、Ｒ^１１およびＲ^１２は、それぞれ独立して、水素、アルキル、シクロアルキル、置換されていてもよいアリール、置換されているシリル、置換されていてもよい窒素含有複素環、またはシアノの少なくとも一つであり、Ｒ^１３～Ｒ^１６は、それぞれ独立して、置換されていてもよいアルキル、置換されていてもよいシクロアルキルまたは置換されていてもよいアリールであり、Ｒ^２１およびＲ^２２は、それぞれ独立して、水素、アルキル、シクロアルキル置換されていてもよいアリール、置換されているシリル、置換されていてもよい窒素含有複素環、またはシアノの少なくとも一つであり、Ｘ^１は、置換されていてもよい炭素数２０以下のアリーレンであり、ｎはそれぞれ独立して０～３の整数であり、そして、ｍはそれぞれ独立して０～４の整数である。また、「置換されていてもよい」または「置換されている」場合の置換基としては、アリール、ヘテロアリール、アルキルまたはシクロアルキルなどがあげられる。

式（ＥＴＭ－１－２）中、Ｒ^１１およびＲ^１２は、それぞれ独立して、水素、アルキル、シクロアルキル、置換されていてもよいアリール、置換されているシリル、置換されていてもよい窒素含有複素環、またはシアノの少なくとも一つであり、Ｒ^１３～Ｒ^１６は、それぞれ独立して、置換されていてもよいアルキル、置換されていてもよいシクロアルキルまたは置換されていてもよいアリールであり、Ｘ^１は、置換されていてもよい炭素数２０以下のアリーレンであり、そして、ｎはそれぞれ独立して０～３の整数である。また、「置換されていてもよい」または「置換されている」場合の置換基としては、アリール、ヘテロアリール、アルキルまたはシクロアルキルなどがあげられる。 Among the compounds represented by the above general formula (ETM-1), compounds represented by the following general formula (ETM-1-1) and compounds represented by the following general formula (ETM-1-2) are preferred.

In formula (ETM-1-1), R ¹¹ and R ¹² are each independently at least one of hydrogen, alkyl, cycloalkyl, optionally substituted aryl, substituted silyl, optionally substituted nitrogen-containing heterocycle, or cyano, R ¹³ to R ¹⁶ are each independently at least one of optionally substituted alkyl, optionally substituted cycloalkyl, or optionally substituted aryl, R ²¹ and R ²² are each independently at least one of hydrogen, alkyl, optionally substituted cycloalkyl aryl, substituted silyl, optionally substituted nitrogen-containing heterocycle, or cyano, X ¹ is an optionally substituted arylene having 20 or less carbon atoms, n is each independently an integer of 0 to 3, and m is each independently an integer of 0 to 4. In addition, examples of the substituent in the case of "optionally substituted" or "substituted" include aryl, heteroaryl, alkyl, and cycloalkyl.

In formula (ETM-1-2), R ¹¹ and R ¹² each independently represent at least one of hydrogen, alkyl, cycloalkyl, optionally substituted aryl, substituted silyl, optionally substituted nitrogen-containing heterocycle, or cyano, R ¹³ to R ¹⁶ each independently represent optionally substituted alkyl, optionally substituted cycloalkyl, or optionally substituted aryl, X ¹ is an optionally substituted arylene having 20 or less carbon atoms, and each n is independently an integer of 0 to 3. Examples of the substituent in the case of being "optionally substituted" or "substituted" include aryl, heteroaryl, alkyl, and cycloalkyl.

（各式中、Ｒ^ａは、それぞれ独立してアルキル基、シクロアルキル基または置換されていてもよいフェニル基である。） Specific examples of ^X1 include divalent groups represented by any one of the following formulae (X-1) to (X-9).

(In each formula, R ^a is independently an alkyl group, a cycloalkyl group, or an optionally substituted phenyl group.)

Specific examples of the borane derivative include the following compounds:

This borane derivative can be produced using known raw materials and known synthesis methods.

<Pyridine derivatives>
The pyridine derivative is, for example, a compound represented by the following formula (ETM-2), and is preferably a compound represented by formula (ETM-2-1) or (ETM-2-2).

φ is an n-valent aryl ring (preferably an n-valent benzene ring, naphthalene ring, anthracene ring, fluorene ring, benzofluorene ring, phenalene ring, phenanthrene ring or triphenylene ring), and n is an integer from 1 to 4.

In the above formula (ETM-2-1), R ¹¹ to R ¹⁸ are each independently hydrogen, alkyl (preferably alkyl having 1 to 24 carbon atoms), cycloalkyl (preferably cycloalkyl having 3 to 12 carbon atoms) or aryl (preferably aryl having 6 to 30 carbon atoms).

In the above formula (ETM-2-2), R ¹¹ and R ¹² are each independently hydrogen, alkyl (preferably alkyl having 1 to 24 carbon atoms), cycloalkyl (preferably cycloalkyl having 3 to 12 carbon atoms) or aryl (preferably aryl having 6 to 30 carbon atoms), and R ¹¹ and R ¹² may be bonded to form a ring.

In each formula, the "pyridine-based substituent" is any of the following formulae (Py-1) to (Py-15), and each pyridine-based substituent may be independently substituted with an alkyl having 1 to 4 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms. In addition, the pyridine-based substituent may be bonded to the φ, anthracene ring, or fluorene ring in each formula via a phenylene group or naphthylene group.

The pyridine-based substituent is any one of the above formulae (Py-1) to (Py-15), and among these, any one of the following formulae (Py-21) to (Py-44) is preferable.

At least one hydrogen in each pyridine derivative may be replaced with deuterium, and one of the two "pyridine-based substituents" in the above formulas (ETM-2-1) and (ETM-2-2) may be replaced with an aryl.

The "alkyl" in R ¹¹ to R ¹⁸ may be either linear or branched, and examples thereof include linear alkyl having 1 to 24 carbon atoms or branched alkyl having 3 to 24 carbon atoms. A preferred "alkyl" is an alkyl having 1 to 18 carbon atoms (branched alkyl having 3 to 18 carbon atoms). A more preferred "alkyl" is an alkyl having 1 to 12 carbon atoms (branched alkyl having 3 to 12 carbon atoms). An even more preferred "alkyl" is an alkyl having 1 to 6 carbon atoms (branched alkyl having 3 to 6 carbon atoms). An especially preferred "alkyl" is an alkyl having 1 to 4 carbon atoms (branched alkyl having 3 to 4 carbon atoms).

Specific examples of "alkyl" include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, n-octyl, t-octyl, 1-methylheptyl, Examples include 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 2,6-dimethyl-4-heptyl, 3,5,5-trimethylhexyl, n-decyl, n-undecyl, 1-methyldecyl, n-dodecyl, n-tridecyl, 1-hexylheptyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, and n-eicosyl.

For the alkyl having 1 to 4 carbon atoms to be substituted on the pyridine-based substituent, the above description of alkyl can be cited.

The "cycloalkyl" in R ¹¹ to R ¹⁸ is, for example, a cycloalkyl having 3 to 12 carbon atoms. A preferred "cycloalkyl" is a cycloalkyl having 3 to 10 carbon atoms. A more preferred "cycloalkyl" is a cycloalkyl having 3 to 8 carbon atoms. An even more preferred "cycloalkyl" is a cycloalkyl having 3 to 6 carbon atoms.
Specific examples of "cycloalkyl" include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclopentyl, cycloheptyl, methylcyclohexyl, cyclooctyl, and dimethylcyclohexyl.

For the cycloalkyl having 5 to 10 carbon atoms to be substituted on the pyridine-based substituent, the above description of cycloalkyl can be cited.

As the "aryl" in R ¹¹ to R ¹⁸ , the preferred aryl is an aryl having 6 to 30 carbon atoms, the more preferred aryl is an aryl having 6 to 18 carbon atoms, the further more preferred aryl is an aryl having 6 to 14 carbon atoms, and the most preferred aryl is an aryl having 6 to 12 carbon atoms.

Specific examples of "aryls having 6 to 30 carbon atoms" include monocyclic aryls such as phenyl, fused bicyclic aryls such as (1-, 2-)naphthyl, fused tricyclic aryls such as acenaphthylene-(1-, 3-, 4-, 5-)yl, fluorene-(1-, 2-, 3-, 4-, 9-)yl, phenalene-(1-, 2-)yl, and (1-, 2-, 3-, 4-, 9-)phenanthryl, fused tetracyclic aryls such as triphenylene-(1-, 2-)yl, pyrene-(1-, 2-, 4-)yl, and naphthacene-(1-, 2-, 5-)yl, and fused pentacyclic aryls such as perylene-(1-, 2-, 3-)yl and pentacene-(1-, 2-, 5-, 6-)yl.

Preferred "aryl having 6 to 30 carbon atoms" include phenyl, naphthyl, phenanthryl, chrysenyl, and triphenylenyl, more preferably phenyl, 1-naphthyl, 2-naphthyl, and phenanthryl, and particularly preferably phenyl, 1-naphthyl, and 2-naphthyl.

In the above formula (ETM-2-2), R ¹¹ and R ¹² may be bonded to form a ring, and as a result, cyclobutane, cyclopentane, cyclopentene, cyclopentadiene, cyclohexane, fluorene, indene, or the like may be spiro-bonded to the five-membered ring of the fluorene skeleton.

Specific examples of the pyridine derivative include the following compounds:

This pyridine derivative can be produced using known raw materials and known synthesis methods.

<Fluoranthene derivatives>
The fluoranthene derivative is, for example, a compound represented by the following general formula (ETM-3), and is disclosed in detail in WO 2010/134352.

In the above formula (ETM-3), X ¹² to X ²¹ each represent hydrogen, halogen, linear, branched or cyclic alkyl, linear, branched or cyclic alkoxy, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl. In the case where a group is substituted, examples of the substituent include aryl, heteroaryl, alkyl, and cycloalkyl.

Specific examples of the fluoranthene derivative include the following compounds:

<BO derivatives>
The BO derivative is, for example, a polycyclic aromatic compound represented by the following formula (ETM-4) or a polymer of a polycyclic aromatic compound having a plurality of structures represented by the following formula (ETM-4).

R ¹ to R ¹¹ are each independently hydrogen, aryl, heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl (two aryls may be bonded via a single bond or a linking group), alkyl, cycloalkyl, alkoxy, or aryloxy, in which at least one hydrogen may be substituted with an aryl, heteroaryl, alkyl, or cycloalkyl.

Adjacent groups among R ¹ to R ¹¹ may be bonded to each other to form an aryl ring or a heteroaryl ring together with the ring a, ring b, or ring c, and at least one hydrogen atom in the formed ring may be substituted with an aryl, heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl (two aryls may be bonded via a single bond or a linking group), alkyl, cycloalkyl, alkoxy, or aryloxy, and at least one hydrogen atom in these rings may be substituted with an aryl, heteroaryl, alkyl, or cycloalkyl.

