JP7614600B2 - Enamine compound, material for organic electroluminescence device containing said enamine compound, and organic electroluminescence device having layer containing said enamine compound - Google Patents

Description

The present invention relates to an enamine compound, a material for an organic electroluminescent device having the enamine compound, and an organic electroluminescent device having a layer containing the enamine compound.

Organic electroluminescent devices have begun to be put to practical use, primarily for small mobile applications. However, to further expand their applications, performance improvements are essential, and there is a demand for materials that have low driving voltages, high luminous efficiency, and long life characteristics.

Patent Document 1 or 2 and Non-Patent Document 1 disclose enamine compounds that are materials for organic electroluminescent devices that can reduce the driving voltage with high efficiency.

Japanese Patent Application Publication No. 11-184110 JP 2006-269834 A

Dye and Pigment 168 (2019) 93-102

There is a strong demand from the market for an expansion of applications and environments in which they can be used, and the enamine compounds described in Patent Documents 1 to 3 do not fully satisfy the three characteristics of driving voltage, luminous efficiency, and life characteristics. In particular, there is a demand for compounds that achieve a higher level of durability to achieve a long life.

Therefore, one aspect of the present invention aims to provide an organic electroluminescent device that exhibits high luminous efficiency and has high durability in various applications or in various environments, an enamine compound that forms the device, and a material for the organic electroluminescent device that contains the enamine compound.

The objects of each aspect of the present invention have been achieved as follows.
1) An organic electroluminescent device having a layer containing a compound represented by the following general formula (1):

Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group which may have a substituent, and Ar ¹ and Ar ² may form a ring. Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent, and Ar ³ and Ar ⁴ may form a ring.
^R1 represents an aryl group, an alkyl group, a triarylsilyl group, a trialkylsilyl group, an alkoxy group, or an amino group, each of which may have a substituent. ^R1 is a single bond, and may form a ring together with ^Ar3 or ^Ar4 .
2) The organic electroluminescent device according to 1) above, wherein the total number of benzene rings possessed by Ar ¹ to Ar ⁴ and R ¹ is 7 or more, provided that when R ¹ forms a ring together with Ar ³ or Ar ⁴ and a nitrogen atom is included in the ring-forming atoms, the total number of benzene rings is 4 or more.
3) A compound represented by the following general formula (2):

Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group which may have a substituent, and Ar ¹ and Ar ² may form a ring. Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent, and Ar ³ and Ar ⁴ may form a ring.
^R2 represents an aryl group, an alkyl group, a triarylsilyl group, a trialkylsilyl group, or an alkoxy group, each of which may have a substituent. ^R2 is a single bond, and may form a ring together with ^Ar3 or ^Ar4 .
However, the total number of benzene rings possessed by Ar ¹ to Ar ⁴ and R ² is 7 or more. When R ² forms a ring together with Ar ³ or Ar ⁴ and a nitrogen atom is included in the ring-forming atoms, the total number of benzene rings is 4 or more.
4) A compound represented by the following general formula (3):

Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group which may have a substituent, and Ar ¹ and Ar ² may form a ring. Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent.
^R3 represents an amino group which may have a substituent.
5) A material for an organic electroluminescent device, comprising the compound according to 3) or 4).

According to one aspect of the present invention, it is possible to provide a novel enamine compound that forms an organic electroluminescent device exhibiting high-level life characteristics, and a material for an organic electroluminescent device that contains the enamine compound.

In addition, according to another aspect of the present invention, it is possible to provide an organic electroluminescent device that exhibits high luminous efficiency, is highly durable, and has excellent life characteristics.

FIG. 1 is a schematic cross-sectional view showing an example of a layered structure of an organic electroluminescence element according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of a laminate structure of an organic electroluminescence element according to one embodiment of the present invention (structure of element example 1).

The enamine compound according to one embodiment of the present invention will be described in detail below.
<Enamine Compound>

The compound contained in the layer of the organic electroluminescent device according to one embodiment of the present invention is an enamine compound represented by formula (1).

In the formula, Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group which may have a substituent, and Ar ¹ and Ar ² may form a ring. Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent, and Ar ³ and Ar ⁴ may form a ring.
^R1 represents an aryl group, an alkyl group, a triarylsilyl group, a trialkylsilyl group, an alkoxy group, or an amino group, each of which may have a substituent. ^R1 is a single bond, and may form a ring together with ^Ar3 or ^Ar4 .
The total number of benzene rings possessed by Ar ¹ to Ar ⁴ and R ¹ is preferably 7 or more. However, when R ¹ forms a ring together with Ar ³ or Ar ⁴ and a nitrogen atom is included in the ring-forming atoms, the total number of benzene rings is 4 or more.
The compound contained in the layer of the organic electroluminescent device according to one embodiment of the present invention is a compound represented by the following general formula (2).

Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group which may have a substituent, and Ar ¹ and Ar ² may form a ring. Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent, and Ar ³ and Ar ⁴ may form a ring.
^R2 represents an aryl group, an alkyl group, a triarylsilyl group, a trialkylsilyl group, or an alkoxy group, each of which may have a substituent. ^R2 is a single bond, and may form a ring together with ^Ar3 or ^Ar4 .
However, the total number of benzene rings possessed by Ar ¹ to Ar ⁴ and R ² is 7 or more. When R ² forms a ring together with Ar ³ or Ar ⁴ and a nitrogen atom is included in the ring-forming atoms, the total number of benzene rings is 4 or more.

