JP4783614B2 - Organic electroluminescence device - Google Patents

Description

  The present invention relates to an organic electroluminescence device capable of emitting light by converting electric energy into light.

  Research and development related to various display devices are actively conducted today, and organic electroluminescence (EL) devices are attracting attention because they can emit light with high luminance at a low voltage. Recently, improvement of element durability has been demanded, and improvement of this has been demanded.

Various aromatic fused-ring hydrocarbon materials have been proposed as suitable materials for improving the durability of the element. For example, Patent Documents 1 and 2 disclose diphenylanthracene derivatives.
However, condensed aromatic cyclic material, such as above for generally less energy level T _1, it is disadvantageous in terms of energy transfer efficiency for the dopant. In order to improve the luminous efficiency, it is desired to develop an aromatic hydrocarbon material having a higher T ₁ energy level.
JP-A-8-12600 JP 2001-335516 A

  An object of the present invention is to provide a light-emitting element having excellent light-emitting characteristics and high durability, in particular, a blue light-emitting element and a multicolor light-emitting element. A further object of the present invention is to provide an electron transport material and / or a host material for an organic electroluminescent device.

  The above problems have been achieved by the following means.

(1) An organic electroluminescent device having at least one organic layer including a light emitting layer between a pair of electrodes, wherein the organic layer is composed of a compound represented by the following general formula (2) (having a partial structure) An organic electroluminescence device comprising at least one kind. In the present specification, the compound (having a partial structure) represented by the general formula (2) is a compound represented by the general formula (2) and / or the compound represented by the general formula (2). It means a compound having the above corresponding group as a partial structure.)

一般式（２）中、A¹、A²、A³、A⁴、A⁵、A⁶、A⁷、A⁸、A⁹、A¹⁰、A¹¹、A¹²、A¹³、A¹⁴、A¹⁵およびA¹⁶は置換基を有していてもよい炭素原子もしくは窒素原子を表し、A¹、A²、A³、A⁴、A⁵、A⁶、A⁷、A⁸、A⁹、A¹⁰、A¹¹、A¹²、A¹³、A¹⁴、A¹⁵およびA¹⁶のうち少なくとも一つは窒素原子である。
（２）前記一般式（２）で表される化合物がテトラフェニレン構造を一つのみ有する化合物であることを特徴とする（１）記載の有機電界発光素子。
（３）前記一般式（２）で表される化合物に構造上相当する基を部分構造として有する化合物が、前記一般式（２）で表される化合物が互いに複数結合した、連結化合物、オリゴマー化合物またはポリマー化合物であることを特徴とする（１）記載の有機電界発光素子。
（４）前記一般式（２）で表される（部分構造を有する）化合物のテトラフェニレン構造中、１つの６員環が有する窒素原子が２個以下であることを特徴とする（１）〜（３）のいずれか１項に記載の有機電界発光素子。
（５）前記一般式（２）で表される（部分構造を有する）化合物のテトラフェニレン構造を形成する６員環のうち、窒素原子を有する６員環が置換基を有していないことを特徴とする（１）〜（４）のいずれか１項に記載の有機電界発光素子。
（６）前記一般式（２）で表される（部分構造を有する）化合物の少なくとも１種とりん光発光材料を含有することを特徴とする（１）〜（５）のいずれか１項に記載の有機電界発光素子。
（７）（１）〜（６）のいずれか１項に記載の有機電界発光素子を有する表示素子。

In the general formula ^{(2), A 1, A} 2, A 3, A 4, A 5, A 6, A 7, A 8, A 9, A 10, A 11, A 12, A 13, A 14, A ¹⁵ and A ^{16 each} represents an optionally substituted carbon atom or nitrogen atom, and A ¹ , A ² , A ³ , A ⁴ , A ⁵ , A ⁶ , A ⁷ , A ⁸ , A ⁹ , A ^At least one of ¹⁰ , A ¹¹ , A ¹² , A ¹³ , A ¹⁴ , A ¹⁵ and A ¹⁶ is a nitrogen atom.
(2) The organic electroluminescent element as described in (1), wherein the compound represented by the general formula (2) is a compound having only one tetraphenylene structure.
(3) A linking compound or oligomer compound in which a compound having a structurally equivalent group as the partial structure of the compound represented by the general formula (2) is bonded to the compound represented by the general formula (2). Or it is a polymer compound, The organic electroluminescent element as described in (1) characterized by the above-mentioned.
(4) In the tetraphenylene structure of the compound represented by the general formula (2) (having a partial structure), one 6-membered ring has 2 or less nitrogen atoms, (1) to The organic electroluminescent element according to any one of (3).
(5) Among the 6-membered rings forming the tetraphenylene structure of the compound represented by the general formula (2) (having a partial structure), the 6-membered ring having a nitrogen atom has no substituent. The organic electroluminescent element according to any one of (1) to (4), which is characterized in that
(6) In any one of (1) to (5), containing at least one compound (having a partial structure) represented by the general formula (2) and a phosphorescent material. The organic electroluminescent element as described.
(7) A display device having the organic electroluminescent device according to any one of (1) to (6).

  The organic electroluminescent element of the present invention exhibits excellent luminescent properties and durability.

The present inventors have intensively studied to solve the above technical problem and found that specific tetraphenylene derivatives have a high T ₁ energy level. When these are used in a triplet light emitting device, light emission occurs. It has been found that an element having high efficiency and excellent driving durability can be obtained. In addition, it has been found that the durability is further improved in a light emitting device containing a compound responsible for electron injection and transport in the light emitting layer of the light emitting device. This will be described in detail below.

  The organic electroluminescent element of the present invention is an organic electroluminescent element having at least one organic layer including a light emitting layer between a pair of electrodes, wherein the organic layer includes a compound represented by the following general formula (2) and The compound contains at least one selected from compounds having a structurally equivalent group as a partial structure.