Additionally, at least one hydrogen in the compound or structure represented by formula (ETM-4) may be replaced with a halogen or deuterium.

For an explanation of the substituents and ring formation form in formula (ETM-4), as well as the multimers formed by combining multiple structures of formula (ETM-4), the explanations of the polycyclic aromatic compounds and their multimers represented by general formula (1) or formula (2) above may be cited.

Specific examples of the BO derivative include the following compounds:

This BO derivative can be produced using known raw materials and known synthesis methods.

<Anthracene derivatives>
One example of the anthracene derivative is a compound represented by the following formula (ETM-5-1).

Each Ar is independently a divalent benzene or naphthalene, and each of R ¹ to R ⁴ is independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

Each Ar can be independently selected from divalent benzene or naphthalene, and the two Ars may be different or the same, but are preferably the same from the viewpoint of ease of synthesis of the anthracene derivative. Ar is bonded to pyridine to form a "moiety consisting of Ar and pyridine", and this moiety is bonded to anthracene as a group represented by any one of the following formulas (Py-1) to (Py-12), for example.

Among these groups, a group represented by any one of the above formulas (Py-1) to (Py-9) is preferred, and a group represented by any one of the above formulas (Py-1) to (Py-6) is more preferred. The two "sites consisting of Ar and pyridine" bonded to anthracene may have the same or different structures, but from the viewpoint of ease of synthesis of anthracene derivatives, it is preferable that they have the same structure. However, from the viewpoint of element characteristics, it is preferable that the structures of the two "sites consisting of Ar and pyridine" are the same or different.

The alkyl having 1 to 6 carbon atoms in R ¹ to R ⁴ may be either linear or branched. That is, it is a linear alkyl having 1 to 6 carbon atoms or a branched alkyl having 3 to 6 carbon atoms. It is more preferably an alkyl having 1 to 4 carbon atoms (branched alkyl having 3 to 4 carbon atoms). Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, and 2-ethylbutyl, and methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, or t-butyl is preferred, and methyl, ethyl, or t-butyl is more preferred.

Specific examples of the cycloalkyl having 3 to 6 carbon atoms for R ¹ to R ⁴ include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclopentyl, cycloheptyl, methylcyclohexyl, cyclooctyl, and dimethylcyclohexyl.

The aryl having 6 to 20 carbon atoms in R ¹ to R ⁴ is preferably an aryl having 6 to 16 carbon atoms, more preferably an aryl having 6 to 12 carbon atoms, and particularly preferably an aryl having 6 to 10 carbon atoms.

Specific examples of "aryl having 6 to 20 carbon atoms" include monocyclic aryls such as phenyl, (o-, m-, p-) tolyl, (2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-) xylyl, mesityl (2,4,6-trimethylphenyl), (o-, m-, p-) cumenyl, bicyclic aryls such as (2-, 3-, 4-) biphenylyl, condensed bicyclic aryls such as (1-, 2-) naphthyl, tricyclic aryls such as terphenylyl (m-terphenyl-2'-yl, m-terphenyl-4'-yl, m-terphenyl-5'-yl, o-terphenyl-3'-yl, o-terphenyl-4'-yl, p-terphenyl-2'-yl, m-terphenyl-2-yl, m-terphenyl-3-yl, m ...4'-yl, p-terphenyl-2-yl, m-terphenyl-2-yl, m-terphenyl-3-yl, m-terphenyl-4'-yl, p-terphenyl-2-yl, m-terphenyl-4'-yl, p-terphenyl-2-yl, m-terphenyl-2-yl, m-terphenyl-3-yl aryl, o-terphenyl-4-yl, o-terphenyl-2-yl, o-terphenyl-3-yl, o-terphenyl-4-yl, p-terphenyl-2-yl, p-terphenyl-3-yl, p-terphenyl-4-yl; fused tricyclic aryls, anthracene-(1-,2-,9-)yl, acenaphthylene-(1-,3-,4-,5-)yl, fluorene-(1-,2-,3-,4-,9-)yl, phenalene-(1-,2-)yl, (1-,2-,3-,4-,9-)phenanthryl; fused tetracyclic aryls, triphenylene-(1-,2-)yl, pyrene-(1-,2-,4-)yl, tetracene-(1-,2-,5-)yl; fused pentacyclic aryls, perylene-(1-,2-,3-)yl, and the like.

Preferred "aryl having 6 to 20 carbon atoms" are phenyl, biphenylyl, terphenylyl, or naphthyl, more preferably phenyl, biphenylyl, 1-naphthyl, 2-naphthyl, or m-terphenyl-5'-yl, even more preferably phenyl, biphenylyl, 1-naphthyl, or 2-naphthyl, and most preferably phenyl.

One example of the anthracene derivative is a compound represented by the following formula (ETM-5-2).

Each Ar ¹ is independently a single bond, or a divalent benzene, naphthalene, anthracene, fluorene, or phenalene.

Each Ar ² is independently an aryl having 6 to 20 carbon atoms, and the same explanation as for "aryl having 6 to 20 carbon atoms" in the above formula (ETM-5-1) can be cited. An aryl having 6 to 16 carbon atoms is preferable, an aryl having 6 to 12 carbon atoms is more preferable, and an aryl having 6 to 10 carbon atoms is particularly preferable. Specific examples include phenyl, biphenylyl, naphthyl, terphenylyl, anthracenyl, acenaphthylenyl, fluorenyl, phenalenyl, phenanthryl, triphenylenyl, pyrenyl, tetracenyl, perylenyl, etc.

R ¹ to R ⁴ each independently represent hydrogen, alkyl having 1 to 6 carbon atoms, cycloalkyl having 3 to 6 carbon atoms, or aryl having 6 to 20 carbon atoms, and the explanation in the above formula (ETM-5-1) can be cited.

Specific examples of these anthracene derivatives include the following compounds.

These anthracene derivatives can be produced using known raw materials and known synthesis methods.

<Benzofluorene derivatives>
The benzofluorene derivative is, for example, a compound represented by the following formula (ETM-6).

Each Ar ¹ is independently an aryl having 6 to 20 carbon atoms, and the same explanation as for "aryl having 6 to 20 carbon atoms" in the above formula (ETM-5-1) can be cited. An aryl having 6 to 16 carbon atoms is preferable, an aryl having 6 to 12 carbon atoms is more preferable, and an aryl having 6 to 10 carbon atoms is particularly preferable. Specific examples include phenyl, biphenylyl, naphthyl, terphenylyl, anthracenyl, acenaphthylenyl, fluorenyl, phenalenyl, phenanthryl, triphenylenyl, pyrenyl, tetracenyl, perylenyl, etc.

Each Ar ² is independently hydrogen, an alkyl (preferably an alkyl having 1 to 24 carbon atoms), a cycloalkyl (preferably a cycloalkyl having 3 to 12 carbon atoms) or an aryl (preferably an aryl having 6 to 30 carbon atoms), and two Ar ² may be bonded to form a ring.

The "alkyl" in ^Ar2 may be either linear or branched, and examples thereof include linear alkyl having 1 to 24 carbon atoms or branched alkyl having 3 to 24 carbon atoms. A preferred "alkyl" is an alkyl having 1 to 18 carbon atoms (branched alkyl having 3 to 18 carbon atoms). A more preferred "alkyl" is an alkyl having 1 to 12 carbon atoms (branched alkyl having 3 to 12 carbon atoms). An even more preferred "alkyl" is an alkyl having 1 to 6 carbon atoms (branched alkyl having 3 to 6 carbon atoms). An especially preferred "alkyl" is an alkyl having 1 to 4 carbon atoms (branched alkyl having 3 to 4 carbon atoms). Specific examples of "alkyl" include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, and the like.

The "cycloalkyl" in ^Ar2 includes, for example, cycloalkyl having 3 to 12 carbon atoms. A preferred "cycloalkyl" is cycloalkyl having 3 to 10 carbon atoms. A more preferred "cycloalkyl" is cycloalkyl having 3 to 8 carbon atoms. An even more preferred "cycloalkyl" is cycloalkyl having 3 to 6 carbon atoms. Specific examples of "cycloalkyl" include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclopentyl, cycloheptyl, methylcyclohexyl, cyclooctyl, and dimethylcyclohexyl.

As the "aryl" in ^Ar2 , a preferable aryl is an aryl having 6 to 30 carbon atoms, a more preferable aryl is an aryl having 6 to 18 carbon atoms, an even more preferable aryl is an aryl having 6 to 14 carbon atoms, and an especially preferable aryl is an aryl having 6 to 12 carbon atoms.

Specific examples of "aryl having 6 to 30 carbon atoms" include phenyl, naphthyl, acenaphthylenyl, fluorenyl, phenalenyl, phenanthryl, triphenylenyl, pyrenyl, naphthacenyl, perylenyl, pentacenyl, etc.

Two ^Ar2 may be bonded to form a ring, and as a result, cyclobutane, cyclopentane, cyclopentene, cyclopentadiene, cyclohexane, fluorene, indene, or the like may be spiro-bonded to the five-membered ring of the fluorene skeleton.

Specific examples of the benzofluorene derivative include the following compounds:

This benzofluorene derivative can be produced using known raw materials and known synthesis methods.

Ｒ^５は、置換または無置換の、炭素数１～２０のアルキル、炭素数３～２０のシクロアルキル、炭素数６～２０のアリールまたは炭素数５～２０のヘテロアリールであり、
Ｒ^６は、ＣＮ、置換または無置換の、炭素数１～２０のアルキル、炭素数３～２０のシクロアルキル、炭素数１～２０のヘテロアルキル、炭素数６～２０のアリール、炭素数５～２０のヘテロアリール、炭素数１～２０のアルコキシまたは炭素数６～２０のアリールオキシであり、
Ｒ^７およびＲ^８は、それぞれ独立して、置換または無置換の、炭素数６～２０のアリールまたは炭素数５～２０のヘテロアリールであり、
Ｒ^９は酸素または硫黄であり、
ｊは０または１であり、ｋは０または１であり、ｒは０～４の整数であり、ｑは１～３の整数である。
ここで、置換されている場合の置換基としては、アリール、ヘテロアリール、アルキルまたはシクロアルキルなどがあげられる。 <Phosphine oxide derivatives>
The phosphine oxide derivative is, for example, a compound represented by the following formula (ETM-7-1). Details are also described in WO 2013/079217.

^R5 is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 5 to 20 carbon atoms;
R ⁶ is CN, a substituted or unsubstituted alkyl having 1 to 20 carbon atoms, a cycloalkyl having 3 to 20 carbon atoms, a heteroalkyl having 1 to 20 carbon atoms, an aryl having 6 to 20 carbon atoms, a heteroaryl having 5 to 20 carbon atoms, an alkoxy having 1 to 20 carbon atoms, or an aryloxy having 6 to 20 carbon atoms;
R ⁷ and R ⁸ are each independently a substituted or unsubstituted aryl having 6 to 20 carbon atoms or a heteroaryl having 5 to 20 carbon atoms;
^R9 is oxygen or sulfur;
j is 0 or 1, k is 0 or 1, r is an integer of 0 to 4, and q is an integer of 1 to 3.
When substituted, the substituent may be an aryl, heteroaryl, alkyl or cycloalkyl.