The compound contained in the layer of the organic electroluminescent device according to one embodiment of the present invention is a compound represented by the following general formula (3).

Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group which may have a substituent, and Ar ¹ and Ar ² may form a ring. Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent.
^R3 represents an amino group which may have a substituent.

Hereinafter, the enamine compounds represented by formula (1), formula (2), and formula (3) may be referred to as enamine compound (1), enamine compound (2), and enamine compound (3), respectively.

The definitions of the substituents in the enamine compounds (1) to (3) and preferred specific examples thereof are as follows.
[Regarding Ar ¹ and Ar ² ]

Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group. Ar ¹ and Ar ² each independently may be substituted with one or more groups selected from a fluorine atom, a methyl group, and a phenyl group, and may form a ring together with Ar ¹ and Ar ² .
[Regarding ^Ar3 and ^Ar4 ]

Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent, and Ar ³ and Ar ⁴ may form a ring.

^Ar3 and ^Ar4 are preferably a phenyl group, a naphthyl group, a fluorenyl group, an anthranyl group, a phenanthrenyl group, or a carbazole group, each of which may be independently substituted with one or more groups selected from a fluorine atom, a methyl group, a phenyl group, and a carbazole group.
[Regarding ^R1 ]

^R1 represents an aryl group, an alkyl group, a triarylsilyl group, a trialkylsilyl group, an alkoxy group, or an amino group, each of which may have a substituent. ^R1 is a single bond, and may form a ring together with ^Ar3 or ^Ar4 .
The total number of benzene rings possessed by Ar ¹ to Ar ⁴ and R ¹ is preferably 7 or more. However, when R ¹ forms a ring together with Ar ³ or Ar ⁴ and a nitrogen atom is included in the ring-forming atoms, the total number of benzene rings is preferably 4 or more.

Examples of ^R1 include a phenyl group, a biphenyl group, a trimethylsilyl group, a triphenylsilyl group, etc. ^R1 may be substituted with one or more groups selected from a fluorine atom, a methyl group, a phenyl group, and a carbazole group.
[Regarding ^R2 ]

^R2 represents an aryl group, an alkyl group, a triarylsilyl group, a trialkylsilyl group, or an alkoxy group, each of which may have a substituent. ^R2 is a single bond, and may form a ring together with ^Ar3 or ^Ar4 .

Examples of ^R2 include a phenyl group, a biphenyl group, a trimethylsilyl group, a triphenylsilyl group, etc. ^R2 may be substituted with one or more groups selected from a fluorine atom, a methyl group, a phenyl group, and a carbazole group.
The total number of benzene rings possessed by Ar ¹ to Ar ⁴ and R ² is 7 or more. When R ² forms a ring together with Ar ³ or Ar ⁴ and a nitrogen atom is included in the ring-forming atoms, the total number of benzene rings is 4 or more.
[Regarding ^R3 ]

^R3 represents an amino group which may have a substituent.

[Specific examples of enamine compounds (1) to (3)]
Specific examples of the enamine compounds (1) to (3) are shown below, but the present invention is not limited thereto. In the structural formulae, Ph represents a phenyl group, Me represents a methyl group, and TMS represents a trimethylsilyl group.

The enamine compounds (1) to (3) according to one embodiment of the present invention can be produced by appropriately combining known reactions.
<Materials for organic electroluminescence devices>

The enamine compounds (1) to (3) are useful as materials for organic electroluminescent devices. The enamine compound (1) can be used, for example, as a hole transport material for organic electroluminescent devices. The material for organic electroluminescent devices containing the enamine compound (1) exhibits high luminous efficiency and long life characteristics, and can be used to produce organic electroluminescent devices that can be used for various purposes or in various environments.
<Organic electroluminescent device>

Hereinafter, an organic electroluminescent device having a layer containing enamine compounds (1) to (3) (hereinafter, sometimes simply referred to as an organic electroluminescent device) will be described.

The layer forming the organic electroluminescent device according to one embodiment of the present invention contains enamine compounds (1) to (3).

The configuration of the organic electroluminescent device is not particularly limited, but examples thereof include the following configurations (i) to (v).
(i): anode/light-emitting layer/cathode (ii): anode/hole-transport layer/light-emitting layer/cathode (iii): anode/light-emitting layer/electron-transport layer/cathode (iv): anode/hole-transport layer/light-emitting layer/electron-transport layer/cathode (v): anode/hole-injection layer/hole-transport layer/light-emitting layer/electron-transport layer/electron-injection layer/cathode

The enamine compound (1) may be contained in any of the above layers, but in terms of providing excellent light-emitting properties to the organic electroluminescent device, it is preferable that the enamine compound (1) is contained in one or more layers selected from the group consisting of the light-emitting layer and the layer between the light-emitting layer and the anode.

Therefore, in the case of the configurations shown in (i) to (v) above, it is preferable that the enamine compounds (1) to (3) are contained in one or more layers selected from the group consisting of the light-emitting layer, the hole-transport layer, and the hole-injection layer.