一般式（２）について説明する。一般式（２）中、A¹、A²、A³、A⁴、A⁵、A⁶、A⁷、A⁸、A⁹、A¹⁰、A¹¹、A¹²、A¹³、A¹⁴、A¹⁵およびA¹⁶は置換基を有していてもよい炭素原子もしくは窒素原子を表し、A¹、A²、A³、A⁴、A⁵、A⁶、A⁷、A⁸、A⁹、A¹⁰、A¹¹、A¹²、A¹³、A¹⁴、A¹⁵およびA¹⁶のうち少なくとも一つは窒素原子である。

The general formula (2) will be described. In the general formula ^{(2), A 1, A} 2, A 3, A 4, A 5, A 6, A 7, A 8, A 9, A 10, A 11, A 12, A 13, A 14, A ¹⁵ and A ^{16 each} represents an optionally substituted carbon atom or nitrogen atom, and A ¹ , A ² , A ³ , A ⁴ , A ⁵ , A ⁶ , A ⁷ , A ⁸ , A ⁹ , A ^At least one of ¹⁰ , A ¹¹ , A ¹² , A ¹³ , A ¹⁴ , A ¹⁵ and A ¹⁶ is a nitrogen atom.

  Examples of the substituent are preferably halogen atoms (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), alkyl groups (preferably alkyl groups having 1 to 30 carbon atoms, for example, methyl, ethyl, n-propyl). , Isopropyl, t-butyl, n-octyl, 2-ethylhexyl), a cycloalkyl group (preferably a substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, such as cyclohexyl, cyclopentyl, 4-n-dodecyl) Cyclohexyl), a bicycloalkyl group (preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms. For example, bicyclo [1,2,2] heptan-2-yl, bicyclo [2,2,2] o Tan-3-yl),

  An alkenyl group (preferably a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms such as vinyl, allyl), a cycloalkenyl group (preferably a substituted or unsubstituted cycloalkenyl group having 3 to 30 carbon atoms, That is, it is a monovalent group in which one hydrogen atom of a cycloalkene having 3 to 30 carbon atoms is removed, for example, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl), bicycloalkenyl group (substituted or An unsubstituted bicycloalkenyl group, preferably a substituted or unsubstituted bicycloalkenyl group having 5 to 30 carbon atoms, that is, a monovalent group in which one hydrogen atom of a bicycloalkene having one double bond is removed. , Bicyclo [2,2,1] hept-2-en-1-yl, bicyclo [2,2,2] oct-2-ene- -Yl), an alkynyl group (preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, such as ethynyl, propargyl), an aryl group (preferably a substituted or unsubstituted aryl having 6 to 30 carbon atoms) Groups such as phenyl, p-tolyl, naphthyl), heterocyclic groups (preferably mono- or 5-membered substituted or unsubstituted, aromatic or non-aromatic heterocyclic compounds with one hydrogen atom removed. More preferably a 5- or 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms (for example, 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl),

  A cyano group, a hydroxyl group, a nitro group, a carboxyl group, an alkoxy group (preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms such as methoxy, ethoxy, isopropoxy, t-butoxy, n-octyloxy 2-methoxyethoxy), an aryloxy group (preferably a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, such as phenoxy, 2-methylphenoxy, 4-t-butylphenoxy, 3-nitrophenoxy 2-tetradecanoylaminophenoxy), silyloxy groups (preferably silyloxy groups having 3 to 20 carbon atoms, such as trimethylsilyloxy, t-butyldimethylsilyloxy), heterocyclic oxy groups (preferably carbon atoms) 2-30 substituted or unsubstituted heterocyclic oxy 1-phenyltetrazol-5-oxy, 2-tetrahydropyranyloxy), acyloxy group (preferably formyloxy group, substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, 6 to 30 carbon atoms) Substituted or unsubstituted arylcarbonyloxy groups such as formyloxy, acetyloxy, pivaloyloxy, stearoyloxy, benzoyloxy, p-methoxyphenylcarbonyloxy), carbamoyloxy groups (preferably substituted with 1 to 30 carbon atoms) Or an unsubstituted carbamoyloxy group such as N, N-dimethylcarbamoyloxy, N, N-diethylcarbamoyloxy, morpholinocarbonyloxy, N, N-di-n-octylaminocarbonyloxy, Nn-octylcarba Yloxy), an alkoxycarbonyloxy group (preferably a substituted or unsubstituted alkoxycarbonyloxy group having 2 to 30 carbon atoms, such as methoxycarbonyloxy, ethoxycarbonyloxy, t-butoxycarbonyloxy, n-octylcarbonyloxy), aryl Oxycarbonyloxy group (preferably a substituted or unsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms, such as phenoxycarbonyloxy, p-methoxyphenoxycarbonyloxy, pn-hexadecyloxyphenoxycarbonyloxy) ,