The phosphine oxide derivative may be, for example, a compound represented by the following formula (ETM-7-2).

R ¹ to R ³ may be the same or different and are selected from hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an alkoxy group, an alkylthio group, a cycloalkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heterocyclic group, a halogen, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an amino group, a nitro group, a silyl group, and a condensed ring formed between adjacent substituents.

Ar ¹ may be the same or different and is an arylene group or a heteroarylene group. Ar ² may be the same or different and is an aryl group or a heteroaryl group. However, at least one of Ar ¹ and Ar ² has a substituent or forms a condensed ring with the adjacent substituent. n is an integer of 0 to 3, when n is 0, there is no unsaturated structural portion, and when n is 3, R ¹ does not exist.

Of these substituents, the alkyl group refers to a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group, or a butyl group, which may be unsubstituted or substituted. If the group is substituted, there is no particular limit to the type of substituent, and examples of the substituent include an alkyl group, an aryl group, and a heterocyclic group, which is also the case in the following descriptions. The number of carbon atoms in the alkyl group is not particularly limited, but is usually in the range of 1 to 20 from the standpoint of availability and cost.

A cycloalkyl group refers to a saturated alicyclic hydrocarbon group such as cyclopropyl, cyclohexyl, norbornyl, or adamantyl, which may be unsubstituted or substituted. The number of carbon atoms in the alkyl group is not particularly limited, but is usually in the range of 3 to 20.

The term "aralkyl group" refers to an aromatic hydrocarbon group linked via an aliphatic hydrocarbon, such as a benzyl group or a phenylethyl group, and both the aliphatic and aromatic hydrocarbons may be unsubstituted or substituted. The number of carbon atoms in the aliphatic portion is not particularly limited, but is usually in the range of 1 to 20.

Alkenyl groups refer to unsaturated aliphatic hydrocarbon groups containing a double bond, such as vinyl groups, allyl groups, and butadienyl groups, which may be unsubstituted or substituted. The number of carbon atoms in an alkenyl group is not particularly limited, but is usually in the range of 2 to 20.

Furthermore, a cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond, such as a cyclopentenyl group, a cyclopentadienyl group, or a cyclohexene group, which may be unsubstituted or substituted.

Alkynyl groups refer to unsaturated aliphatic hydrocarbon groups containing a triple bond, such as acetylenyl groups, which may be unsubstituted or substituted. The number of carbon atoms in an alkynyl group is not particularly limited, but is usually in the range of 2 to 20.

Alkoxy groups refer to aliphatic hydrocarbon groups, such as methoxy groups, that are linked via an ether bond, and the aliphatic hydrocarbon groups may be unsubstituted or substituted. The number of carbon atoms in the alkoxy group is not particularly limited, but is usually in the range of 1 to 20.

An alkylthio group is a group in which the oxygen atom of the ether bond of an alkoxy group is replaced with a sulfur atom.

A cycloalkylthio group is a group in which the oxygen atom of the ether bond of a cycloalkoxy group is replaced with a sulfur atom.

The aryl ether group refers to an aromatic hydrocarbon group, such as a phenoxy group, that is linked via an ether bond, and the aromatic hydrocarbon group may be unsubstituted or substituted. The number of carbon atoms in the aryl ether group is not particularly limited, but is usually in the range of 6 to 40.

An aryl thioether group is a group in which the oxygen atom of the ether bond of an aryl ether group is replaced with a sulfur atom.

An aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, or a pyrenyl group. The aryl group may be unsubstituted or substituted. The number of carbon atoms in the aryl group is not particularly limited, but is usually in the range of 6 to 40.

The heterocyclic group refers to a cyclic structural group having atoms other than carbon, such as a furanyl group, a thiophenyl group, an oxazolyl group, a pyridyl group, a quinolinyl group, or a carbazolyl group, which may be unsubstituted or substituted. The number of carbon atoms in the heterocyclic group is not particularly limited, but is usually in the range of 2 to 30.

Halogen refers to fluorine, chlorine, bromine, and iodine.

The aldehyde group, carbonyl group, and amino group may also include groups substituted with aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, heterocycles, etc.

In addition, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and heterocycles may be unsubstituted or substituted.

The silyl group refers to a silicon compound group such as a trimethylsilyl group, which may be unsubstituted or substituted. The number of carbon atoms in the silyl group is not particularly limited, but is usually in the range of 3 to 20. The number of silicon atoms is usually 1 to 6.

The fused ring formed between adjacent substituents is, for example, a conjugated or non-conjugated fused ring formed between Ar ¹ and R ² , Ar ¹ and R ³ , Ar ² and R ² , Ar ² and R ³ , R ² and R ³ , Ar ¹ and Ar ² , etc. Here, when n is 1, two R ^1s may form a conjugated or non-conjugated fused ring. These fused rings may contain a nitrogen, oxygen, or sulfur atom in the ring structure, and may be further fused with another ring.

Specific examples of the phosphine oxide derivative include the following compounds:

This phosphine oxide derivative can be produced using known raw materials and known synthesis methods.

<Pyrimidine derivatives>
The pyrimidine derivative is, for example, a compound represented by the following formula (ETM-8), preferably a compound represented by the following formula (ETM-8-1). Details are also described in WO 2011/021689.

Each Ar is independently an optionally substituted aryl or an optionally substituted heteroaryl. n is an integer from 1 to 4, preferably an integer from 1 to 3, and more preferably 2 or 3.

The "aryl" in "optionally substituted aryl" includes, for example, aryl having 6 to 30 carbon atoms, preferably aryl having 6 to 24 carbon atoms, more preferably aryl having 6 to 20 carbon atoms, and even more preferably aryl having 6 to 12 carbon atoms.

Specific examples of "aryl" include monocyclic aryl phenyl, bicyclic aryl (2-, 3-, 4-) biphenylyl, condensed bicyclic aryl (1-, 2-) naphthyl, tricyclic aryl terphenylyl (m-terphenyl-2'-yl, m-terphenyl-4'-yl, m-terphenyl-5'-yl, o-terphenyl-3'-yl, o-terphenyl-4'-yl, p-terphenyl-2'-yl, m-terphenyl-2-yl, m-terphenyl-3-yl, m-terphenyl-4-yl, o-terphenyl-2-yl, o-terphenyl-3-yl, o-terphenyl-4-yl, p-terphenyl-2-yl, p-terphenyl-3-yl, p-terphenyl-4-yl), condensed tricyclic aryl Examples of the aryl include acenaphthylene-(1-,3-,4-,5-)yl, fluorene-(1-,2-,3-,4-,9-)yl, phenalene-(1-,2-)yl, and (1-,2-,3-,4-,9-)phenanthryl; the tetracyclic aryl is quaterphenylyl (5'-phenyl-m-terphenyl-2-yl, 5'-phenyl-m-terphenyl-3-yl, 5'-phenyl-m-terphenyl-4-yl, and m-quaterphenylyl); the condensed tetracyclic aryl is triphenylene-(1-,2-)yl, pyrene-(1-,2-,4-)yl, and naphthacene-(1-,2-,5-)yl; and the condensed pentacyclic aryl is perylene-(1-,2-,3-)yl and pentacene-(1-,2-,5-,6-)yl.

Examples of the "heteroaryl" in "optionally substituted heteroaryl" include heteroaryls having 2 to 30 carbon atoms, preferably heteroaryls having 2 to 25 carbon atoms, more preferably heteroaryls having 2 to 20 carbon atoms, even more preferably heteroaryls having 2 to 15 carbon atoms, and particularly preferably heteroaryls having 2 to 10 carbon atoms. Examples of heteroaryls include heterocycles containing, in addition to carbon, 1 to 5 heteroatoms selected from oxygen, sulfur, and nitrogen as ring-constituting atoms.

Specific examples of heteroaryl include furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, oxadiazolyl, furazanyl, thiadiazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, benzofuranyl, isobenzofuranyl, benzo[b]thienyl, indolyl, isoindolyl, 1H-indazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, 1H-benzotriazolyl, quinolyl, isoquinolyl, cinnolyl, quinazolyl, quinoxalinyl, phthalazinyl, naphthyridinyl, purinyl, pteridinyl, carbazolyl, acridinyl, phenoxazinyl, phenothiazinyl, phenazinyl, phenoxathiinyl, thianthrenyl, and indolizinyl.

In addition, the above aryl and heteroaryl may be substituted, for example, by the above aryl and heteroaryl, respectively.

Specific examples of the pyrimidine derivative include the following compounds:

This pyrimidine derivative can be produced using known raw materials and known synthesis methods.

<Carbazole derivatives>
The carbazole derivative is, for example, a compound represented by the following formula (ETM-9), or a multimer in which a plurality of such compounds are bonded together via single bonds, etc. Details are described in U.S. Publication No. 2014/0197386.

Each Ar is independently an optionally substituted aryl or an optionally substituted heteroaryl. n is an integer from 0 to 4, preferably an integer from 0 to 3, and more preferably 0 or 1.

The "aryl" in "optionally substituted aryl" includes, for example, aryl having 6 to 30 carbon atoms, preferably aryl having 6 to 24 carbon atoms, more preferably aryl having 6 to 20 carbon atoms, and even more preferably aryl having 6 to 12 carbon atoms.

Specific examples of "aryl" include monocyclic aryl phenyl, bicyclic aryl (2-, 3-, 4-) biphenylyl, condensed bicyclic aryl (1-, 2-) naphthyl, tricyclic aryl terphenylyl (m-terphenyl-2'-yl, m-terphenyl-4'-yl, m-terphenyl-5'-yl, o-terphenyl-3'-yl, o-terphenyl-4'-yl, p-terphenyl-2'-yl, m-terphenyl-2-yl, m-terphenyl-3-yl, m-terphenyl-4-yl, o-terphenyl-2-yl, o-terphenyl-3-yl, o-terphenyl-4-yl, p-terphenyl-2-yl, p-terphenyl-3-yl, p-terphenyl-4-yl), condensed tricyclic aryl Examples of the aryl include acenaphthylene-(1-,3-,4-,5-)yl, fluorene-(1-,2-,3-,4-,9-)yl, phenalene-(1-,2-)yl, and (1-,2-,3-,4-,9-)phenanthryl; the tetracyclic aryl is quaterphenylyl (5'-phenyl-m-terphenyl-2-yl, 5'-phenyl-m-terphenyl-3-yl, 5'-phenyl-m-terphenyl-4-yl, and m-quaterphenylyl); the condensed tetracyclic aryl is triphenylene-(1-,2-)yl, pyrene-(1-,2-,4-)yl, and naphthacene-(1-,2-,5-)yl; and the condensed pentacyclic aryl is perylene-(1-,2-,3-)yl and pentacene-(1-,2-,5-,6-)yl.