Hereinafter, the organic electroluminescent device according to one aspect of the present invention will be described in more detail with reference to FIG. 1, taking the above configuration (v) as an example.

The organic electroluminescent device shown in FIG. 1 has a so-called bottom emission type element configuration, but the organic electroluminescent device according to one aspect of the present invention is not limited to a bottom emission type element configuration. In other words, the organic electroluminescent device according to one aspect of the present invention may have other known element configurations, such as a top emission type.

Figure 1 is a schematic cross-sectional view showing an example of the layered structure of an organic electroluminescent device containing an enamine compound according to one embodiment of the present invention.

The organic electroluminescent device 100 comprises a substrate 1, an anode 2, a hole injection layer 3, a hole transport layer 4, an emitting layer 5, an electron transport layer 6, an electron injection layer 7, and a cathode 8, in this order. However, some of these layers may be omitted, or other layers may be added. For example, a hole blocking layer may be provided between the emitting layer 5 and the electron transport layer 6, or the hole injection layer 3 may be omitted and the hole transport layer 4 may be provided directly on the anode 2.

Alternatively, a single layer having the functions of the multiple layers, such as an electron injection/transport layer having both the functions of the electron injection layer and the electron transport layer in a single layer, may be provided instead of the multiple layers. Furthermore, for example, the single-layer hole transport layer 4 and the single-layer electron transport layer 6 may each be made up of multiple layers.
<Layer Containing Enamine Compounds (1) to (3)>

In the configuration example shown in FIG. 1, the organic electroluminescent device 100 contains enamine compounds (1) to (3) in one or more layers selected from the group consisting of the light-emitting layer 5, the hole transport layer 4, and the hole injection layer 3. In particular, it is preferable that the hole transport layer 4 contains the enamine compounds (1) to (3). The enamine compounds (1) to (3) may be contained in multiple layers of the organic electroluminescent device.

Hereinafter, as one of the preferred embodiments, an organic electroluminescent device 100 in which the hole transport layer 4 contains the enamine compounds (1) to (3) will be described.
[Substrate 1]

There are no particular limitations on the substrate 1, and examples include a glass plate, a quartz plate, a plastic plate, etc.

Examples of the substrate 1 include a glass plate, a quartz plate, a plastic plate, and a plastic film. Among these, a glass plate, a quartz plate, and a light-transmitting plastic film are preferred.

Examples of light-transmitting plastic films include films made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), etc.

In the case of a configuration in which light is extracted from the substrate 1 side, the substrate 1 is transparent to the wavelength of light.
[Anode 2]

An anode 2 is provided on the substrate 1 (on the hole injection layer 3 side).

Examples of the anode material include metals, alloys, electrically conductive compounds, and mixtures thereof, each having a large work function (e.g., 4 eV or more). Specific examples of the anode material include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO.

In the case of an organic electroluminescent device in which light is extracted through the anode, the anode is formed of a conductive transparent material that is transparent or substantially transparent to the emitted light.
[Hole injection layer 3, hole transport layer 4]

Between the anode 2 and the light-emitting layer 5, a hole injection layer 3 and a hole transport layer 4 are provided in this order from the anode 2 side.

The hole injection layer and hole transport layer have the function of transporting holes injected from the anode to the light-emitting layer, and by interposing this hole injection layer and hole transport layer between the anode and the light-emitting layer, more holes are injected into the light-emitting layer with a lower electric field.

The hole injection layer and the hole transport layer also function as electron barrier layers. That is, the electrons injected from the cathode and transported from the electron injection layer and/or the electron transport layer to the light emitting layer are prevented from leaking to the hole injection layer and/or the hole transport layer due to the electron barrier present at the interface between the light emitting layer and the hole injection layer and/or the hole transport layer. As a result, the electrons are accumulated at the interface within the light emitting layer, which brings about effects such as improved light emitting efficiency, and an organic electroluminescent element with excellent light emitting performance is obtained.

The material for the hole injection layer and the hole transport layer has at least one of hole injection property, hole transport property, and electron barrier property.
As described above, the hole transport layer preferably contains the enamine compounds (1) to (3). The hole transport layer may further contain one or more types selected from conventionally known hole transport materials in addition to the enamine compounds (1) to (3).

In addition, when the enamine compounds (1) to (3) are not contained in the hole transport layer but are contained in another layer, one or more types selected from conventionally known hole transport materials can be used as the hole transport material constituting the hole transport layer.

Specific examples of conventionally known materials for the hole injection layer and hole transport layer include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers (particularly thiophene oligomers), porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds.

Among these, porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds are preferred because they produce good performance in organic electroluminescent devices, and aromatic tertiary amine compounds are particularly preferred.