  An amino group (preferably an amino group, a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, a substituted or unsubstituted anilino group having 6 to 30 carbon atoms, such as amino, methylamino, dimethylamino, Anilino, N-methyl-anilino, diphenylamino), acylamino group (preferably formylamino group, substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, substituted or unsubstituted group having 6 to 30 carbon atoms) Arylcarbonylamino groups such as formylamino, acetylamino, pivaloylamino, lauroylamino, benzoylamino), aminocarbonylamino groups (preferably substituted or unsubstituted aminocarbonylamino having 1 to 30 carbon atoms, such as carbamoyl Amino, N, N-dimethylami Carbonylamino, N, N-diethylaminocarbonylamino, morpholinocarbonylamino), alkoxycarbonylamino group (preferably a substituted or unsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms, such as methoxycarbonylamino, ethoxycarbonylamino, t -Butoxycarbonylamino, n-octadecyloxycarbonylamino, N-methyl-methoxycarbonylamino), an aryloxycarbonylamino group (preferably a substituted or unsubstituted aryloxycarbonylamino group having 7 to 30 carbon atoms, for example, Phenoxycarbonylamino, p-chlorophenoxycarbonylamino, mn-octyloxyphenoxycarbonylamino), sulfamoylamino group (preferably having 0 to 30 carbon atoms) Substituted or unsubstituted sulfamoylamino groups such as sulfamoylamino, N, N-dimethylaminosulfonylamino, Nn-octylaminosulfonylamino), alkyl and arylsulfonylamino groups (preferably having carbon atoms) 1-30 substituted or unsubstituted alkylsulfonylamino, substituted or unsubstituted arylsulfonylamino having 6 to 30 carbon atoms, such as methylsulfonylamino, butylsulfonylamino, phenylsulfonylamino, 2,3,5-tri Chlorophenylsulfonylamino, p-methylphenylsulfonylamino), mercapto group, alkylthio group (preferably a substituted or unsubstituted alkylthio group having 1 to 30 carbon atoms, such as methylthio, ethylthio, n-hexadecylthio), ant Ruthio group (preferably substituted or unsubstituted arylthio having 6 to 30 carbon atoms, such as phenylthio, p-chlorophenylthio, m-methoxyphenylthio), heterocyclic thio group (preferably substituted having 2 to 30 carbon atoms) Or an unsubstituted heterocyclic thio group such as 2-benzothiazolylthio, 1-phenyltetrazol-5-ylthio),

Sulfamoyl group (preferably a substituted or unsubstituted sulfamoyl group having 0 to 30 carbon atoms such as N-ethylsulfamoyl, N- (3-dodecyloxypropyl) sulfamoyl, N, N-dimethylsulfamoyl, N -Acetylsulfamoyl, N-benzoylsulfamoyl, N- (N′-phenylcarbamoyl) sulfamoyl), sulfo group, alkyl and arylsulfinyl group (preferably substituted or unsubstituted alkyl having 1 to 30 carbon atoms) Sulfinyl group, 6-30 substituted or unsubstituted arylsulfinyl group (for example, methylsulfinyl, ethylsulfinyl, phenylsulfinyl, p-methylphenylsulfinyl),
Alkyl and arylsulfonyl groups (preferably substituted or unsubstituted alkylsulfonyl groups having 1 to 30 carbon atoms, substituted or unsubstituted arylsulfonyl groups having 6 to 30 carbon atoms such as methylsulfonyl, ethylsulfonyl, phenylsulfonyl, p -Methylphenylsulfonyl), an acyl group (preferably a formyl group, a substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms, a substituted or unsubstituted arylcarbonyl group having 7 to 30 carbon atoms, such as acetyl, Pivaloylbenzoyl), an aryloxycarbonyl group (preferably a substituted or unsubstituted aryloxycarbonyl group having 7 to 30 carbon atoms such as phenoxycarbonyl, o-chlorophenoxycarbonyl, m-nitrophenoxycarbonyl, p- t-butyl Enoxycarbonyl), alkoxycarbonyl group (preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, t-butoxycarbonyl, n-octadecyloxycarbonyl), carbamoyl group (Preferably, a substituted or unsubstituted carbamoyl having 1 to 30 carbon atoms such as carbamoyl, N-methylcarbamoyl, N, N-dimethylcarbamoyl, N, N-di-n-octylcarbamoyl, N- (methylsulfonyl) ) Carbamoyl), aryl and heterocyclic azo groups (preferably substituted or unsubstituted arylazo groups having 6 to 30 carbon atoms, substituted or unsubstituted heterocyclic azo groups having 3 to 30 carbon atoms, such as phenylazo, p -Chlorophenylazo, 5 Ethylthio-1,3,4-thiadiazol-2-ylazo), imide group (preferably N-succinimide, N-phthalimide), phosphino group (preferably a substituted or unsubstituted phosphino group having 2 to 30 carbon atoms) , For example, dimethylphosphino, diphenylphosphino, methylphenoxyphosphino), phosphinyl group (preferably a substituted or unsubstituted phosphinyl group having 2 to 30 carbon atoms, such as phosphinyl, dioctyloxyphosphinyl, diethoxy Phosphinyl), a phosphinyloxy group (preferably a substituted or unsubstituted phosphinyloxy group having 2 to 30 carbon atoms, such as diphenoxyphosphinyloxy, dioctyloxyphosphinyloxy), phosphinyl Finylamino group (preferably having 2 to 30 carbon atoms A substituted or unsubstituted phosphinylamino group such as dimethoxyphosphinylamino, dimethylaminophosphinylamino), a silyl group (preferably a substituted or unsubstituted silyl group having 3 to 30 carbon atoms, such as , Trimethylsilyl, t-butyldimethylsilyl, phenyldimethylsilyl).

  Among the above substituents, those having a hydrogen atom may be substituted with the above groups after removing this. Examples of such functional groups include an alkylcarbonylaminosulfonyl group, an arylcarbonylaminosulfonyl group, an alkylsulfonylaminocarbonyl group, and an arylsulfonylaminocarbonyl group. Examples thereof include methylsulfonylaminocarbonyl, p-methylphenylsulfonylaminocarbonyl, acetylaminosulfonyl, and benzoylaminosulfonyl groups. The substituents may be condensed to form a condensed ring.