Examples of the "heteroaryl" in "optionally substituted heteroaryl" include heteroaryls having 2 to 30 carbon atoms, preferably heteroaryls having 2 to 25 carbon atoms, more preferably heteroaryls having 2 to 20 carbon atoms, even more preferably heteroaryls having 2 to 15 carbon atoms, and particularly preferably heteroaryls having 2 to 10 carbon atoms. Examples of heteroaryls include heterocycles containing, in addition to carbon, 1 to 5 heteroatoms selected from oxygen, sulfur, and nitrogen as ring-constituting atoms.

Specific examples of heteroaryl include furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, oxadiazolyl, furazanyl, thiadiazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, benzofuranyl, isobenzofuranyl, benzo[b]thienyl, indolyl, isoindolyl, 1H-indazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, 1H-benzotriazolyl, quinolyl, isoquinolyl, cinnolyl, quinazolyl, quinoxalinyl, phthalazinyl, naphthyridinyl, purinyl, pteridinyl, carbazolyl, acridinyl, phenoxazinyl, phenothiazinyl, phenazinyl, phenoxathiinyl, thianthrenyl, and indolizinyl.

In addition, the above aryl and heteroaryl may be substituted, for example, by the above aryl and heteroaryl, respectively.

The carbazole derivative may be a polymer in which a plurality of compounds represented by the above formula (ETM-9) are bonded together by single bonds or the like. In this case, in addition to single bonds, they may be bonded together by aryl rings (preferably polyvalent benzene rings, naphthalene rings, anthracene rings, fluorene rings, benzofluorene rings, phenalene rings, phenanthrene rings, or triphenylene rings).

Specific examples of the carbazole derivative include the following compounds.

This carbazole derivative can be produced using known raw materials and known synthesis methods.

<Triazine derivatives>
The triazine derivative is, for example, a compound represented by the following formula (ETM-10), preferably a compound represented by the following formula (ETM-10-1), the details of which are described in U.S. Patent Publication No. 2011/0156013.

Each Ar is independently an optionally substituted aryl or an optionally substituted heteroaryl. n is an integer from 1 to 3, preferably 2 or 3.

The "aryl" in "optionally substituted aryl" includes, for example, aryl having 6 to 30 carbon atoms, preferably aryl having 6 to 24 carbon atoms, more preferably aryl having 6 to 20 carbon atoms, and even more preferably aryl having 6 to 12 carbon atoms.

Specific examples of "aryl" include monocyclic aryl phenyl, bicyclic aryl (2-, 3-, 4-) biphenylyl, condensed bicyclic aryl (1-, 2-) naphthyl, tricyclic aryl terphenylyl (m-terphenyl-2'-yl, m-terphenyl-4'-yl, m-terphenyl-5'-yl, o-terphenyl-3'-yl, o-terphenyl-4'-yl, p-terphenyl-2'-yl, m-terphenyl-2-yl, m-terphenyl-3-yl, m-terphenyl-4-yl, o-terphenyl-2-yl, o-terphenyl-3-yl, o-terphenyl-4-yl, p-terphenyl-2-yl, p-terphenyl-3-yl, p-terphenyl-4-yl), condensed tricyclic aryl Examples of the aryl include acenaphthylene-(1-,3-,4-,5-)yl, fluorene-(1-,2-,3-,4-,9-)yl, phenalene-(1-,2-)yl, and (1-,2-,3-,4-,9-)phenanthryl; the tetracyclic aryl is quaterphenylyl (5'-phenyl-m-terphenyl-2-yl, 5'-phenyl-m-terphenyl-3-yl, 5'-phenyl-m-terphenyl-4-yl, and m-quaterphenylyl); the condensed tetracyclic aryl is triphenylene-(1-,2-)yl, pyrene-(1-,2-,4-)yl, and naphthacene-(1-,2-,5-)yl; and the condensed pentacyclic aryl is perylene-(1-,2-,3-)yl and pentacene-(1-,2-,5-,6-)yl.

Examples of the "heteroaryl" in "optionally substituted heteroaryl" include heteroaryls having 2 to 30 carbon atoms, preferably heteroaryls having 2 to 25 carbon atoms, more preferably heteroaryls having 2 to 20 carbon atoms, even more preferably heteroaryls having 2 to 15 carbon atoms, and particularly preferably heteroaryls having 2 to 10 carbon atoms. Examples of heteroaryls include heterocycles containing, in addition to carbon, 1 to 5 heteroatoms selected from oxygen, sulfur, and nitrogen as ring-constituting atoms.

Specific examples of heteroaryl include furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, oxadiazolyl, furazanyl, thiadiazolyl, triazolyl, tetrazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, benzofuranyl, isobenzofuranyl, benzo[b]thienyl, indolyl, isoindolyl, 1H-indazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, 1H-benzotriazolyl, quinolyl, isoquinolyl, cinnolyl, quinazolyl, quinoxalinyl, phthalazinyl, naphthyridinyl, purinyl, pteridinyl, carbazolyl, acridinyl, phenoxazinyl, phenothiazinyl, phenazinyl, phenoxathiinyl, thianthrenyl, and indolizinyl.

In addition, the above aryl and heteroaryl may be substituted, for example, by the above aryl and heteroaryl, respectively.

Specific examples of the triazine derivative include the following compounds:

This triazine derivative can be produced using known raw materials and known synthesis methods.

<Benzimidazole Derivatives>
The benzimidazole derivative is, for example, a compound represented by the following formula (ETM-11).

φ is an n-valent aryl ring (preferably an n-valent benzene ring, naphthalene ring, anthracene ring, fluorene ring, benzofluorene ring, phenalene ring, phenanthrene ring, or triphenylene ring), n is an integer from 1 to 4, and the "benzoimidazole-based substituent" is a substituent in which the pyridyl group in the "pyridine-based substituent" in the above formulae (ETM-2), (ETM-2-1), and (ETM-2-2) is replaced with a benzimidazole group, and at least one hydrogen in the benzimidazole derivative may be replaced with deuterium.

R ¹¹ in the benzimidazole group is hydrogen, alkyl having 1 to 24 carbon atoms, cycloalkyl having 3 to 12 carbon atoms, or aryl having 6 to 30 carbon atoms, and the explanation of R ¹¹ in the above formulae (ETM-2-1) and (ETM-2-2) can be cited.

It is further preferred that φ is an anthracene ring or a fluorene ring, and in this case, the structure can be explained with reference to the above formula (ETM-2-1) or formula (ETM-2-2), and R ¹¹ to R ¹⁸ in each formula can be explained with reference to the above formula (ETM-2-1) or formula (ETM-2-2). In addition, in the above formula (ETM-2-1) or formula (ETM-2-2), two pyridine-based substituents are explained as being bonded together, but when these are replaced with benzimidazole-based substituents, both pyridine-based substituents may be replaced with benzimidazole-based substituents (i.e., n=2), or one of the pyridine-based substituents may be replaced with a benzimidazole-based substituent and the other pyridine-based substituent may be replaced with R ¹¹ to R ¹⁸ (i.e., n=1). Furthermore, for example, at least one of R ¹¹ to R ¹⁸ in the above formula (ETM-2-1) may be replaced with a benzimidazole-based substituent, and the "pyridine-based substituent" may be replaced with R ¹¹ to R ¹⁸ .

Specific examples of the benzimidazole derivative include 1-phenyl-2-(4-(10-phenylanthracen-9-yl)phenyl)-1H-benzo[d]imidazole, 2-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole, 2-(3-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole, and 5-(10-(naphthalen-2-yl)anthracen-9-yl)-1,2-diphenyl-1H-benzo[d]imidazole. , 1-(4-(10-(naphthalene-2-yl)anthracen-9-yl)phenyl)-2-phenyl-1H-benzo[d]imidazole, 2-(4-(9,10-di(naphthalene-2-yl)anthracen-2-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole, 1-(4-(9,10-di(naphthalene-2-yl)anthracen-2-yl)phenyl)-2-phenyl-1H-benzo[d]imidazole, 5-(9,10-di(naphthalene-2-yl)anthracen-2-yl)-1,2-diphenyl-1H-benzo[d]imidazole, and the like.

This benzimidazole derivative can be produced using known raw materials and known synthesis methods.

<Phenanthroline Derivatives>
The phenanthroline derivative is, for example, a compound represented by the following formula (ETM-12) or formula (ETM-12-1), the details of which are described in WO 2006/021982.

φ is an n-valent aryl ring (preferably an n-valent benzene ring, naphthalene ring, anthracene ring, fluorene ring, benzofluorene ring, phenalene ring, phenanthrene ring or triphenylene ring), and n is an integer from 1 to 4.

R ¹¹ to R ¹⁸ in each formula are each independently hydrogen, alkyl (preferably alkyl having 1 to 24 carbon atoms), cycloalkyl (preferably cycloalkyl having 3 to 12 carbon atoms), or aryl (preferably aryl having 6 to 30 carbon atoms). In addition, in the above formula (ETM-12-1), any of R ¹¹ to R ¹⁸ is bonded to φ which is an aryl ring.

At least one hydrogen in each phenanthroline derivative may be replaced with deuterium.

The alkyl, cycloalkyl and aryl in R ¹¹ to R ¹⁸ can be the same as those described for R ¹¹ to R ¹⁸ in formula (ETM-2). In addition to the above examples, φ can have the following structural formula: In the structural formula, each R is independently hydrogen, methyl, ethyl, isopropyl, cyclohexyl, phenyl, 1-naphthyl, 2-naphthyl, biphenylyl or terphenylyl.

Specific examples of the phenanthroline derivative include 4,7-diphenyl-1,10-phenanthroline, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, 9,10-di(1,10-phenanthroline-2-yl)anthracene, 2,6-di(1,10-phenanthroline-5-yl)pyridine, 1,3,5-tri(1,10-phenanthroline-5-yl)benzene, 9,9'-difluoro-bi(1,10-phenanthroline-5-yl), bathocuproine, 1,3-bis(2-phenyl-1,10-phenanthroline-9-yl)benzene, and compounds represented by the following structural formulas.

This phenanthroline derivative can be produced using known raw materials and known synthesis methods.

式中、Ｒ^１～Ｒ^６は、それぞれ独立して、水素、フッ素、アルキル、シクロアルキル、アラルキル、アルケニル、シアノ、アルコキシまたはアリールであり、ＭはＬｉ、Ａｌ、Ｇａ、ＢｅまたはＺｎであり、ｎは１～３の整数である。 <Quinolinol metal complexes>
The quinolinol metal complex is, for example, a compound represented by the following general formula (ETM-13).

In the formula, R ¹ to R ⁶ are each independently hydrogen, fluorine, alkyl, cycloalkyl, aralkyl, alkenyl, cyano, alkoxy or aryl; M is Li, Al, Ga, Be or Zn; and n is an integer of 1 to 3.