Specific examples of aromatic tertiary amine compounds and styrylamine compounds include N,N,N',N'-tetraphenyl-4,4'-diaminophenyl, N,N'-diphenyl-N,N'-bis(m-tolyl)-[1,1'-biphenyl]-4,4'-diamine (TPD), 2,2-bis(4-di-p-tolylaminophenyl)propane, 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane, N,N,N',N'-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane, bis(4-dimethylamino-2-methylphenyl)phenylmethane, bis(4-di-p-tolylaminophenyl)phenylmethane, N,N'-diphenyl-N,N'-di (4-methoxyphenyl)-4,4'-diaminobiphenyl, N,N,N',N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis(diphenylamino)quadriphenyl, N,N,N-tri(p-tolyl)amine, 4-(di-p-tolylamino)-4'-[4-(di-p-tolylamino)styryl]stilbene, 4-N,N-diphenylamino-(2-diphenylvinyl)benzene, 3-methoxy-4'-N,N-diphenylaminostilbene, N-phenylcarbazole, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD), 4,4',4''-tris[N-(m-tolyl)-N-phenylamino]triphenylamine (MTDATA), etc.

Inorganic compounds such as p-type Si and p-type SiC can also be used as examples of materials for the hole injection layer and hole transport layer.

The hole injection layer and the hole transport layer may have a single structure made of one or more materials, or may have a laminate structure made of a plurality of layers having the same composition or different compositions.
[Light-emitting layer 5]

Between the hole transport layer 4 and the electron transport layer 6, a light emitting layer 5 is provided.

Materials for the light-emitting layer include phosphorescent materials, fluorescent materials, and thermally activated delayed fluorescent materials. In the light-emitting layer, electron-hole pairs recombine, resulting in light emission.

The light-emitting layer may consist of a single small molecule material or a single polymeric material, but more commonly consists of a host material doped with a guest compound. Emission comes primarily from the dopant and can be of any color.

Examples of host materials include compounds having a biphenylyl group, a fluorenyl group, a triphenylsilyl group, a carbazole group, a pyrenyl group, and an anthryl group. More specifically, examples of the compound include DPVBi (4,4'-bis(2,2-diphenylvinyl)-1,1'-biphenyl), BCzVBi (4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl), TBADN (2-tertiarybutyl-9,10-di(2-naphthyl)anthracene), ADN (9,10-di(2-naphthyl)anthracene), CBP (4,4'-bis(carbazol-9-yl)biphenyl), CDBP (4,4'-bis(carbazol-9-yl)-2,2'-dimethylbiphenyl), 2-(9-phenylcarbazol-3-yl)-9-[4-(4-phenylphenylquinazolin-2-yl)carbazole, 9,10-bis(biphenyl)anthracene, and the like.

Examples of fluorescent dopants include anthracene, pyrene, tetracene, xanthene, perylene, rubrene, coumarin, rhodamine, quinacridone, dicyanomethylenepyran compounds, thiopyran compounds, polymethine compounds, pyrylium, thiapyrylium compounds, fluorene derivatives, periflanthene derivatives, indenoperylene derivatives, bis(azinyl)amine boron compounds, bis(azinyl)methane compounds, carbostyril compounds, boron compounds, and cyclic amine compounds. The fluorescent dopant may be a combination of two or more selected from these.

Examples of phosphorescent dopants include organometallic complexes of transition metals such as iridium, platinum, palladium, and osmium.

Specific examples of fluorescent and phosphorescent dopants include Alq3 (tris(8-hydroxyquinoline)aluminum), DPAVBi (4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl), perylene, bis[2-(4-n-hexylphenyl)quinoline](acetylacetonate)iridium(III), Ir(PPy)3 (tris(2-phenylpyridine)iridium(III)), and FIrPic (bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III))).

The light-emitting material is not limited to being contained only in the light-emitting layer. For example, the light-emitting material may be contained in a layer adjacent to the light-emitting layer (hole transport layer 4 or electron transport layer 6). This can further increase the light-emitting efficiency of the organic electroluminescent element.

The light-emitting layer may have a single layer structure made of one or more materials, or may have a laminate structure made of multiple layers of the same composition or different compositions.
[Electron transport layer 6]

An electron transport layer 6 is provided between the light-emitting layer 5 and the electron injection layer 7.

The electron transport layer has the function of transporting electrons injected from the cathode to the light-emitting layer. By interposing the electron transport layer between the cathode and the light-emitting layer, electrons are injected into the light-emitting layer at a lower electric field.

The materials for the electron injection layer and the electron transport layer may be either organic or inorganic.
Examples of conventionally known electron transporting materials include alkali metal complexes, alkaline earth metal complexes, and earth metal complexes.

Examples of alkali metal complexes, alkaline earth metal complexes, and earth metal complexes include 8-hydroxyquinolinato lithium (Liq), bis(8-hydroxyquinolinato) zinc, bis(8-hydroxyquinolinato) copper, bis(8-hydroxyquinolinato) manganese, tris(8-hydroxyquinolinato) aluminum, tris(2-methyl-8-hydroxyquinolinato) aluminum, and tris(8-hydroxyquinolinato) gallium. bis(10-hydroxybenzo[h]quinolinato) beryllium, bis(10-hydroxybenzo[h]quinolinato) zinc, bis(2-methyl-8-quinolinato) chlorogallium, bis(2-methyl-8-quinolinato) (o-cresolate) gallium, bis(2-methyl-8-quinolinato)-1-naphtholato aluminum, bis(2-methyl-8-quinolinato)-2-naphtholato gallium, etc.

The electron transport layer may be a single layer structure made of one or more materials, or a laminate structure made of multiple layers of the same or different compositions.