More preferably, the substituent is an alkyl group having 1 to 3 carbon atoms (for example, methyl, ethyl, isopropyl), a halogen atom (for example, chlorine atom or fluorine atom), a substituted or unsubstituted group having 6 to 12 carbon atoms. Aryl groups (e.g., phenyl, naphthyl), substituted or unsubstituted heterocyclic groups having 1 to 10 carbon atoms (e.g., pyridyl, imidazolyl), and the like. Is mentioned.
Among the divalent 6-membered ring groups forming a tetraphenylene structure in the compound represented by the general formula (2), the divalent 6-membered ring group having a nitrogen atom is a substituent except for the formation of a condensed ring. It is preferable not to have. Furthermore, in the tetraphenylene structure of the compound represented by the general formula (2), the number of nitrogen atoms in one divalent 6-membered ring group is preferably 3 or less, and preferably 2 or less. More preferred.
In general formula (2), at least one of A ^{1 to} A ¹⁶ is a nitrogen atom, and particularly preferably A ¹ , A ⁴ , A ⁵ , A ⁸ , A ⁹ , A ¹² , A ¹³ , and atom selected from the group consisting of a ¹⁶ is a nitrogen atom. Further, two or more of A ^{1 to} A ¹⁶ are more preferably nitrogen atoms, more preferably one bivalent 6-membered ring represents a pyrimidine ring or a pyrazine ring, and most preferably represents a pyrazine ring. preferable.

  The compound represented by the general formula (2) preferably has only one tetraphenylene structure. In the present invention, the tetraphenylene structure refers to a structure in which a divalent 6-membered ring group is condensed on four sides as shown in the general formula (2), and does not mean that the condensed ring is limited to a phenylene group. Therefore, the atoms constituting the 6-membered ring may be other than carbon atoms such as nitrogen atoms. Having only one tetraphenylene structure means that it has no substituent having a tetraphenylene structure other than the tetraphenylene structure which is the basic skeleton of the compound represented by the general formula (2). However, this does not apply to the connecting compounds (multimers), oligomer compounds, polymer compounds and the like described below.

  The compound of the general formula (2) may be a single compound, or may be a compound connected through a linking group, or a compound in which any hydrogen atom or the like is detached and connected. Good. For example, a dimer or more multimer formed by combining two or more may be used. Moreover, the compound of General formula (2) is a low molecular weight compound, an oligomer compound, or a polymer compound (The weight average molecular weight (polystyrene conversion) becomes like this. Preferably it is 1,000-5,000,000, More preferably, it is 2,000- 1,000,000, more preferably 3,000 to 100,000). In the case of the polymer compound, the compound represented by the general formula (2) may be contained in the polymer main chain or in the polymer side chain. In the case of a polymer compound, it may be a homopolymer compound or a copolymer. The compound represented by the general formula (2) used in the organic electroluminescence device of the present invention is preferably a low molecular compound.

The T ₁ level (energy level of the lowest triplet excited state) of the compound represented by the general formula (2) is 45 Kcal / mol or more (188.3 KJ / mol or more), 85 Kcal / mol or less (355.6 KJ / mol or less). Is preferably 55 Kcal / mol or more (251.0 KJ / mol or more), 85 Kcal / mol or less (355.6 KJ / mol or less), more preferably 60 Kcal / mol or more (272.0 KJ / mol or more), 85 Kcal / mol or less ( 355.6 KJ / mol or less) is more preferable.

  Next, although the compound of General formula (2) used for the organic electroluminescent element of this invention is illustrated, this invention is not limited to this.

The compound represented by the general formula (2) used in the organic electroluminescence device of the present invention is, for example, Justus Liebigs Annalen der Chemie, 751, 1 (1971), Tetrahedron Letters, 39, 5393 (1998), Journal of It can be synthesized by the method described in Organomet. Chem. 10, 471 (1967), Angelwandte Chemie, International Edition in English, 87, 746 (1975).
Specifically, it can be synthesized using various conventional aromatic carbon-carbon bond forming reactions or carbon-nitrogen bond forming reactions. For example, halogen compounds having a tetraphenylene skeleton and boric acid derivatives, or halogens having a tetraphenylene skeleton. It can be synthesized by a reaction between a compound and an aromatic amine compound in the presence of a palladium catalyst.

  For example, the exemplified compound (2-17) is obtained by referring to the methods described in Chemistry A European Journal 8 (9), 2000-2004 (2002) and Angelwandte Chemie, the International Edition in English 36, 1607-1609 (1997). And can be synthesized according to the following scheme, but is not limited thereto.

  The organic electroluminescent element of the present invention can be used regardless of the excited state of the luminescent material, but is preferably an element utilizing light emission from the triplet excited state. Here, light emission from the triplet excited state is synonymous with phosphorescence emission (hereinafter, a phosphorescent material is referred to as a “phosphorescent material”). When the organic electroluminescent element of the present invention is composed of a phosphorescent material, it preferably contains at least one phosphorescent material. At this time, the phosphorescent material used in the present invention is not particularly limited, but a transition metal complex is preferable. Among transition metal complexes, orthometalated complexes can be used very preferably. Orthometalated Complex is “Organic Metal Chemistry Fundamentals and Applications” written by Akio Yamamoto, p. 150 and p. 232, Houbobo (1982), “Photochemistry and Photophysics of Coordination Compounds” by H. Yersin. 71-77 and 135-146, Springer-Verlag (1987), etc. The central metal of the transition metal complex is not particularly limited, and is preferably iridium, platinum, rhenium or ruthenium, more preferably iridium or platinum, and particularly preferably platinum. The transition metal complex is preferably a tridentate or higher multidentate complex, and more preferably a tetradentate or higher multidentate complex. Specific examples of the multidentate coordination complex include the general formulas (1) to (18) described in the pamphlet of International Publication WO04 / 099339 or the general formulas (1) to (18) described in the pamphlet of International Publication WO04 / 108857. The complex represented by (12) is mentioned.