Specific examples of quinolinol-based metal complexes include 8-quinolinol lithium, tris(8-quinolinolato)aluminum, tris(4-methyl-8-quinolinolato)aluminum, tris(5-methyl-8-quinolinolato)aluminum, tris(3,4-dimethyl-8-quinolinolato)aluminum, tris(4,5-dimethyl-8-quinolinolato)aluminum, tris(4,6-dimethyl-8-quinolinolato)aluminum, and bis( 2-methyl-8-quinolinolate)(phenolate)aluminum, bis(2-methyl-8-quinolinolate)(2-methylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(3-methylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(4-methylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(2-phenylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(phenolate)aluminum linolinate)(3-phenylphenolate)aluminum, bis(2-methyl-8-quinolinate)(4-phenylphenolate)aluminum, bis(2-methyl-8-quinolinate)(2,3-dimethylphenolate)aluminum, bis(2-methyl-8-quinolinate)(2,6-dimethylphenolate)aluminum, bis(2-methyl-8-quinolinate)(3,4-dimethylphenolate)aluminum, bis(2-methyl bis(2-methyl-8-quinolinolate)(3,5-dimethylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(3,5-di-t-butylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(2,6-diphenylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(2,4,6-triphenylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(2,4,6-trimethylphenolate)aluminum bis(2-methyl-8-quinolinolate)(2,4,5,6-tetramethylphenolate)aluminum, bis(2-methyl-8-quinolinolate)(1-naphtholate)aluminum, bis(2-methyl-8-quinolinolate)(2-naphtholate)aluminum, bis(2,4-dimethyl-8-quinolinolate)(2-phenylphenolate)aluminum, bis(2,4-dimethyl-8-quinolinolate)(3-phenylphenolate)aluminum bis(2,4-dimethyl-8-quinolinolate)(4-phenylphenolate)aluminum, bis(2,4-dimethyl-8-quinolinolate)(3,5-dimethylphenolate)aluminum, bis(2,4-dimethyl-8-quinolinolate)(3,5-di-t-butylphenolate)aluminum, bis(2-methyl-8-quinolinolate)aluminum-μ-oxo-bis(2-methyl-8-quinolinolate)aluminum quinolinolate)aluminum, bis(2,4-dimethyl-8-quinolinolate)aluminum-μ-oxo-bis(2,4-dimethyl-8-quinolinolate)aluminum, bis(2-methyl-4-ethyl-8-quinolinolate)aluminum-μ-oxo-bis(2-methyl-4-ethyl-8-quinolinolate)aluminum, bis(2-methyl-4-methoxy-8-quinolinolate)aluminum-μ-oxo-bis(2-methyl-4-methoxy-8-quinolinolate)aluminum quinolinolate)aluminum, bis(2-methyl-5-cyano-8-quinolinolate)aluminum-μ-oxo-bis(2-methyl-5-cyano-8-quinolinolate)aluminum, bis(2-methyl-5-trifluoromethyl-8-quinolinolate)aluminum-μ-oxo-bis(2-methyl-5-trifluoromethyl-8-quinolinolate)aluminum, and bis(10-hydroxybenzo[h]quinoline)beryllium.

This quinolinol-based metal complex can be produced using known raw materials and known synthesis methods.

ベンゾチアゾール誘導体は、例えば下記式（ＥＴＭ－１４－２）で表される化合物である。

<Thiazole Derivatives and Benzothiazole Derivatives>
The thiazole derivative is, for example, a compound represented by the following formula (ETM-14-1).

The benzothiazole derivative is, for example, a compound represented by the following formula (ETM-14-2).

In each formula, φ is an n-valent aryl ring (preferably an n-valent benzene ring, naphthalene ring, anthracene ring, fluorene ring, benzofluorene ring, phenalene ring, phenanthrene ring, or triphenylene ring), and n is an integer from 1 to 4. A "thiazole-based substituent" or a "benzothiazole-based substituent" is a substituent in which the pyridyl group in the "pyridine-based substituent" in the above formulae (ETM-2), (ETM-2-1), and (ETM-2-2) is replaced with a thiazole group or a benzothiazole group described below, and at least one hydrogen atom in the thiazole derivative and the benzothiazole derivative may be replaced with a deuterium atom.

It is further preferred that φ is an anthracene ring or a fluorene ring, and in this case, the structure can be explained with reference to the above formula (ETM-2-1) or formula (ETM-2-2), and R ¹¹ to R ¹⁸ in each formula can be explained with reference to the above formula (ETM-2-1) or formula (ETM-2-2). In addition, in the above formula (ETM-2-1) or formula (ETM-2-2), two pyridine-based substituents are explained as being bonded together, but when these are replaced with a thiazole-based substituent (or a benzothiazole-based substituent), both pyridine-based substituents may be replaced with a thiazole-based substituent (or a benzothiazole-based substituent) (i.e., n=2), or one of the pyridine-based substituents may be replaced with a thiazole-based substituent (or a benzothiazole-based substituent) and the other pyridine-based substituent may be replaced with R ¹¹ to R ¹⁸ (i.e., n=1). Furthermore, for example, at least one of R ¹¹ to R ¹⁸ in the above formula (ETM-2-1) may be replaced with a thiazole-based substituent (or a benzothiazole-based substituent) to replace the "pyridine-based substituent" with R ¹¹ to R ¹⁸ .

These thiazole or benzothiazole derivatives can be produced using known raw materials and known synthesis methods.

The electron transport layer or the electron injection layer may further contain a substance capable of reducing the material forming the electron transport layer or the electron injection layer. As the reducing substance, various substances can be used as long as they have a certain degree of reducing ability. For example, at least one selected from the group consisting of alkali metals, alkaline earth metals, rare earth metals, oxides of alkali metals, halides of alkali metals, oxides of alkaline earth metals, halides of alkaline earth metals, oxides of rare earth metals, halides of rare earth metals, organic complexes of alkali metals, organic complexes of alkaline earth metals, and organic complexes of rare earth metals can be suitably used.

Preferred reducing substances include alkali metals such as Na (work function 2.36 eV), K (2.28 eV), Rb (2.16 eV), or Cs (1.95 eV), and alkaline earth metals such as Ca (2.9 eV), Sr (2.0-2.5 eV), or Ba (2.52 eV), with substances with a work function of 2.9 eV or less being particularly preferred. Of these, more preferred reducing substances are alkali metals such as K, Rb, or Cs, more preferably Rb or Cs, and most preferably Cs. These alkali metals have particularly high reducing ability, and by adding a relatively small amount to the material forming the electron transport layer or electron injection layer, the luminance of the organic EL element can be improved and the lifespan can be extended. Furthermore, as a reducing substance having a work function of 2.9 eV or less, a combination of two or more of these alkali metals is also preferred, and in particular, a combination containing Cs is preferred, for example, a combination of Cs and Na, Cs and K, Cs and Rb, or a combination of Cs, Na and K. By containing Cs, the reducing ability can be efficiently exhibited, and by adding it to a material forming an electron transport layer or an electron injection layer, the luminance of the organic EL element can be improved and the life can be extended.

<Cathode in Organic Electroluminescent Device>
The cathode 108 serves to inject electrons into the light-emitting layer 105 via the electron injection layer 107 and the electron transport layer 106 .

The material for forming the cathode 108 is not particularly limited as long as it is a material that can efficiently inject electrons into the organic layer, but the same material as the material for forming the anode 102 can be used. Among them, metals such as tin, indium, calcium, aluminum, silver, copper, nickel, chromium, gold, platinum, iron, zinc, lithium, sodium, potassium, cesium, and magnesium, or alloys thereof (magnesium-silver alloy, magnesium-indium alloy, aluminum-lithium alloy such as lithium fluoride/aluminum, etc.), etc. are preferred. In order to increase the electron injection efficiency and improve the device characteristics, lithium, sodium, potassium, cesium, calcium, magnesium, or alloys containing these low work function metals are effective. However, these low work function metals are generally unstable in the air. To improve this point, for example, a method is known in which a trace amount of lithium, cesium, or magnesium is doped into the organic layer to use a highly stable electrode. Other dopants that can be used include inorganic salts such as lithium fluoride, cesium fluoride, lithium oxide, and cesium oxide. However, they are not limited to these.

In addition, preferred examples of electrode protection include lamination of metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or alloys using these metals, as well as inorganic materials such as silica, titania, and silicon nitride, polyvinyl alcohol, vinyl chloride, and hydrocarbon polymer compounds. There are no particular limitations on the method of producing these electrodes, and they can be produced by resistance heating, electron beam deposition, sputtering, ion plating, coating, and other methods as long as they can provide electrical conductivity.

<Binder that may be used in each layer>
The materials used for the hole injection layer, hole transport layer, light emitting layer, electron transport layer and electron injection layer can form each layer alone, but they can also be used as a polymer binder by dispersing them in a solvent-soluble resin such as polyvinyl chloride, polycarbonate, polystyrene, poly(N-vinylcarbazole), polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, vinyl acetate resin, ABS resin, polyurethane resin, or a curable resin such as phenol resin, xylene resin, petroleum resin, urea resin, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, silicone resin, or the like.

<Method for Producing Organic Electroluminescent Device>
Each layer constituting an organic EL element can be formed by forming the material to be formed into a thin film by a method such as vapor deposition, resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination, printing, spin coating or casting, coating, etc. The thickness of each layer thus formed is not particularly limited and can be set appropriately according to the properties of the material, but is usually in the range of 2 nm to 5000 nm. The thickness can usually be measured with a quartz crystal oscillation type film thickness measuring device, etc. When forming a thin film by vapor deposition, the vapor deposition conditions vary depending on the type of material, the intended crystal structure and association structure of the film, etc. The vapor deposition conditions are generally preferably set appropriately in the range of boat heating temperature +50 to +400°C, vacuum degree 10 ^-6 to 10 ^-3 Pa, vapor deposition rate 0.01 to 50 nm/sec, substrate temperature -150 to +300°C, and film thickness 2 nm to 5 μm.

Next, as an example of a method for producing an organic EL element, a method for producing an organic EL element consisting of an anode, a hole injection layer, a hole transport layer, a light-emitting layer consisting of a host material and a dopant material, an electron transport layer, an electron injection layer, and a cathode will be described. After forming a thin film of an anode material on a suitable substrate by a deposition method or the like to produce an anode, a thin film of a hole injection layer and a hole transport layer is formed on the anode. A host material and a dopant material are co-deposited on the anode to form a thin film to produce a light-emitting layer, an electron transport layer and an electron injection layer are formed on the light-emitting layer, and a thin film of a cathode material is further formed by a deposition method or the like to produce a cathode, thereby obtaining the desired organic EL element. In addition, in the production of the above-mentioned organic EL element, it is also possible to reverse the production order and produce the cathode, electron injection layer, electron transport layer, light-emitting layer, hole transport layer, hole injection layer, and anode in that order.

When applying a DC voltage to the organic EL element obtained in this way, the anode should be set to + and the cathode to -. When a voltage of about 2 to 40 V is applied, light emission can be observed from the transparent or semi-transparent electrode side (anode or cathode, or both). This organic EL element also emits light when a pulsed current or AC current is applied. The waveform of the applied AC can be any waveform.

<Application examples of organic electroluminescent devices>
The present invention can also be applied to a display device having an organic EL element or a lighting device having an organic EL element.
A display device or lighting device including an organic EL element can be manufactured by a known method, for example, by connecting the organic EL element according to this embodiment to a known driving device, and can be driven appropriately using a known driving method such as DC driving, pulse driving, or AC driving.

Examples of display devices include panel displays such as color flat panel displays, and flexible displays such as flexible color organic electroluminescent (EL) displays (see, for example, JP-A-10-335066, JP-A-2003-321546, JP-A-2004-281086, etc.). Display methods include, for example, matrix and/or segment methods. Note that matrix display and segment display may coexist in the same panel.

In a matrix, the pixels for display are arranged two-dimensionally, such as in a grid or mosaic pattern, and a collection of pixels displays characters and images. The shape and size of the pixels are determined by the application. For example, square pixels with sides of 300 μm or less are usually used to display images and characters on computers, monitors, and televisions, and pixels with sides on the order of mm are used for large displays such as display panels. For monochrome display, pixels of the same color can be arranged, but for color display, red, green, and blue pixels are displayed side by side. In this case, there are typically delta types and stripe types. The driving method for this matrix can be either line sequential driving method or active matrix. Line sequential driving has the advantage of being simpler in structure, but when considering operating characteristics, active matrix may be superior, so it is necessary to use it according to the application.

In the segment type, a pattern is formed to display predetermined information, and a specific area is illuminated. Examples include the time and temperature displays on digital clocks and thermometers, the operating status displays on audio equipment and induction cookers, and panel displays on automobiles.

Examples of lighting devices include lighting devices for indoor lighting, backlights for liquid crystal display devices, etc. (see, for example, JP 2003-257621 A, JP 2003-277741 A, JP 2004-119211 A, etc.). Backlights are mainly used for the purpose of improving the visibility of non-self-luminous display devices, and are used in liquid crystal display devices, clocks, audio devices, automobile panels, display boards, signs, etc. In particular, for backlights for liquid crystal display devices, especially for personal computers where thinning is an issue, considering that conventional methods are made up of fluorescent lamps and light guide plates and therefore difficult to make thin, the backlight using the light-emitting element according to this embodiment is characterized by its thinness and light weight.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. First, a synthesis example of a polycyclic aromatic compound will be described below.

Synthesis Example (1): Synthesis of Compound (1-101)

1,3-Dibromo-5-fluorobenzene (50.0 g), carbazole (36.2 g), potassium carbonate (54.0 g) and N-methylpyrrolidone (NMP, 250 mL) were placed in a flask under a nitrogen atmosphere and stirred at 170° C. for 6 hours. After the reaction, the reaction solution was cooled, water was added, and the precipitate was filtered. The precipitate was washed with water and methanol and dried, and then purified with a silica gel column (eluent: toluene/heptane = 2/8 (volume ratio)). The crude product was further dissolved in toluene and reprecipitated with heptane to obtain compound (A) (55.3 g).

Compound (A) (25.0 g), 3-(2-methylphenyl)phenol (25.2 g), copper iodide (0.60 g), iron tris(acetylacetonato) (2.20 g), potassium carbonate (34.0 g) and N-methylpyrrolidone (NMP, 100 mL) were placed in a flask under a nitrogen atmosphere and stirred at 150° C. for 3 hours. After the reaction, the reaction solution was cooled and NMP was distilled off under reduced pressure. Water and ethyl acetate were added to the residue and stirred, and then filtered through Celite (registered trademark). Ammonia water was added to the filtrate, and after stirring, the aqueous layer was removed. The organic layer was washed with water twice and then concentrated under reduced pressure. The obtained crude product was purified using a silica gel column (eluent: toluene/heptane = 3/7 (volume ratio)) to obtain compound (B) (28.1 g).

In a flask containing compound (B) (25.0 g) and xylene (140 ml), s-butyllithium/cyclohexane, n-hexane solution (1.05 M, 41.1 ml) was added under nitrogen atmosphere while cooling with an ice bath. After the dropwise addition, the temperature was raised to 70°C and stirred for 3 hours, and then low boiling point components were distilled off under reduced pressure. The mixture was cooled to -50°C and boron tribromide (12.4 g) was added, and the mixture was heated to room temperature and stirred for 0.5 hours. Then, the mixture was cooled again in an ice bath and N,N-diisopropylethylamine (10.6 g) was added. The mixture was stirred at room temperature until the heat generation subsided, then heated to 120°C and heated and stirred for 4 hours, and aluminum chloride (12.1 g) was added and heated and stirred for 2 hours. The reaction solution was cooled to room temperature, and an aqueous sodium acetate solution cooled in an ice bath was added, followed by ethyl acetate, and stirred for 1 hour, causing a precipitate to precipitate, so heptane was added and the precipitate was filtered. Next, the precipitate was purified using a silica gel short column (eluent: toluene), further dissolved in toluene, and then reprecipitated with heptane, and finally purified by sublimation to obtain compound (1-101) (16.0 g).

The structure of the obtained compound was confirmed by NMR measurement.
¹ H NMR (δppm in CDCl ₃ ); 2.4 (s, 6H), 7.3-7.4 (m, 10H), 7.4 (m, 2H), 7.5 (m, 2H), 7.5 (s, 2H), 7.6 (d, 2H), 7.7 (d, 2H), 8.2 (d, 2H), 8.8 (d, 2H).

Synthesis Example (2): Synthesis of Compound (1-201)

1,3-Dibromo-5-fluorobenzene (80.0 g), 4-(9H-carbazol-9-yl)phenylboronic acid (130.9 g), dichlorobis[(di-t-butyl(4-dimethylaminophenyl)phosphino)palladium (Pd-132, 1.47 g) as a palladium catalyst, potassium phosphate (176 g), toluene (600 mL), isopropyl alcohol (IPA, 150 mL) and water (70 mL) were placed in a flask under a nitrogen atmosphere and stirred at reflux temperature for 2 hours. After cooling the reaction solution, water was added and stirred, toluene was added for liquid separation and extraction, the aqueous layer was removed, and the organic layer was further washed with water. The crude product obtained by concentrating the organic layer under reduced pressure was further washed with a mixed solution of heptane/ethyl acetate = 4/1 (volume ratio) to obtain compound (C) (166 g).

Compound (C) (25.0 g), 3-(2-methylphenyl)phenol (28.5 g), potassium carbonate (39.0 g) and NMP (150 mL) were placed in a flask under a nitrogen atmosphere and stirred at 200° C. for 2 hours, after which potassium phosphate (37 g) was added and the mixture was stirred at 200° C. for another 4 hours. After cooling the reaction solution, NMP was distilled off under reduced pressure, toluene and water were added and stirred, and the aqueous layer was removed. The organic layer was further washed twice with water and then concentrated under reduced pressure. The obtained crude product was purified using a silica gel column (eluent: toluene/heptane = 3/7 (volume ratio), then changed to 4/6 (volume ratio)) to obtain compound (D) (40 g).

In a flask containing compound (D) (39.0 g) and xylene (190 ml), s-butyllithium/cyclohexane, n-hexane solution (1.05 M, 57.0 ml) was added under a nitrogen atmosphere while cooling with an ice bath. After the dropwise addition was completed, the temperature was raised to 70°C and stirred for 3 hours, and then low boiling point components were distilled off under reduced pressure. The mixture was cooled to -50°C and boron tribromide (17.1 g) was added, and the mixture was heated to room temperature and stirred for 0.5 hours. Then, the mixture was cooled again in an ice bath and N,N-diisopropylethylamine (14.7 g) was added. The mixture was stirred at room temperature until the heat generation subsided, and then heated to 130°C and heated and stirred for 4 hours. The reaction solution was cooled to room temperature, and an aqueous sodium acetate solution cooled in an ice bath was added, followed by ethyl acetate, and the mixture was stirred for 1 hour, resulting in the precipitation of a precipitate, which was then filtered after further addition of heptane. The precipitate was washed with methanol, water, ethyl acetate, and heptane in this order, and the solid was then dried, suspended in ethyl acetate, washed by reflux, dissolved in hot chlorobenzene, concentrated and reprecipitated, and finally purified by sublimation to obtain compound (1-201) (27.0 g).

The structure of the obtained compound was confirmed by NMR measurement.
¹ H NMR (δppm in CDCl ₃ ); 2.4 (s, 6H), 7.3-7.4 (m, 8H), 7.4 (m, 4H), 7.4-7.5 (m, 2H), 7.5 (d, 2H), 7.6 (d, 2H), 7.6 (s, 2H), 7.7 (d, 2H), 8.0 (d, 2H) , 8.2 (d, 2H), 8.8 (d, 2H).

By appropriately changing the raw material compounds, other polycyclic aromatic compounds of the present invention can be synthesized in a manner similar to the synthesis examples described above.

Next, in order to explain the present invention in more detail, examples of organic EL elements using the compounds of the present invention are shown, but the present invention is not limited to these.

<Evaluation of Organic EL Device>
Organic EL elements according to Examples 1 and 2 and Comparative Examples 1 and 2 were prepared, and the voltage (V) and external quantum efficiency (%), which are characteristics at 1000 cd/ ^m2 emission, were measured. Next, the time during which the luminance was maintained at 90% or more of the initial luminance when driven at a constant current density of 10 mA/ ^cm2 , was measured.

The quantum efficiency of a light-emitting element can be classified into internal quantum efficiency and external quantum efficiency. The internal quantum efficiency indicates the proportion of external energy injected as electrons (or holes) into the light-emitting layer of the light-emitting element that is converted purely into photons. On the other hand, the external quantum efficiency is calculated based on the amount of these photons that are emitted to the outside of the light-emitting element. Since some of the photons generated in the light-emitting layer are absorbed or continue to be reflected inside the light-emitting element and are not emitted to the outside of the light-emitting element, the external quantum efficiency is lower than the internal quantum efficiency.

The method for measuring the external quantum efficiency is as follows. Using an Advantest voltage/current generator R6144, a voltage was applied so that the luminance of the element was 1000 cd/ ^m2 , and the element was made to emit light. Using a TOPCON spectroradiometer SR-3AR, the spectral radiance of the visible light region was measured from a direction perpendicular to the light-emitting surface. Assuming that the light-emitting surface is a completely diffusing surface, the measured spectral radiance value of each wavelength component was divided by the wavelength energy and multiplied by π to obtain the number of photons at each wavelength. Next, the number of photons was integrated over the entire wavelength range observed to obtain the total number of photons emitted from the element. The value obtained by dividing the applied current value by the elementary charge was taken as the number of carriers injected into the element, and the value obtained by dividing the total number of photons emitted from the element by the number of carriers injected into the element was taken as the external quantum efficiency.