In the organic electroluminescent device according to one aspect of the present invention, an electron injection layer may be provided for the purpose of improving electron injection properties and improving device characteristics (e.g., luminous efficiency, low-voltage driving, or high durability).
[Electron injection layer 7]

Between the electron transport layer 6 and the cathode 8, an electron injection layer 7 is provided. The electron injection layer has the function of transporting electrons injected from the cathode to the light-emitting layer. By interposing the electron injection layer between the cathode and the light-emitting layer, electrons are injected into the light-emitting layer at a lower electric field.

Materials for the electron injection layer include organic compounds such as fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylene tetracarboxylic acid, fluorenylidene methane, anthraquinodimethane, and anthrone.

Examples of materials for the electron injection layer include inorganic compounds such as various oxides, fluorides, nitrides, and oxynitrides, such as _SiO2 , AlO, SiN, SiON, AlON, GeO, LiO, LiON, TiO, TiON, TaO, TaON, TaN, LiF, C, and Yb.
[Cathode 8]

A cathode 8 is provided on the electron injection layer 7. In the case of an organic electroluminescence element in which only the emitted light that passes through the anode is extracted, the cathode can be made of any conductive material.

Cathode materials include, for example, metals with a low work function (hereinafter also referred to as electron-injecting metals), alloys, electrically conductive compounds, and mixtures thereof. Here, a metal with a low work function is, for example, a metal with a work function of 4 eV or less.

Specific examples of cathode materials include sodium, sodium-potassium alloys, magnesium, lithium, magnesium/copper mixtures, magnesium/silver mixtures, magnesium/aluminum mixtures, magnesium/indium mixtures, aluminum/aluminum oxide (Al ₂ O ₃ ) mixtures, indium, lithium/aluminum mixtures, rare earth metals, and the like.

Among these, from the viewpoints of electron injectability and durability against oxidation, etc., preferred are mixtures of an electron injecting metal and a second metal which has a larger and more stable work function than the electron injecting metal, such as a magnesium/silver mixture, a magnesium/aluminum mixture, a magnesium/indium mixture, an aluminum/aluminum oxide ( _Al2O3 ) mixture, and _a lithium/aluminum mixture.
[Method of forming each layer]

Each layer, except for the electrodes (anode, cathode) described above, can be formed by thinning using known methods such as vacuum deposition, spin coating, casting, and the Langmuir-Blodgett (LB) method. The material for each layer may be used alone or, if necessary, together with a binder resin or other material or solvent.

There are no particular limitations on the thickness of each layer formed in this way and it can be selected appropriately depending on the situation, but it is usually in the range of 5 nm to 5 μm.

The anode and cathode can be formed by forming a thin film of the electrode material by a method such as vapor deposition or sputtering. A pattern may be formed through a mask of the desired shape during vapor deposition or sputtering, or a pattern of the desired shape may be formed by photolithography after forming a thin film by vapor deposition or sputtering.

The thickness of the anode and cathode is preferably 1 μm or less, and more preferably 10 nm or more and 200 nm or less.

Organic electroluminescent devices can be used as a type of lamp for illumination or exposure light sources, as a projection device that projects images onto a screen, or as a display device (display) that allows still or moving images to be viewed directly.

When using organic electroluminescent elements as a display device for playing moving images, the driving method may be a simple matrix (passive matrix) method or an active matrix method. In addition, by using two or more types of organic electroluminescent elements that emit different colors of light, it is possible to create a full-color display device.

When used as a hole transport layer, the enamine compounds (1) to (3) can provide an organic electroluminescent device that has significantly superior long life characteristics compared to conventionally known enamine compounds.

The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited to these examples.
[ ¹ H-NMR measurement]

Gemini 200 (Varian) was used for ¹ H-NMR measurement. ¹ H-NMR was measured using deuterated chloroform (CDCl ₃ ) as a measurement solvent and tetramethylsilane (TMS) as an internal standard substance. Commercially available reagents were used.
[DSC Measurement (glass transition temperature, crystallization temperature, melting point)]

The glass transition temperature, crystallization temperature and melting point were measured using a DSC7020 (product name, manufactured by Hitachi High-Tech Science Corporation).

The DSC measurement conditions are as follows. The measurement was performed under a nitrogen atmosphere (flow rate 50 ml/min). The first cooling and second heating were performed in this order, and the glass transition temperature, crystallization temperature, and melting point during the second heating were taken as the glass transition temperature, crystallization temperature, and melting point of the sample, respectively.
Sample amount: 5-10 mg
Measurement conditions:
<First Heating>
Heating rate: 15° C./min
Measurement temperature range: 30℃ to 360℃
<First cooling>
Rapid cooling with dry ice (second heating)
Heating rate: 5° C./min
Measurement temperature range: 30℃ to 360℃
[Measurement of luminescence characteristics]

The light-emitting characteristics of the organic electroluminescent device were evaluated by applying a direct current to the fabricated device in a 25°C environment using a luminance meter BM-9 (product name, manufactured by Topcon Technohouse).