The phosphorescent material preferably has a phosphorescence quantum yield of 70% or more at 20 ° C., more preferably a phosphorescence quantum yield at 20 ° C. of 80% or more, and phosphorescence at 20 ° C. It is particularly preferable that the photon yield is 85% or more.
Further, the present invention can be applied to light emitting elements in any wavelength region, but it is preferable that the wavelength region is phosphorescent λmax (emission maximum value) of 495 nm or less, which is considered to be technically difficult. The phosphorescence λmax is preferably 480 nm or less, more preferably 470 nm or less, further preferably 465 nm or less, and particularly preferably 460 nm or less.
Hereinafter, preferred embodiments of the compound represented by the general formula (2) will be described in more detail, but the same applies to the compound having a partial structure represented by the general formula (2).
The compound represented by the general formula (2) may be contained in any layer in the organic electroluminescence device of the present invention, but is preferably contained in the organic layer, and in the electron transport layer or the light emitting layer. It is more preferable that it is contained in. In addition, one or more compounds represented by the general formula (2) may be included in the organic electroluminescence device. When a plurality of compounds are included, they may be included in the same layer or in a plurality of layers. It may be. Furthermore, the compound represented by the general formula (2) may be contained in the same or different organic layer in the organic electroluminescent element together with other light emitting materials or phosphorescent materials.

  The system, driving method, usage form and the like of the organic electroluminescence device of the present invention are not particularly limited, but the form represented by the general formula (2) is used as the charge transport material, and the general formula (2). In a preferred embodiment, the compound and the phosphorescent material are used in the same layer. When the compound represented by the general formula (2) and the phosphorescent material are used in the same layer, the compound represented by the general formula (2) mainly functions as a host material. As a typical light emitting element, an organic EL (electroluminescence) element can be given.

  When the compound represented by the general formula (2) is included in the light emitting layer of the organic electroluminescent element of the present invention, the compound b responsible for hole injection and transport may be included together with these.

  The compound that injects and transports holes contained in the light emitting layer means a compound that plays a role of injecting and transporting holes in the light emitting layer. By adding the compound to the light emitting layer, It is a compound that promotes hole injection or transport, or a compound that has an Ip value (ionization potential) suitable for hole injection / transport.

  When a compound responsible for hole injection / transport is included in the light emitting layer, the driving voltage can be lowered by facilitating the injection of holes into the light emitting layer, thereby applying a high electric field. The decomposition of the material derived from can be suppressed. In addition, since the compound b is responsible for hole transport, decomposition of the material that occurs when holes are injected into the compound represented by the general formula (2) can be suppressed.

  When the light emitting layer contains the compound b responsible for hole injection / transport together with the compound represented by the general formula (2), the concentration in the light emitting layer is 10 for the compound represented by the general formula (2). It is preferable that the compound b for injecting and transporting holes is 1 to 90% by mass, and the compound represented by the general formula (2) is 15 to 98% by mass, injecting and transporting holes. The compound b is more preferably 2 to 85% by mass, the compound represented by the general formula (2) is 20 to 95% by mass, and the compound b for injecting and transporting holes is 5 to 80% by mass or less. It is particularly preferred.

  The organic electroluminescent device of the present invention has at least one organic layer including a light emitting layer (including a single light emitting layer, hereinafter also referred to as “organic compound layer”) between a pair of electrodes (anode and cathode). At least one of the layers contains a compound represented by the general formula (2). The mass ratio of the compound in the layer containing the compound represented by the general formula (2) is preferably 50 to 99.9% by mass when the compound represented by the general formula (2) is used as a host material. Yes, more preferably 60 to 99% by mass. When used as a charge transport material, it is preferably 50 to 100% by mass, more preferably 60 to 100% by mass.

  The method for forming the layer containing the compound represented by the general formula (2) is not particularly limited, and methods such as resistance heating vapor deposition, electron beam, sputtering, molecular lamination, coating, ink jet, and printing Can be used. Among these, the resistance heating vapor deposition method, the coating method, and the transfer method are preferable in terms of device characteristics and manufacturing.

  The organic electroluminescent device of the present invention may contain a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a protective layer and the like in addition to the light emitting layer, and each of these layers has other functions. It may be provided. The compound represented by the general formula (2) used in the organic electroluminescence device of the present invention may be contained in any of these layers.

  In the organic electroluminescent device of the present invention, it is preferable to provide a layer containing a compound having an ionization potential of 5.9 eV or more between the cathode and the light emitting layer. The ionization potential is particularly preferably 6.0 eV or more, and such a layer is particularly preferably an electron transport layer.

  The light emission maximum wavelength of the organic electroluminescence device of the present invention is preferably 390 to 495 nm, more preferably 400 to 490 nm from the viewpoint of blue color purity. In addition, the organic electroluminescent device of the present invention may have a light emission maximum wavelength of 500 nm or more, and may be a white light emitting device. From the viewpoint of blue color purity, the x value of the CIE chromaticity value of luminescence is preferably 0.22 or less, more preferably 0.20 or less, and the y value of the CIE chromaticity value of luminescence is preferably 0.53 or less, more preferably 0.50. It is as follows. From the viewpoint of blue color purity, the half width of the emission spectrum is preferably 100 nm or less, more preferably 90 nm or less, still more preferably 80 nm or less, and particularly preferably 70 nm or less. Hereinafter, each layer of the organic electroluminescent element of the present invention will be described in detail.