The material configurations of the layers in the fabricated organic EL elements according to Examples 1 and 2 and Comparative Examples 1 and 2, and the EL characteristic data are shown in Table 1 below.

In the above Table 1, "HI" is N ⁴ ,N ^{4 '} -diphenyl-N ⁴ ,N ^{4 '} -bis(9-phenyl-9H-carbazol-3-yl)-[1,1'-biphenyl]-4,4'-diamine, "IL" is 1,4,5,8,9,12-hexaazatriphenylene hexacarbonitrile, "HT-1" is N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine, "HT-2" is N,N-bis(4-(dibenzo[b,d]furan-4-yl)phenyl)-[1,1':4',1"-terphenyl]-4-amine, and "BH-1" is 2-(10- "BD-1" is 2,12-di-t-butyl-5,9-bis(4-(t-butyl)phenyl)-7-methyl-5,9-dihydro-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene, comparative compound (1) is 9-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene-7-yl)-9H-carbazole, and comparative compound (2) is 9-(4-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene-7-yl)phenyl)-9H-carbazole. The chemical structures of "Liq" and "BD-2" are shown below.

Example 1
<Device in which the electron transport material is compound (1-101)>
A 26 mm × 28 mm × 0.7 mm glass substrate (manufactured by Optoscience Co., Ltd.) on which an ITO film having a thickness of 180 nm was formed by sputtering and polished to 150 nm was used as a transparent support substrate. This transparent support substrate was fixed to a substrate holder of a commercially available deposition apparatus (manufactured by Choshu Sangyo Co., Ltd.), and a tantalum deposition boat containing HI, IL, HT-1, HT-2, BH-1, BD-1, and compound (1-101), and an aluminum nitride deposition boat containing Liq, Mg, and Ag were attached.

The following layers were formed in sequence on the ITO film of the transparent support substrate. The vacuum chamber was depressurized to 5×10 ⁻⁴ Pa, and first, HI was heated and evaporated to a thickness of 40 nm, then IL was heated and evaporated to a thickness of 5 nm, then HT-1 was heated and evaporated to a thickness of 15 nm, and then HT-2 was heated and evaporated to a thickness of 10 nm to form a hole layer consisting of four layers. Next, BH-1 and BD-1 were heated simultaneously and evaporated to a thickness of 25 nm to form a light-emitting layer. The evaporation rate was adjusted so that the weight ratio of BH-1 to BD-1 was approximately 98:2. Furthermore, compound (1-101) and Liq were heated simultaneously and evaporated to a thickness of 5 nm to form an electron transport layer. The evaporation rate was adjusted so that the weight ratio of compound (1-101) to Liq was approximately 50:50. The evaporation rate of each layer was 0.01 to 1 nm/sec. Then, Liq was heated and evaporated at a deposition rate of 0.01 to 0.1 nm/sec to a thickness of 1 nm, and then magnesium and silver were simultaneously heated and evaporated to a thickness of 100 nm to form a cathode, thereby obtaining an organic EL device. At this time, the deposition rate was adjusted between 0.1 nm and 10 nm/sec so that the atomic ratio of magnesium to silver was 10:1.

A direct current voltage was applied to the ITO electrode as the anode and the magnesium/silver electrode as the cathode, and the characteristics at 1000 cd/ ^m2 of light emission were measured, resulting in blue light emission. The driving voltage was 4.1 V, the external quantum efficiency was 6.1%, and the element lifetime was 362 hours.

Example 2
<Device in which the electron transport material is compound (1-201)>
An organic EL device was obtained in the same manner as in Example 1, except that the material of the electron transport layer was changed to compound (1-201). When the characteristics were measured at 1000 cd/ ^m2 , blue light was emitted. In addition, the driving voltage was 3.5 V, the external quantum efficiency was 6.3%, and the device lifetime was 332 hours.

<Comparative Example 1>
<Device in which the electron transport material is the comparative compound (1)>
An organic EL device was obtained in the same manner as in Example 1, except that the material of the electron transport layer was changed to the comparative compound (1). When the characteristics were measured at 1000 cd/ ^m2 , blue light was emitted. In addition, the driving voltage was 3.7 V, the external quantum efficiency was 5.7%, and the device life was 85 hours.

<Comparative Example 2>
<Device in which the electron transport material is the comparative compound (2)>
An organic EL device was obtained in the same manner as in Example 1, except that the material of the electron transport layer was changed to the comparative compound (2). When the characteristics were measured at 1000 cd/ ^m2 , blue light was emitted. In addition, the driving voltage was 3.4 V, the external quantum efficiency was 5.8%, and the device life was 93 hours.

According to a preferred embodiment of the present invention, an organic EL element is produced using an electron transport material containing a polycyclic aromatic compound represented by general formula (1), thereby providing an organic EL element having excellent luminous efficiency and element life, particularly excellent element life.

REFERENCE SIGNS LIST 100 Organic electroluminescent element 101 Substrate 102 Anode 103 Hole injection layer 104 Hole transport layer 105 Light-emitting layer 106 Electron transport layer 107 Electron injection layer 108 Cathode

Claims (17)

An electron transport material or electron injection material comprising a polycyclic aromatic compound represented by the following general formula (1) or a polymer of a polycyclic aromatic compound having a plurality of unit structures represented by the following general formula (1):

(In the above formula (1),
ring A, ring B and ring C are each independently an aryl ring or a heteroaryl ring, and at least one hydrogen atom in these rings may be substituted;
provided that at least one of the rings A, B and C is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on at least one of the rings A, B and C via a phenylene group;
^Y1 is B, P, P=O, or P=S ;
X ¹ and X ² are each independently >O, >N-R, >C(-R) ₂ , >S or >Se, R of the >N-R is an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted alkyl or an optionally substituted cycloalkyl, R of the >C(-R) ₂ is hydrogen, an optionally substituted aryl, an optionally substituted alkyl or an optionally substituted cycloalkyl, R of the >N-R and/or R of the >C(-R) ₂ may be bonded to at least one of the A ring, the B ring and the C ring by -O-, -S-, -C(-R) ₂ - or a single bond, R of the -C(-R) ₂ - is hydrogen, an alkyl or a cycloalkyl,
At least one hydrogen atom in the compound or unit structure represented by formula (1) may be substituted with deuterium, cyano or halogen, and
At least one of the ring A, ring B and ring C has a group represented by the general formula (oR) bonded at *;
In the above formula (oR), R ²¹ is alkyl, R ²² to R ²⁵ are each independently hydrogen, aryl, heteroaryl, alkyl or cycloalkyl, adjacent groups among R ²² to R ²⁵ may be bonded to each other to form an aryl ring or heteroaryl ring together with the benzene ring, and at least one hydrogen atom in the formed ring may be substituted with an aryl, heteroaryl, alkyl or cycloalkyl. In the above formula (1),
ring A, ring B and ring C are each independently an aryl ring or a heteroaryl ring, at least one hydrogen atom in these rings may be replaced by a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl , a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted alkoxy or a substituted or unsubstituted aryloxy, and these rings have a 5- or 6-membered ring that shares a bond with the central fused bicyclic structure of the above formula composed of Y ¹ , X ¹ and X ² ,
provided that at least one of the rings A, B and C is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on at least one of the rings A, B and C via a phenylene group;
^Y1 is B, P, P=O, or P=S ;
X ¹ and X ² are each independently >O, >N-R, >C(-R) ₂ , >S or >Se, R of the >N-R is aryl which may be substituted with alkyl or cycloalkyl, heteroaryl which may be substituted with alkyl or cycloalkyl, alkyl or cycloalkyl, R of the >C(-R) ₂ is hydrogen, aryl which may be substituted with alkyl or cycloalkyl, alkyl or cycloalkyl, R of the >N-R and/or R of the >C(-R) ₂ may be bonded to at least one of the A ring, the B ring and the C ring by -O-, -S-, -C(-R) ₂ - or a single bond, R of the -C(-R) ₂ - is hydrogen, alkyl or cycloalkyl,
At least one hydrogen atom in the compound or unit structure represented by formula (1) may be substituted with deuterium, cyano or halogen.
In the case of a polymer, it is a dimer or trimer having two or three unit structures represented by general formula (1), and
At least one of the ring A, ring B and ring C has a group represented by the general formula (oR) bonded at *;
In the above formula (oR), R ²¹ is an alkyl having 1 to 24 carbon atoms, R ²² to R ²⁵ are each independently hydrogen, an aryl having 6 to 30 carbon atoms, a heteroaryl having 2 to 30 carbon atoms, an alkyl having 1 to 24 carbon atoms, or a cycloalkyl having 3 to 24 carbon atoms, adjacent groups among R ²² to R ²⁵ may be bonded to each other to form an aryl ring having 9 to 16 carbon atoms or a heteroaryl ring having 6 to 15 carbon atoms together with a benzene ring, and at least one hydrogen atom in the formed ring may be substituted with an aryl ring having 6 to 30 carbon atoms, a heteroaryl ring having 2 to 30 carbon atoms, an alkyl ring having 1 to 24 carbon atoms, or a cycloalkyl ring having 3 to 24 carbon atoms;
2. The electron transporting or injecting material according to claim 1. In the above formula (1),
The ring A is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on the ring A via a phenylene group;
a group represented by the above general formula (oR) is bonded to the ring B and/or ring C at *;
3. The electron transporting material or electron injecting material according to claim 1 or 2. The electron transport material or electron injection material according to any one of claims 1 to 3, wherein in the above formula (1), the halogen is fluorine. An electron transport material or electron injection material comprising a polycyclic aromatic compound represented by the following general formula (2) or a polymer of a polycyclic aromatic compound having a plurality of unit structures represented by the following general formula (2) :

(In the above formula (2),
R ¹ to R ¹¹ are each independently hydrogen, aryl, heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl, alkyl, cycloalkyl , alkoxy, or aryloxy, in which at least one hydrogen may be replaced by aryl, heteroaryl, alkyl, or cycloalkyl, or adjacent groups among R ¹ to R ¹¹ may be bonded to each other to form an aryl ring or heteroaryl ring together with ring a, ring b, or ring c, in which at least one hydrogen in the formed ring may be replaced by aryl, heteroaryl, diarylamino, diheteroarylamino, arylheteroarylamino, diarylboryl, alkyl, cycloalkyl , alkoxy, or aryloxy, in which at least one hydrogen may be replaced by aryl, heteroaryl, alkyl, or cycloalkyl,
provided that at least one of the ring a, ring b, ring c, and the aryl ring and heteroaryl ring formed together with these rings is substituted with a diphenylamino group, a carbazolyl group, or a benzocarbazolyl group which may be substituted with an alkyl having 1 to 4 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms, and these groups may be substituted via a phenylene group on at least one of the ring a, ring b, ring c, and the aryl ring and heteroaryl ring formed together with these rings;
^Y1 is B, P, P=O, or P=S ;
X ¹ and X ² are each independently >O, >N-R, >C(-R) ₂ , >S or >Se, R of the >N-R is an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, an alkyl having 1 to 6 carbon atoms or a cycloalkyl having 3 to 14 carbon atoms, R of the >C(-R) ₂ is hydrogen, an aryl having 6 to 12 carbon atoms, an alkyl having 1 to 6 carbon atoms or a cycloalkyl having 3 to 14 carbon atoms, R of the >N-R and/or R of the >C(-R) ₂ may be bonded to at least one of the ring a, ring b and ring c by -O-, -S-, -C(-R) ₂ - or a single bond, R of the -C(-R) ₂ - is an alkyl having 1 to 6 carbon atoms or a cycloalkyl having 3 to 14 carbon atoms,
At least one hydrogen atom in the compound or unit structure represented by formula (2) may be substituted with deuterium, cyano or halogen.
In the case of a polymer, it is a dimer or trimer having two or three unit structures represented by general formula (2), and
At least one of the ring a, ring b, ring c, and the aryl ring and heteroaryl ring formed together with these rings has a group represented by general formula (oR) bonded at *;
In the above formula (oR), R ²¹ is an alkyl having 1 to 12 carbon atoms, R ²² to R ²⁵ are each independently hydrogen, an aryl having 6 to 16 carbon atoms, a heteroaryl having 2 to 20 carbon atoms, an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms, and adjacent groups among R ²² to R ²⁵ may be bonded to each other to form a naphthalene ring, a phenanthrene ring, a fluorene ring, or a carbazole ring together with the benzene ring, and at least one hydrogen atom in the formed ring may be substituted with an aryl having 6 to 16 carbon atoms, a heteroaryl having 2 to 20 carbon atoms, an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms. In the above formula (2),
R ¹ to R ¹¹ are each independently hydrogen, an aryl having 6 to 30 carbon atoms (the aryl may be substituted with a heteroaryl having 2 to 15 carbon atoms), a heteroaryl having 2 to 30 carbon atoms, a diarylamino (wherein the aryl has 6 to 12 carbon atoms), a diarylboryl (wherein the aryl has 6 to 12 carbon atoms), an alkyl having 1 to 24 carbon atoms, or a cycloalkyl having ³ to 24 carbon atoms; adjacent groups among ¹¹ may be bonded to each other to form an aryl ring having 9 to 16 carbon atoms or a heteroaryl ring having 6 to 15 carbon atoms together with ring a, ring b or ring c, and at least one hydrogen atom in the formed ring may be substituted by an aryl having 6 to 30 carbon atoms (the aryl may be substituted by a heteroaryl having 2 to 15 carbon atoms), a heteroaryl having 2 to 30 carbon atoms, diarylamino (wherein the aryl is an aryl having 6 to 12 carbon atoms), diarylboryl (wherein the aryl is an aryl having 6 to 12 carbon atoms), an alkyl having 1 to 24 carbon atoms or a cycloalkyl having 3 to 24 carbon atoms;
provided that at least one of the ring a, ring b, ring c, and the aryl ring and heteroaryl ring formed together with these rings is substituted with a diphenylamino group, a carbazolyl group, or a benzocarbazolyl group which may be substituted with an alkyl having 1 to 4 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms, and these groups may be substituted via a phenylene group on at least one of the ring a, ring b, ring c, and the aryl ring and heteroaryl ring formed together with these rings;
^Y1 is B, P, P=O, or P=S ;
^X1 and ^X2 are each independently >O, >N-R, >C(-R) ₂ or >S, R of the >N-R is an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms, and R of the >C(-R) ₂ is a hydrogen atom, an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms or a cycloalkyl having 5 to 10 carbon atoms;
At least one hydrogen atom in the compound or unit structure represented by formula (2) may be substituted with deuterium, cyano or halogen.
In the case of a polymer, it is a dimer or trimer having two or three unit structures represented by general formula (2), and
At least one of the ring a, ring b, ring c, and the aryl ring and heteroaryl ring formed together with these rings has a group represented by general formula (oR) bonded at *;
In the above formula (oR), R ²¹ is an alkyl having 1 to 6 carbon atoms, R ²² to R ²⁵ are each independently a hydrogen atom, an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, an alkyl having 1 to 6 carbon atoms, or a cycloalkyl having 3 to 14 carbon atoms, adjacent groups among R ²² to R ²⁵ may be bonded to each other to form a naphthalene ring, a phenanthrene ring, a fluorene ring, or a carbazole ring together with a benzene ring, and at least one hydrogen atom in the formed ring may be substituted with an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, an alkyl having 1 to 6 carbon atoms, or a cycloalkyl having 3 to 14 carbon atoms;
The electron transporting or injecting material according to claim 5 . In the above formula (2),
R ¹ to R ¹¹ are each independently a hydrogen atom, an aryl having 6 to 16 carbon atoms (wherein the aryl may be substituted with a heteroaryl having 2 to 10 carbon atoms), a heteroaryl having 2 to 20 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 10 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 10 carbon atoms), an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms;
provided that at least one of the ring a, ring b and ring c is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on at least one of the ring a, ring b and ring c via a phenylene group;
^Y1 is B, P, P=O or P=S;
^X1 and ^X2 are each independently >O, >N-R, or >C(-R) ₂ , R of the >N-R is an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms, or a cycloalkyl having 5 to 10 carbon atoms, and R of the >C(-R) ₂ is a hydrogen atom, an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms, or a cycloalkyl having 5 to 10 carbon atoms;
In the case of a polymer, it is a dimer or trimer having two or three unit structures represented by general formula (2), and
At least one of the ring a, ring b and ring c has a group represented by general formula (oR) bonded at *;
In the above formula (oR), R ²¹ is an alkyl group having 1 to 4 carbon atoms, and R ²² to R ²⁵ are each independently a hydrogen atom, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms.
The electron transporting or injecting material according to claim 5 . In the above formula (2),
R ¹ to R ¹¹ are each independently a hydrogen atom, an aryl having 6 to 16 carbon atoms (wherein the aryl may be substituted with a heteroaryl having 2 to 10 carbon atoms), a heteroaryl having 2 to 20 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 10 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 10 carbon atoms), an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms;
provided that at least one of the ring a, ring b and ring c is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on at least one of the ring a, ring b and ring c via a phenylene group;
^Y1 is B or P=O;
^X1 and ^X2 each independently represent >O or >N-R, and R in the >N-R represents an aryl having 6 to 10 carbon atoms, an alkyl having 1 to 4 carbon atoms, or a cycloalkyl having 5 to 10 carbon atoms;
In the case of a polymer, it is a dimer or trimer having two or three unit structures represented by general formula (2), and
At least one of the ring a, ring b and ring c has a group represented by general formula (oR) bonded at *;
In the above formula (oR), R ²¹ is an alkyl group having 1 to 4 carbon atoms, and R ²² to R ²⁵ are each independently a hydrogen atom, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms.
The electron transporting or injecting material according to claim 5 . In the above formula (2),
R ¹ to R ¹¹ are each independently a hydrogen atom, an aryl having 6 to 16 carbon atoms (wherein the aryl may be substituted with a heteroaryl having 2 to 10 carbon atoms), a heteroaryl having 2 to 20 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 10 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 10 carbon atoms), an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms;
provided that at least one of the ring a, ring b and ring c is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on at least one of the ring a, ring b and ring c via a phenylene group;
^Y1 is B or P=O;
^X1 and ^X2 are >O;
In the case of a polymer, it is a dimer or trimer having two or three unit structures represented by general formula (2), and
At least one of the ring a, ring b and ring c has a group represented by general formula (oR) bonded at *;
In the above formula (oR), R ²¹ is an alkyl group having 1 to 4 carbon atoms, and R ²² to R ²⁵ are each independently a hydrogen atom, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms.
The electron transporting or injecting material according to claim 5 . In the above formula (2),
R ¹ to R ¹¹ are each independently a hydrogen atom, an aryl having 6 to 16 carbon atoms (wherein the aryl may be substituted with a heteroaryl having 2 to 10 carbon atoms), a heteroaryl having 2 to 20 carbon atoms, a diarylamino (wherein the aryl is an aryl having 6 to 10 carbon atoms), a diarylboryl (wherein the aryl is an aryl having 6 to 10 carbon atoms), an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms;
provided that at least one of the ring a, ring b and ring c is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on at least one of the ring a, ring b and ring c via a phenylene group;
^Y1 is B;
^X1 and ^X2 are >O;
In the case of a polymer, it is a dimer or trimer having two or three unit structures represented by general formula (2), and
At least one of the ring a, ring b and ring c has a group represented by general formula (oR) bonded at *;
In the above formula (oR), R ²¹ is an alkyl group having 1 to 4 carbon atoms, and R ²² to R ²⁵ are each independently a hydrogen atom, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms.
The electron transporting or injecting material according to claim 5 . In the above formula (2),
The ring a is substituted with a diphenylamino group, a carbazolyl group or a benzocarbazolyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms, and these groups may be substituted on the ring a via a phenylene group;
a group represented by general formula (oR) is bonded to the ring b and/or ring c at *;
The electron transport material or electron injection material according to any one of claims 5 to 10. The electron transport material or electron injection material according to any one of claims 5 to 11, wherein in the above formula (2), the halogen is fluorine. An electron transport material or electron injection material comprising a polycyclic aromatic compound represented by any one of the following structural formulas:

(In each formula, "Me" is methyl.) An organic electroluminescent device having a pair of electrodes consisting of an anode and a cathode, a light-emitting layer disposed between the pair of electrodes, and an electron transport layer and/or an electron injection layer disposed between the cathode and the light-emitting layer and containing the electron transport material or electron injection material described in any one of claims 1 to 13. The organic electroluminescence device according to claim 14, wherein at least one of the electron transport layer and the electron injection layer contains at least one selected from the group consisting of borane derivatives, pyridine derivatives, fluoranthene derivatives, BO-based derivatives, anthracene derivatives, benzofluorene derivatives, phosphine oxide derivatives, pyrimidine derivatives, carbazole derivatives, triazine derivatives, benzimidazole derivatives, phenanthroline derivatives, and quinolinol-based metal complexes. The organic electroluminescence device according to claim 15, wherein the electron transport layer and/or the electron injection layer further contains at least one selected from the group consisting of alkali metals, alkaline earth metals, rare earth metals, oxides of alkali metals, halides of alkali metals, oxides of alkaline earth metals, halides of alkaline earth metals, oxides of rare earth metals, halides of rare earth metals, organic complexes of alkali metals, organic complexes of alkaline earth metals, and organic complexes of rare earth metals. A display device or lighting device comprising the organic electroluminescent element according to any one of claims 14 to 16.

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