Synthesis Example-1 (Compound-1)

A 100 mL two-necked reactor equipped with a reflux condenser was flame dried and argon substituted, and bromotriphenylethylene (5 mmol, 1.68 g) (Tokyo Chemical Industry Co., Ltd.), bis(4-biphenyl)amine (5.5 mmol, 1.77 g), sodium t-butoxide (NaO ^t Bu) (6.5 mmol, 620 mg) (Fujifilm Wako Pure Chemical Industries, Ltd.), palladium acetate (Pd(OAc) ₂ ) (0.05 mmol, 11.2 mg) (Fujifilm Wako Pure Chemical Industries, Ltd.), tri-t-butylphosphine (P ^t Bu ₃ ) (0.2 mmol, 40.4 mg) (Aldrich), and xylene (dehydrated) (15 ml) were added thereto in that order, and the mixture was heated to 120° C. and stirred for 3 hours. The reaction solution was transferred to a separatory funnel, 50 mL of water was added, and the mixture was extracted three times with diethyl ether (30 mL). The organic layer was washed with saturated saline and dried over NaSO ₄ , and the solvent was then distilled off under reduced pressure. The resulting viscous solid was purified several times by silica gel column chromatography (hexane/Et ₂ O = 100:0 to 90:10 gradient) to obtain 1.85 g of the target product in a yield of 64%.

¹ H-NMR (400 MHz, CDCl ₃ ) δ: 7.50 (d, J = 7.4, 4H), 7.38 (t, J = 7.4, 6H), 7.22-7.30 ( m, 6H), 7.04-7.13 (m, 12H), 6.97 (s, 5H).
^13C -NMR (100MHz, _CDCl3 ) δ: 146.0, 143.2, 142.7, 142.0, 140.9, 138.1, 137.8, 134, 2, 131.3, 129.1, 128. 7,128.0,127,9,127.9,127.8,127.5,127.2,126.8,126.7,126.6,126.5,122.5.

Synthesis Example 2 (Compound 4)

By carrying out the same procedure as in Example 1, except that diarylamine was replaced with N-(4-(9H-carbazol-9-yl)phenyl)-[1,1'-biphenyl]-4-amine (5.5 mmol, 2.3 g), 2.1 g of the target product was obtained in a yield of 64%.

¹ H-NMR (400 MHz, CDCl ₃ ) δ: 8.12 (d, J = 7.4, 2H), 7.51 (d,
J=7.4, 2H), 7.03-7.43 (m, 32H).
^13C -NMR (100MHz, _CDCl3 ) δ: 146.6, 145.2, 142.5, 142.0, 141.2, 140.6, 137.9, 137, 7, 134.4, 131.4, 131.3, 131.1 , 129.3, 128.8, 128. 1,128.0, 127.7, 127.5, 127.4, 126.9, 126.8, 126.7, 126.6, 125.8, 123.7, 123.1, 122.2, 120.3, 119.7, 109.9.

Synthesis Example 3 (Compound 2)

By carrying out the same procedure as in Example 1, except that diarylamine was replaced with N-([1,1'-biphenyl]-4-yl)-4'-(9H-carbazole-9-yl)-[1,1'-biphenyl]-4-amine (5.5 mmol, 2.7 g), 2.2 g of the target product was obtained in a yield of 57%.

¹ H-NMR (400 MHz, CDCl ₃ ) δ: 8.13 (d, J = 7.4, 2H), 7.71 (d, J = 7.4, 2H), 7.57 (d, J = 7.4, 2H), 7. 51 (d, J=7.4, 2H), 7.07-7.44 (m, 27H), 7.01 (s, 5H).
^13C -NMR (100MHz, _CDCl3 ) δ: 146.3, 145.9, 143.1, 142.6, 141.9, 140.9, 140.9, 140, 8, 139.9, 138.0, 137.9, 136.2 , 134, 4, 133.1, 131.4, 131.3, 129.2, 128. 8,128.0,127.9,127.9,127.8,127.6,127.3,127.3,127.2,126.8,126.7,126.6,126.0, 123.4, 122.6, 122.5, 120.4, 120.0, 109.9.

Synthesis Example 4 (Compound 44)

By performing the same procedure as in Example 1 except that the reaction scale was doubled and diarylamine was replaced with 4-(9H-carbazole-9-yl)-N-phenylaniline (11 mmol, 3.7 g), 4.5 g of the target product was obtained in 77% yield.

¹ H-NMR (400 MHz, CDCl ₃ ) δ: 8.13 (d, J = 7.4, 2H), 7.37-7.42 (m, 4H), 7.06-7.28 (m, 25H), 6.83(t, 1H).
^13C -NMR (100MHz, _CDCl3 ) δ: 146.8, 145.9, 143.3, 142.6, 142.1, 141.2, 138.0, 137.4, 131.4, 131.4, 131.0, 129.3 ,128.8,1 28.0, 128.0, 127.9, 127.6, 127.4, 126.9, 126.6, 125.8, 123.1, 122.2, 121.9, 120.3, 119. 7,109.9.

Synthesis Example 5 (Compound 3)

By performing the same procedure as in Example 1 except that the reaction scale was doubled and diarylamine was replaced with 4-(9H-carbazole-9-yl)-N-phenyl-[1,1'-biphenyl]-4-amine (11 mmol, 4.5 g), 2.4 g of the target product was obtained in a yield of 36%.