(A) Anode The anode supplies holes to a hole injection layer, a hole transport layer, a light emitting layer, and the like. As a material for forming the anode, a metal, an alloy, a metal oxide, an electrically conductive compound, a mixture thereof, or the like can be used, and a material having a work function of 4 eV or more is preferably used. Specific examples include metals (gold, silver, chromium, nickel, etc.), conductive metal oxides (tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), etc.), these metals and conductive metal oxides. A mixture or laminate of the above, an inorganic conductive material (copper iodide, copper sulfide, etc.), an organic conductive material (polyaniline, polythiophene, polypyrrole, etc.) and a laminate of these with ITO. The anode is preferably made of a conductive metal oxide, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  The method for forming the anode may be appropriately selected according to the material used. For example, in the case of ITO, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (sol-gel method, etc.), an indium tin oxide dispersion A method such as coating can be used. By performing a treatment such as cleaning on the anode, the driving voltage of the light emitting element can be lowered or the light emission efficiency can be increased. For example, in the case of an anode made of ITO, UV-ozone treatment, plasma treatment, etc. are effective. The sheet resistance of the anode is preferably several hundred Ω / □ or less. The thickness of the anode can be appropriately selected depending on the material, but is usually preferably 10 nm to 5 μm, more preferably 50 nm to 1 μm, and particularly preferably 100 to 500 nm.

  The anode is usually formed on a substrate made of soda lime glass, non-alkali glass, transparent resin or the like. In the case of a glass substrate, it is preferable to use an alkali-free glass in order to reduce ions eluted from the glass. When a soda lime glass substrate is used, it is preferable to previously form a barrier coat such as silica on the surface thereof. The thickness of the substrate is not particularly limited as long as it is sufficient to maintain the mechanical strength, but in the case of a glass substrate, it is usually 0.2 mm or more, preferably 0.7 mm or more.

(B) Cathode The cathode supplies electrons to an electron injection layer, an electron transport layer, a light emitting layer, and the like. As materials for the cathode, metals, alloys, metal halides, metal oxides, electrically conductive compounds, mixtures thereof, and the like can be used. Adhesion with adjacent layers such as a light-emitting layer, ionization potential, and stability It may be selected in consideration of the above.
Specific examples include alkali metals (lithium (Li), sodium (Na), potassium (K), etc.) and their fluorides and oxides, alkaline earth metals (magnesium (Mg), calcium (Ca), etc.) and their Alloys and mixed metals of fluorides and oxides, gold, silver, lead, aluminum, sodium and potassium, alloys and mixed metals of lithium and aluminum, alloys and mixed metals of magnesium and silver, rare earth metals (indium, ytterbium Etc.) and mixtures thereof. The cathode is preferably made of a material having a work function of 4 eV or less, and more preferably made of aluminum, an alloy or mixed metal composed of lithium and aluminum, or an alloy or mixed metal composed of magnesium and silver.

  The cathode may have a single layer structure made of the above materials or a laminated structure including layers made of the above materials. For example, a laminated structure of aluminum / lithium fluoride, aluminum / lithium oxide or the like is preferable. The cathode can be formed by an electron beam method, a sputtering method, a resistance heating vapor deposition method, a coating method, or the like. In the case of the vapor deposition method, the material can be vapor-deposited alone, or two or more materials can be vapor-deposited simultaneously. When the alloy electrode is formed, a plurality of metals can be formed by simultaneous vapor deposition, or a previously prepared alloy may be vapor deposited. The sheet resistance of the cathode is preferably several hundred Ω / □ or less. The thickness of the cathode can be appropriately selected depending on the material, but is usually preferably 10 nm to 5 μm, more preferably 50 nm to 1 μm, and particularly preferably 100 nm to 1 μm.

(C) Hole injection layer and hole transport layer The materials used for the hole injection layer and the hole transport layer have the function of injecting holes from the anode, the function of transporting holes, and the electrons injected from the cathode. Any one having a function of blocking may be used. Specific examples include carbazole, triazole, oxazole, oxadiazole, imidazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatic group Tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole), aniline copolymers, conductive polymers such as thiophene oligomers and polythiophenes, organic silanes , Compounds represented by the above general formula (2), derivatives thereof, carbon and the like.

  The hole injection layer and the hole transport layer may have a single layer structure made of one or more kinds of the above materials, or may have a multilayer structure made of a plurality of layers having the same composition or different compositions. As a method for forming the hole injection layer and the hole transport layer, a vacuum deposition method, an LB method, a method in which the above materials are dissolved or dispersed in a solvent (a spin coating method, a casting method, a dip coating method, etc.), An ink jet method, a printing method, a transfer method, or the like is used. In the case of a coating method, a coating solution may be prepared by dissolving or dispersing the above materials together with a resin component. Examples of the resin component include polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone. , Polyphenylene oxide, polybutadiene, poly (N-vinylcarbazole), hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, polyvinyl acetate, ABS resin, polyurethane, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin Silicon resin or the like can be used. The thickness of the hole injection layer and the hole transport layer is not particularly limited, but is usually preferably 1 nm to 5 μm, more preferably 5 nm to 1 μm, and particularly preferably 10 to 500 nm.

(D) Light-emitting layer When an electric field is applied to the light-emitting element, holes injected from the anode, hole injection layer, or hole transport layer in the light-emitting layer, and electrons injected from the cathode, electron injection layer, or electron transport layer, Recombine and emit light. The material forming the light-emitting layer has the function of receiving holes from the anode, etc. when an electric field is applied, the function of receiving electrons from the cathode, etc., the function of moving charges, and the function of emitting light by providing a field for recombination of holes and electrons. There is no particular limitation as long as it can form a layer having s. Examples of the material for the light emitting layer include benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, perylene, perinone, oxadiazole, aldazine, pyralidine, cyclopentadiene, bis Styrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, styrylamine, aromatic dimethylidin compounds, metal complexes (metal complexes of 8-quinolinol derivatives, etc.), polymer light emitting materials (polythiophene, polyphenylene, polyphenylene vinylene, etc.), organic silanes , Transition metal complexes (iridium trisphenylpyridine complex, platinum porphyrin complex, etc.), derivatives thereof, and the like can be used. At least one of the materials forming the light emitting layer is preferably a phosphorescent light emitting material.