¹ H-NMR (400 MHz, CDCl ₃ ) δ: 8.14 (d, J = 7.4, 2H), 7.68 (d, J = 7.4, 2H), 7.55 (d, J = 7.4, 2H), 6.98-7.44 (m, 29H), 6.80 (t, J=7.4, 1H).
^13C -NMR (100MHz, _CDCl3 ) δ: 146.6, 146.5, 143.1, 142.7, 142.1, 141.0, 140.0, 138.1, 137.7, 136.2, 133.0, 131.4 , 129.2, 128. 7,128.0,127.9,127.8,127.5,127.3,127.2,126.8,126.6,126.0,123.4,122.6,122.4, 122.0, 109.9.

Synthesis Example 6 (Compound 75)

By carrying out the same operations as in Example 1, except that the bromide compound was changed to 2-bromo-1,1'-diphenylpropene and the scale was changed to that equivalent to 2-bromo-1,1'-diphenylpropene (1 mmol, 0.27 g), 0.43 g of the target product was obtained in a yield of 84%.

¹ H-NMR (600 MHz, CDCl ₃ ) δ: 7.55 (d, J=8.2, 4H), 7.26-7.44 (m, 15H), 7.08 (d, J=8. 2,4H), 6.95 (s, 5H), 2.16 (s, 3H).
^13C -NMR (150MHz, _CDCl3 ) δ: 145.5, 142.0, 141.6, 140.9, 138.3, 134.1, 129.9, 128.7, 128.6, 128.1, 127.6, 127.3 , 126.8, 126.6, 126.6, 126.4, 121.9, 18.8.

Synthesis Example-7 (Compound-8)

A 100 mL two-necked reactor equipped with a reflux condenser was flame dried and purged with argon, and 1,1-dibromo-2,2-diphenylethylene (5 mmol, 1.69 g), diphenylamine (5.5 mmol, 0.93 g), sodium t-butoxide (NaO ^t Bu) (11.5 mmol, 1.10 g) (FUJIFILM Wako Pure Chemical Industries, Ltd.), palladium acetate (Pd(OAc) ₂ ) (0.25 mmol, 56.0 mg) (FUJIFILM Wako Pure Chemical Industries, Ltd.), tri-t-butylphosphine (P ^t Bu ₃ ) (1 mmol, 202.0 mg) (Aldrich), and xylene (dehydrated) (15 ml) were added thereto in that order, and the mixture was heated to 110° C. and stirred for 2 hours. The reaction solution was transferred to a separatory funnel, 50 mL of water was added, and the mixture was extracted three times with diethyl ether (30 mL). The organic layer was washed with saturated saline and dried over NaSO ₄ , and the solvent was then distilled off under reduced pressure. The resulting viscous solid was purified by silica gel column chromatography (hexane/Et ₂ O = 100:0 to 90:10 gradient), and then recrystallized from methanol to obtain 535 mg of the target product in a 31% yield.

¹ H-NMR (400 MHz, CDCl ₃ ) δ: 7.47-7.54 (m, 2H), 7.37-7.45 (m, 3H), 7.31-7.36 (m, 2H), 7.15-7.23 ( m, 3H), 7.03-7. 15 (m, 3H), 6.92 (d, J = 7.4, 1H), 6.83 (t, J = 7.4, 1H), 6.73-6.81 (m, 3H), 6.68 (d, J=7.4, 1H)
^13C -NMR (100MHz, _CDCl3 ) δ: 157.6, 143.2, 139.4, 138.2, 132.2, 131.2, 130.5, 128.9, 128.4, 128.4, 128.1, 128.0 , 127, 6, 124.6, 121.8, 121.8, 119.7, 119.0, 107.2.

Next, the element evaluation will be described.
The structural formulas and abbreviations of the compounds used in the element evaluation are shown below.

<Element Example 1> (See FIG. 2)
(Preparation of Substrate 1 and Anode 2)
A glass substrate with an indium tin oxide (ITO) transparent electrode, on which a 2 mm wide ITO film (thickness: 110 nm) was patterned in stripes, was prepared as a substrate having an anode on its surface. The substrate was then washed with isopropyl alcohol and then subjected to surface treatment by ozone ultraviolet cleaning.

(Preparation for vacuum deposition)
After cleaning and surface treatment, each layer was deposited by vacuum deposition on the substrate by vacuum deposition, so that each layer was laminated.
First, the glass substrate was placed in a vacuum deposition chamber, and the pressure was reduced to 1.0×10 ⁻⁴ Pa. Then, each layer was prepared according to the film formation conditions in the following order.

(Fabrication of Hole Injection Layer 3)
The sublimation-purified HIL was deposited at a rate of 0.15 nm/sec to a thickness of 55 nm to prepare a hole injection layer.

(Preparation of Charge Generation Layer 9)
The sublimation-purified HAT was formed into a film having a thickness of 5 nm at a rate of 0.05 nm/sec to prepare a charge generating layer.

(Preparation of First Hole Transport Layer 41)
HTL-1 was deposited at a rate of 0.15 nm/sec to a thickness of 15 nm to form a first hole transport layer.

(Preparation of second hole transport layer 42)
The compound 1 synthesized in Synthesis Example 1 was formed into a film having a thickness of 50 nm at a rate of 0.15 nm/sec to prepare a second hole transport layer.