  The light emitting layer may be formed of a single material or a plurality of materials. There may be one or more light emitting layers. Even when there are a plurality of light emitting layers, each light emitting layer may be formed of a single material or a plurality of materials. Further, the plurality of light emitting layers may emit light with different emission colors to emit white light or the like, or a single light emitting layer may emit white light.

  The formation method of the light emitting layer is not particularly limited. Resistance heating vapor deposition method, electron beam method, sputtering method, molecular lamination method, coating method (spin coating method, casting method, dip coating method, etc.), inkjet method, printing method, LB Method, transfer method and the like can be used. Of these, the resistance heating vapor deposition method and the coating method are preferable. The thickness of the light emitting layer is not particularly limited, and is usually preferably 1 nm to 5 μm, more preferably 5 nm to 1 μm, and particularly preferably 10 to 500 nm.

(E) Electron injection layer and electron transport layer The material forming the electron injection layer and the electron transport layer is any one of a function of injecting electrons from the cathode, a function of transporting electrons, and a function of blocking holes injected from the anode. As long as it has such. Specific examples include fragrances such as triazole, oxazole, oxadiazole, imidazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyrandioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, naphthalene, and perylene. Ring tetracarboxylic anhydride, phthalocyanine, metal complex (metal complex of 8-quinolinol derivative, metal phthalocyanine, metal complex having benzoxazole or benzothiazole as a ligand), organic silane, represented by the above general formula (2) Compounds, derivatives thereof, and the like.

  The electron injection layer and the electron transport layer may have a single layer structure made of one or more of the above materials, or may have a multilayer structure made of a plurality of layers having the same composition or different compositions. The electron injection layer and the electron transport layer can be formed by vacuum deposition, LB, coating by dissolving or dispersing the above materials in a solvent (spin coating, casting, dip coating, etc.), inkjet method The printing method, the transfer method, etc. are used. In the case of the coating method, the above material may be dissolved or dispersed together with the resin component to prepare a coating solution. As this resin component, the thing similar to the case of the positive hole injection layer and positive hole transport layer which were mentioned above can be used. The film thickness of the electron injection layer and the electron transport layer is not particularly limited, and is usually preferably 1 nm to 5 μm, more preferably 5 nm to 1 μm, and particularly preferably 10 to 500 nm.

(F) Protective layer The protective layer has a function of preventing substances that promote device deterioration such as moisture and oxygen from entering the device. Protective layer materials include metals (indium (In), tin (Sn), lead (Pb), gold (Au), copper (Cu), silver (Ag), aluminum (Al), titanium (Ti), nickel (Ni), etc.), metal oxides _{(MgO, SiO, SiO 2,} Al 2 O 3, GeO, NiO, CaO, BaO, Fe 2 O 3, Y 2 O 3, TiO 2 , etc.), metal fluorides (MgF ₂ , LiF, AlF ₃ , CaF ₂ etc.), nitride (SiNx, SiOxNy etc.), polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, chloro A copolymer of trifluoroethylene and dichlorodifluoroethylene, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer, and a fluorine-containing copolymer having a cyclic structure in the copolymer main chain Heavy For example, a water-absorbing substance having a water absorption of 1% or more, a moisture-proof substance having a water absorption of 0.1% or less, and the like can be used.

  The method for forming the protective layer is not particularly limited, and vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation ion plating) Method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method, etc. can be applied. The compound represented by the general formula (2) of the present invention can be synthesized by the method described in Angew. Chem., 87,746 (1975) or the method described in Chem. Ber., 36, 1607 (1997).

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to them.

[Example 1]
The cleaned ITO substrate was put into a vapor deposition apparatus, and TPD (N, N′-diphenyl-N, N′-di (m-tolyl) -benzidine) was vapor-deposited to a thickness of 40 nm, on which the exemplified compounds (2-3) and b Was co-evaporated at a mass ratio of 17 to 1, and 20 nm of the following azole compound c was further evaporated thereon. A mask patterned to have a light emitting area of 4 mm × 5 mm is placed on the obtained organic thin film, and magnesium and silver (magnesium: silver = 10: 1 (mass ratio)) are co-deposited by 50 nm in a vapor deposition apparatus. Then, 50 nm of silver was vapor-deposited to produce the light emitting device of Example 1.

  The obtained light-emitting element of Example 1 was made to emit light by applying a DC constant voltage using “source measure unit 2400 type” manufactured by Toyo Technica, and the luminance of the light-emitting element was used using “luminance meter BM-8” manufactured by Topcon Corporation. The emission wavelength was measured using “Spectrum Analyzer PMA-11” manufactured by Hamamatsu Photonics. As a result, blue light emission was obtained, and the external quantum efficiency was 4.2%. The external quantum efficiency was calculated from light emission luminance, light emission spectrum, current density, and specific luminous efficiency curve.

[Example 2]
A light emitting device of Example 2 was produced in the same manner as in Example 1 except that Example Compound (2-2) was used in place of Example Compound (2-3). As a result of measuring the light emission luminance of the light emitting device of Example 2 in the same manner as in Example 1, blue light emission was obtained, and the external quantum efficiency was 3.9%.

Example 3
A light emitting device of Example 3 was produced in the same manner as in Example 1 except that Example Compound (2-10) was used instead of Example Compound (2-3). As a result of measuring the light emission luminance of the light emitting device of Example 3 in the same manner as in Example 1, blue light emission was obtained, and the external quantum efficiency was 1.2%.