(Preparation of Light-Emitting Layer 5)
The light-emitting layer was prepared by depositing EML-1 and EML-2 at a ratio of 95:5 (mass ratio) to a thickness of 35 nm at a deposition rate of 0.18 nm/sec.

(Preparation of Electron Transport Layer 6)
An electron transport layer was prepared by depositing a film of ETL and Liq at a ratio of 50:50 (mass ratio) to a thickness of 30 nm at a deposition rate of 0.15 nm/sec.

(Preparation of Cathode 8)
Finally, a metal mask was placed perpendicular to the ITO stripes on the substrate, and a cathode was formed. The cathode was formed of a two-layer structure in which silver/magnesium (mass ratio 1/10) and silver were deposited in this order to thicknesses of 80 nm and 20 nm, respectively. The deposition rate of silver/magnesium was 0.5 nm/sec, and the deposition rate of silver was 0.2 nm/sec.

In this manner, an organic electroluminescent device 100 having a light-emitting area ^{of 4} mm2 was produced as shown in Fig. 2. The thickness of each film was measured using a stylus film thickness meter (DEKTAK, manufactured by Bruker).

The device was then sealed in a nitrogen atmosphere glove box with oxygen and moisture concentrations of 1 ppm or less. The glass sealing cap and the film-formed substrate (device) were sealed using bisphenol F epoxy resin (manufactured by Nagase ChemteX Corporation).

A direct current was applied to the organic electroluminescent device prepared as described above, and the light-emitting characteristics were evaluated using a luminance meter (product name: BM-9, manufactured by Topcon Technohouse). As the light-emitting characteristics, the driving voltage (V) when a current density of 10 mA/ ^cm2 was applied was measured. The measurement results obtained are shown in Table 1.

<Element Example 2>
An organic electroluminescence device was produced and evaluated in the same manner as in Element Example 1, except that Compound 4 prepared in Synthesis Example 2 was used instead of Compound 1 prepared in Synthesis Example 1 in Element Example 1. The measurement results obtained are shown in Table 1.

<Element Example 3>
An organic electroluminescence device was produced and evaluated in the same manner as in Element Example 1, except that Compound 2 produced in Synthesis Example 3 was used instead of Compound 1 produced in Synthesis Example 1 in Element Example 1. The measurement results obtained are shown in Table 1.

<Element Example 4>
An organic electroluminescence device was produced and evaluated in the same manner as in Element Example 1, except that Compound 44 prepared in Synthesis Example 4 was used instead of Compound 1 prepared in Synthesis Example 1. The measurement results obtained are shown in Table 1.

<Reference element example 1>
An organic electroluminescence device was prepared and evaluated in the same manner as in Element Example 1, except that the following compound X (compound-16) described in JP-A-2006-269834 was used instead of compound-1 prepared in Synthesis Example 1. The obtained measurement results are shown in Table 1.

The enamine compound (1) according to one embodiment of the present invention can provide an organic electroluminescent device with excellent durability by using the compound.

The enamine compound (1) according to one embodiment of the present invention can be used as a hole transport material for organic electroluminescence elements, which contributes to the production of organic electroluminescence elements with excellent durability. Furthermore, the enamine compound (1) can provide an organic electroluminescence element with low power consumption and high luminous efficiency.

REFERENCE SIGNS LIST 100 Organic electroluminescent element 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 41 First hole transport layer 42 Second hole transport layer 5 Light-emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode 9 Charge generation layer

Claims (4)

An organic electroluminescent device having a layer containing a compound represented by the following general formula (1):

Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group which may have a substituent, and Ar ¹ and Ar ² may form a ring. Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent, and Ar ³ and Ar ⁴ do not form a ring.
^R1 represents an aryl group, an alkyl group, a triarylsilyl group, a trialkylsilyl group, an alkoxy group, or an amino group, each of which may have a substituent. ^R1 is a single bond, and may form a ring together with ^Ar3 or ^Ar4 . The organic electroluminescent device according to claim 1, wherein the total number of benzene rings contained in Ar ¹ to Ar ⁴ and R ¹ is 7 or more. However, when R ¹ forms a ring together with Ar ³ or Ar ⁴ and a nitrogen atom is included in the ring-forming atoms, the total number of benzene rings is 4 or more. A compound represented by the following general formula (2):

Ar ¹ and Ar ² each independently represent a phenyl group, a naphthyl group, or a biphenyl group which may have a substituent, and Ar ¹ and Ar ² may form a ring. Ar ³ and Ar ⁴ each independently represent an aryl group or a heteroaryl group which may have a substituent, and Ar ³ and Ar ⁴ do not form a ring.
^R2 represents an aryl group, an alkyl group, a triarylsilyl group, a trialkylsilyl group, or an alkoxy group, each of which may have a substituent. ^R2 is a single bond, and may form a ring together with ^Ar3 or ^Ar4 .
However, the total number of benzene rings possessed by Ar ¹ to Ar ⁴ and R ² is 7 or more. When R ² forms a ring together with Ar ³ or Ar ⁴ and a nitrogen atom is included in the ring-forming atoms, the total number of benzene rings is 4 or more. A material for an organic electroluminescent device, comprising the compound according to claim 3 .

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