[Comparative Example 1]
A light emitting device of Comparative Example 1 was produced in the same manner as in Example 1 except that Compound a was used in place of Exemplary Compound (2-3). As a result of measuring the light emission luminance of the light emitting element of Comparative Example 1 in the same manner as in Example 1, blue light emission having a chromaticity value (0.21, 0.53) was obtained, and the external quantum efficiency was 1.2%.

[Comparative Example 2]
A light emitting device of Comparative Example 2 was produced in the same manner as in Example 1 except that the following compound d was used instead of the exemplified compound (2-3). As a result of measuring the light emission luminance and the light emission wavelength of the light emitting device of Comparative Example 2 in the same manner as in Example 1, blue light emission having a chromaticity value (0.18, 0.38) was obtained, and the external quantum efficiency was 0.3%.

Example 4
A light emitting device of Example 4 was produced in the same manner as in Example 1 except that Compound f was used instead of Compound b, and Example Compound (2-3) was used instead of Compound c. As a result of measuring the light emission luminance of the light emitting device of Example 4 in the same manner as in Example 1, the external quantum efficiency was 7.9%.

Example 5
A light emitting device of Example 5 was produced in the same manner as in Example 4 except that Example Compound (2-2) was used instead of Example Compound (2-3). As a result of measuring the light emission luminance of the light emitting device of Example 5 in the same manner as in Example 1, the external quantum efficiency was 9.0%.

Example 6
A light emitting device of Example 6 was produced in the same manner as in Example 4 except that Example Compound (2-10) was used instead of Example Compound (2-3). As a result of measuring the light emission luminance of the light emitting element of Example 6 in the same manner as in Example 1, the external quantum efficiency was 8.1%.

[Comparative Example 3]
A light emitting device of Comparative Example 3 was produced in the same manner as in Example 4 except that Compound h was used in place of Illustrative Compound (2-3). As a result of measuring the light emission luminance of the light emitting element of Comparative Example 3 in the same manner as in Example 1, the external quantum efficiency was 6.5%.

Example 7
The cleaned ITO substrate is placed in a vapor deposition apparatus, TPD is deposited to 40 nm, and the exemplified compound (2-3) and the following compound g are co-deposited at a mass ratio of 17: 1 to 5 nm thereon, and the exemplified compound (2 -2) and compound b were co-evaporated at a mass ratio of 17: 1 to 15 nm, and the exemplified compound (2-3) was further evaporated thereon by 40 nm. A mask patterned to have a light emitting area of 4 mm × 5 mm was placed on the obtained organic thin film, and after 3 nm of lithium fluoride was deposited in a vapor deposition apparatus, 60 nm of aluminum was evaporated to obtain the light emitting device of Example 7. Produced. As a result of measuring the light emission luminance and the light emission wavelength of the light emitting device of Example 7 in the same manner as in Example 1, white light emission with chromaticity values (0.33, 0.32) was obtained, and the external quantum efficiency of this light emitting device was calculated. It was 1%.

Example 8
Baytron P (PEDOT-PSS (polyethylenedioxythiophene-polystyrene sulfonic acid dope) solution, manufactured by Bayer) was spin-coated on a cleaned ITO substrate (1000 rpm, 30 sec) and vacuum dried at 150 ° C. for 1.5 hours. Thus, an organic layer having a thickness of 70 nm was obtained. Next, 18 mg of Exemplified Compound (2-2) and 2 mg of Compound b were dissolved in 1.5 ml of dichloroethane, and this was spin-coated on the organic layer to obtain a 110 nm organic thin film. After putting this into a vapor deposition apparatus and vacuum-depositing the exemplified compound (2-3) on the organic thin film by 40 nm, a mask patterned to have a light emitting area of 4 mm × 5 mm is installed, and lithium fluoride is deposited to 3 nm in the vapor deposition apparatus. After vapor deposition, 60 nm of aluminum was vapor-deposited to produce the light emitting device of Example 8. As a result of measuring the light emission luminance and the light emission wavelength of the light emitting device of Example 8 in the same manner as in Example 1, blue light emission was obtained, and the maximum luminance was 1100 cd / m ² .

The organic electroluminescent device of the present invention has high external quantum efficiency and excellent light emission characteristics, and can be applied to blue light emitting devices and white light emitting devices with high color purity, so that display devices, displays, backlights, electrophotography, illumination light sources, It can be suitably used for recording light sources, exposure light sources, reading light sources, signs, signboards, interiors, optical communications, and the like.

Claims (3)

An organic electroluminescent device having at least one organic layer including a light emitting layer between a pair of electrodes, wherein the organic layer includes a compound represented by the following general formula (2) and a group structurally equivalent to the compound An organic electroluminescent device comprising at least one selected from compounds having a partial structure.

In the general formula ^{(2), A 1, A} 2, A 3, A 4, A 5, A 6, A 7, A 8, A 9, A 10, A 11, A 12, A 13, A 14, A ¹⁵ and A ^{16 each} represents an optionally substituted carbon atom or nitrogen atom, and A ¹ , A ² , A ³ , A ⁴ , A ⁵ , A ⁶ , A ⁷ , A ⁸ , A ⁹ , A ^At least one of ¹⁰ , A ¹¹ , A ¹² , A ¹³ , A ¹⁴ , A ¹⁵ and A ¹⁶ is a nitrogen atom.   The organic electroluminescence device according to claim 1, wherein the compound represented by the general formula (2) is a compound having only one tetraphenylene structure. A compound having a group corresponding to the structure of the compound represented by the general formula (2) as a partial structure is a linked compound, oligomer compound or polymer compound in which a plurality of compounds represented by the general formula (2) are bonded to each other. The organic electroluminescent element according to claim 1, wherein: