JP2001271063A - Material for organic electroluminescent device and organic electroluminescent device using the same material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent device having high emission luminance and luminous efficiency, and excellent in an emission lifetime. SOLUTION: A material for the fluorescence-emitting organic substance is composed of a compound represented by general formula 1, and embodied examples thereof are exemplified by general formulae 2 and 3.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence (EL) device material used for a flat light source and a display, and a device using the same.

[0001]

2. Description of the Related Art An EL element using an organic material is expected to be used as an inexpensive large-area solid-color display element of a solid light emitting type, and many developments have been made. Generally, an EL element includes a light-emitting layer and a pair of opposed electrodes sandwiching the light-emitting layer.

[0002] Light emission occurs when an electric field is applied between both electrodes.
Electrons are injected from the cathode side and holes are injected from the anode side. These electrons recombine with holes in the light emitting layer, and emit energy as light when the energy level returns from the conduction band to the valence band. It is a phenomenon.

[0003] Conventional organic EL devices have a higher driving voltage and lower luminous brightness and luminous efficiency than inorganic EL devices.
In addition, the characteristic deterioration was remarkable, and it had not been put to practical use.

In recent years, an organic EL device in which a thin film containing an organic compound having high fluorescence quantum efficiency which emits light at a low voltage of 10 V or less has been reported and attracted attention (Applied Physics Letters, vol. , 913, 1987).

In this method, high-luminance green light emission is obtained by using a metal chelate complex for a phosphor layer and an amine compound for a hole injection layer.
0 (cd / m ² ), maximum luminous efficiency is 1.5 (lm / W)
To achieve performance close to the practical range. However, the organic EL devices up to now have improved luminous intensity in green due to the improved configuration, but the initial luminous efficiency of these organic EL devices is not yet sufficient, and furthermore, when light is emitted continuously. Degradation was remarkable, and there was a serious problem in practical use.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic EL device having high luminous brightness and luminous efficiency and excellent luminous life.

[0007]

As a result of intensive studies by the present inventors, the compound represented by the general formula [1] or [2] was added to at least one layer of an organic EL device material, a light emitting layer, and a light emitting layer between a cathode and a light emitting layer. The present inventors have found that the organic EL device used in the electron transport zone has excellent light emission luminance, light emission efficiency, and light emission lifetime, and have accomplished the present invention.

That is, the present invention is a material for an organic electroluminescence device comprising a compound represented by the following general formula [1] or general formula [2]. General formula [1]

[0009]

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[Wherein R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aromatic heterocyclic group. . R ^{3 to} R ⁶ each independently represent a hydrogen atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group. It represents an oxy group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted aromatic heterocyclic oxy group. However, R ^{3 to} R ⁶ may be bonded together by adjacent substituents to be integrated. M represents a divalent to tetravalent metal, and n represents an integer of 1 to 4. General formula [2]

[0011]

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[In the formula, R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aromatic heterocyclic group. . R ^{3 to} R ⁶ each independently represent a hydrogen atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group. It represents an oxy group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted aromatic heterocyclic oxy group. However, R ^{3 to} R ⁶ may be bonded together by adjacent substituents to be integrated. Ar each independently represents a substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic group. M represents a divalent to tetravalent metal, and m represents an integer of 1 to 3. Further, the present invention is a light-emitting material for an organic electroluminescence device, comprising the above-mentioned organic electroluminescence device material and a doping material.

Further, the present invention relates to an organic electroluminescent device in which an organic compound thin film including a light emitting layer is formed between a pair of electrodes, wherein at least one layer is a layer containing the above organic electroluminescent device material. .

Further, the present invention relates to an organic electroluminescence device in which a plurality of organic compound thin films including a light emitting layer are formed between a pair of electrodes, wherein the light emitting layer is a layer containing the above organic electroluminescent device material. Element.

Further, the present invention relates to an organic electroluminescent device having a plurality of organic compound thin films including a light emitting layer formed between a pair of electrodes, wherein at least one layer between the cathode and the light emitting layer is formed of the organic electroluminescent device material. Is an organic electroluminescence element which is a layer containing

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the compound represented by the general formula [1] or [2], R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group. Or a substituted or unsubstituted aromatic heterocyclic group. R ^{3 to} R ⁶ each independently represent a hydrogen atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group. An oxy group, a substituted or unsubstituted aromatic heterocyclic group,
Or a substituted or unsubstituted aromatic heterocyclic oxy group. However, R ^{3 to} R ⁶ may be bonded together by adjacent substituents to form an integral group, and Ar is independently a substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic ring. Represents a group. M represents a divalent to tetravalent metal, n represents an integer of 1 to 4, and m represents an integer of 1 to 3.

Specific examples of the halogen atom of R ^{3 to} R ⁶ include chlorine, bromine, iodine and fluorine.

Specific examples of the alkyl group for R ^{1 to} R ⁶ include:
Methyl group, ethyl group, propyl group, butyl group, sec-
Butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, trichloromethyl group, benzyl group, α, α-dimethylbenzyl group and the like. Specific examples of the cycloalkyl group include There are a cyclopentane group, a cyclohexane group and the like.

Specific examples of the alkoxy group for R ^{3 to} R ⁶ include a methoxy group, an ethoxy group, an n-butoxy group,
t-butoxy group, trichloromethoxy group, trifluoroethoxy group, pentafluoropropoxy group, 2,2
3,3-tetrafluoropropoxy group, 1,1,1,
3,3,3-hexafluoro-2-propoxy group, 6-
And a (perfluoroethyl) hexyloxy group.

The aryl groups represented by R ^{1 to} R ⁶ and Ar include a monocyclic group and a condensed polycyclic group. A phenyl group is a monocyclic group, and a thionyl group, a thiophenyl group, a furanyl group is a condensed polycyclic group. Group, pyrrolyl group, imidazolyl group, pyrazolyl group, pyridyl group, pyrazinyl group, pyrimidinyl group,
Examples include a pyridazinyl group, an oxazolyl group, a thiazolyl group, an oxadiazolyl group, a thiadiazolyl group, an imidadiazolyl group, a naphthyl group, an anthryl group, a phenanthryl group, a fluorenyl group and a pyrenyl group.

Examples of the aromatic heterocyclic group represented by R ^{1 to} R ⁶ and Ar include an indole group, a purine group, a quinoline group, an isoquinoline group, a sinoline group, a quinoxaline group, a benzoquinoline group, a fluorenone group, a carbazole group, an oxazole group, Oxadiazole group, thiazole group, thiadiazole group, triazole group, imidazole group, benzoxazole group, benzothiazole group, benzotriazole group, benzimidazole group, bisbenzoxazole group, bisbenzothiazole group, bisbenzimidazole group, anthrone group , Dibenzofuran, dibenzothiophene, anthraquinone, acridone, phenothiazine, pyrrolidine, dioxane, morpholine and the like.

The aryl of the aryloxy group represented by R ^{3 to} R ⁶ and Ar represents the above aryl group, and the aromatic heterocyclic ring of the aromatic heterocyclic oxy group represents the above aromatic heterocyclic group.

Specific examples of the amino group of R ^{3 to} R ⁶ include an amino group, a bis (acetoxymethyl) amino group, a bis (acetoxyethyl) amino group and a bisacetoxypropyl)
Examples include an amino group, a bis (acetoxybutyl) amino group, and specific examples of the alkylamino group include an ethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, a benzylphenylamino group, a dibenzylamino group, and the like. Specific examples of the arylamino group include a phenylamino group, a (3-methylphenyl) amino group,
(4-methylphenyl) amino group and the like. Specific examples of the phenylamino group include phenylamino group, phenylmethylamino group, diphenylamino group, ditolylamino group, dibiphenylamino group, and di (4-methylbiphenyl) amino. Group, di (3-methylphenyl) amino group, di (4-methylphenyl) amino group, naphthylphenylamino group, dinaphthylamino group, dianthrylamino group,
A bis [4- (α, α-dimethylbenzyl) phenyl] amino group and the like.

In addition, adjacent groups R ^{3 to} R ⁶ may be bonded to each other to form a saturated or unsaturated ring such as a phenyl ring, a naphthyl ring, an anthryl ring, a pyrenyl ring, a carbazole ring, a benzopyranyl ring, a cyclohexyl ring. May be formed.

In the general formula [1] or [2], M represents beryllium, zinc, cadmium, magnesium, calcium, cobalt, iron, copper, nickel, strontium, scandium, aluminum, gallium, indium or yttrium. However, it is not limited to these. n and m depend on the valence of the metal atom. n is 2 for a divalent metal, 3 for a trivalent metal, and 4 for a tetravalent metal. m is 1 for a divalent metal, 2 for a trivalent metal, and 3 for a tetravalent metal.

An example of a method for synthesizing the compound represented by the general formula [1] or [2] of the present invention is shown below. The metal complex represented by the general formula [1] or [2] is synthesized by a complex formation reaction between a corresponding metal compound and a compound represented by the following general formula [3]. General formula [3]

[0027]

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[In the formula, R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aromatic heterocyclic group. . R ^{3 to} R ⁶ each independently represent a hydrogen atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group. It represents an oxy group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted aromatic heterocyclic oxy group. However, R ^{3 to} R ⁶ may be bonded together by adjacent substituents to be integrated. The method for synthesizing the compound (3) of the present invention is illustrated in the reaction formula [1]. Reaction formula [1]

[0029]

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Examples of the metal compound corresponding to the compound represented by the general formula [1] or [2] include halides such as chlorides and bromides of M, sulfates, nitrates, metal alkoxides, and partially acetylacetonate. And a metal compound substituted with an organic ligand compound as described above. The metal alkoxide is preferred as the metal compound from the viewpoint of the reactivity of the synthesis and the safety in operation, but is not limited thereto.

Solvents used in the synthesis include methanol, ethanol, isopropyl alcohol, ethyl acetate, acetonitrile, 1,4-dioxane, tetrahydrofuran,
It is selected from benzene, toluene, xylene, n-hexane, dimethylformamide, quinoline, sulfolane, water and the like. The reaction temperature is determined by the rate of ligand metal complex formation and is between 0 ° C and 250 ° C, and even between 20 ° C and 80 ° C.
C is preferred. The reaction is performed for 10 minutes to 24 hours. The synthesis conditions are determined by conditions such as a metal compound, a ligand, a solvent, and a catalyst, and are not limited thereto.

Specific examples of the compounds of the general formulas [1] and [2] of the present invention are specifically shown in Table 1, but the present invention is not limited thereto.

[0033]

[Table 1]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

The compounds represented by the general formulas [1] and [2] of the present invention may be used alone or as a mixture in the same layer. If necessary, it may be used by mixing with another hole or electron injecting compound. Since the compound of the present invention has a large electron-transporting ability and an electron-injecting property from a cathode, it can be used very effectively for an electron-injecting layer of an organic EL device.

The organic EL device is a device in which one or more organic thin films are formed between an anode and a cathode. In the case of a single layer type, a light emitting layer is provided between an anode and a cathode. The light-emitting layer contains a light-emitting material and may further contain a hole-injection material or an electron-injection material for transporting holes injected from an anode or electrons injected from a cathode to the light-emitting material. The multilayer type is (anode / hole injection layer / light emitting layer /
There is an organic EL device having a multilayer structure of (cathode), (anode / light-emitting layer / electron injection layer / cathode), and (anode / hole injection layer / light-emitting layer / electron injection layer / cathode). The compounds represented by the general formulas [1] and [2] are compounds having strong fluorescence in a solid state and excellent in electroluminescence, and therefore can be used as a light emitting material. In addition, it can be used as an electron transporting host material in the same layer. In addition, since it has a good electron transporting ability, it can be used as an electron injection material for an electron injection layer between a light emitting layer and a cathode.

In the light emitting layer, if necessary, a light emitting material, a doping material, a hole injection material or an electron injection material may be used in addition to the compound of the general formula [1] or [2] of the present invention. it can. In the case of an organic thin film two-layer structure laminated in the order of (anode / hole injection layer / light emitting layer / cathode), the light emitting layer and the hole injection layer are separated. With this structure, the hole injection efficiency from the hole injection layer to the light emitting layer is improved, and the light emission luminance and the light emission efficiency can be increased. In this case, it is desirable that the light emitting material used in the light emitting layer itself has an electron transporting property, or that an electron injecting material is added to the light emitting layer. In the case of an organic thin film two-layer structure laminated in the order of (anode / light emitting layer / electron injection layer / cathode), the light emitting layer and the electron injection layer are separated. With this structure, the efficiency of electron injection from the electron injection layer to the light emitting layer is improved, and the light emission luminance and light emission efficiency can be increased. In this case, it is desirable that the light emitting material used for the light emitting layer itself has a hole transporting property, or that a hole injecting material is added to the light emitting layer.

The organic three-layer structure has a light emitting layer, a hole injecting layer, and an electron injecting layer to improve the efficiency of recombination of holes and electrons in the light emitting layer. As described above, the organic EL element has a multilayer structure, so that it is possible to prevent a decrease in luminance and life due to quenching. In such a device having a multilayer structure, if necessary, a light emitting material, a doping material, a hole injection material for transporting carriers, or an electron injection material can be used in combination. Further, each of the hole injection layer, the light emitting layer, and the electron injection layer may be formed of two or more layers. When the number of the hole injection layers is two or more, the layer in contact with the anode is called a hole injection layer, the layer between the hole injection layer and the light emitting layer is called a hole transport layer, and the electron injection layer has two layers. In the above cases, the layer in contact with the cathode is often referred to as an electron injection layer, and the layer between the electron injection layer and the light emitting layer is referred to as an electron transport layer.

In the organic EL device of the present invention, in the light emitting layer and the electron injection layer, if necessary, in addition to the compound of the general formula [1] or [2], a known light emitting material, doping material and hole injection may be used. Materials and electron injection materials can be used. When the compound of the general formula [1] or [2] is used in the light emitting layer, it can be used as a light emitting material or as a host material for emitting light by doping an appropriate doping material. By the light emission of the doping material, the light emission luminance and the light emission efficiency of the element can be improved, and a desired light emission color (light emission chromaticity) can be easily obtained. The ratio of the doping material in the light emitting layer can be changed by the luminous efficiency of the doping material, the concentration quenching, and the design of the device, but the abundance in the light emitting layer is preferably 0.001% by weight to 50% by weight. Is in the range where 0.01 to 10% by weight can show good element characteristics.

When the compound of the general formula [1] or [2] of the present invention is used as an electron injecting material or as a host material in a light emitting layer, the light emitting material or doping material includes anthracene, naphthalene, phenanthrene and pyrene. , Tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, coumarin, DCM, oxadiazole, aldazine, bisbenzoxazoline, styryl, bisstyryl, diamine,
Pyrazine, cyclopentadiene, imine, diphenylethylene, vinylanthracene, diaminocarbazole,
Pyran, thiopyran, polymethine, merocyanine, imidazole chelated oxinoid compound, quinacridone, rubrene, quinoline metal complex, benzoquinoline metal complex, 2-phenylbenzothiazole metal complex, 2-phenylbenzoxazole metal complex, aminoquinoline metal complex, other metals There are, but are not limited to, complex compounds and the like, and derivatives of the above compounds.

Among them, the light emitting material or the doping material used in the light emitting layer is preferably a metal complex compound, a low molecular light emitting compound such as a styryl or bisstyryl compound or a diamine compound, or a conjugated polymer. .

The metal complex compounds include (8-hydroxyquinolinato) lithium, bis (8-hydroxyquinolinato) zinc, bis (8-hydroxyquinolinato) manganese, bis (8-hydroxyquinolinato) copper, and tris (8-hydroxyquinolinato) manganese. 8
-Hydroxyquinolinato) aluminum, tris (8-
(Hydroxyquinolinato) gallium, tris (8-hydroxyquinolinato) indium, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis (10-hydroxybenzo [h] quinolinato) zinc, bis (10-
Hydroxybenzo [h] quinolinato) magnesium, tris (10-hydroxybenzo [h] quinolinato) aluminum, tris (10-hydroxybenzo [h] quinolinato) gallium, bis (2-methyl-8-quinolinato) zinc, bis (2 -Methyl-8-quinolinato) chlorogallium, bis (2-methyl-8-quinolinato) (o-
Cresolate) gallium, bis (2-methyl-8-quinolinato) (1-phenolate) aluminum, bis (2
-Methyl-8-quinolinato) (1-phenolato) gallium, bis (2-methyl-8-quinolinato) (1-naphtholate) gallium, bis (2-methyl-8-quinolinato) (4-biphenolato) gallium, bis [2- (2
-Benzoxazolinato) phenolate] zinc, bis [2- (2-benzothiazolinato) phenolate] zinc, bis [2- (2-benzotriazolinato) phenolate] zinc and the like, but are not limited thereto. Not something. These compounds may be used alone or as a mixture of two or more.

The styryl or bisstyryl compound suitable for the light emitting material or the doping material includes a phenylene group, a naphthylene group, a biphenylene group, an anthranylene group, a pyrenylene group, and a thiolene group each having a substituent as a linking group or a residue. A phenylene group, a divalent linking group such as triphenylamine or N-ethylcarbazole,
Or a phenyl group which may have a substituent,
Examples include naphthyl group, biphenyl group, anthranyl group, pyrenyl group, thiophenyl group, and styryl or bisstyryl compounds such as triphenylamine and N-ethylcarbazole residues. Specifically, stilbene, diphenylamino-1,4-bisstyrylbenzene, ditolylamino-1,4-bisstyrylbenzene, diphenylamino-4,4′-bisstyrylbiphenyl, 3-
(N-ethylcarbazole) -4,4'-bisstyrylbiphenyl, bis [4,4 '-(2,2-diphenylvinyl)] biphenyl and the like. These compounds may be used alone or as a mixture of two or more.

Examples of the conjugated polymer include a nitrogen atom,
There is a polymer having a repeating unit of 2 or more and 10,000 or less, which is polymerized with an arylene group which may contain an oxygen atom or a sulfur atom alone or with a conjugate group such as a vinyl group. Specifically, poly (p-phenylene), poly (p-thiophene), poly (p-phenylenevinylene), poly (2,5
-Dipentyl-p-phenylenevinylene), poly (2,
5-dipentyl-m-phenylenevinylene), poly (2,5-dioctyl-p-phenylenevinylene), poly (2,5-dihexyloxy-p-phenylenevinylene), poly (2,5-dihexylthio-p-) Phenylenevinylene), poly (2,5-didecyloxy-p-phenylenevinylene), poly (2-methoxy-5-hexyloxy-p-phenylenevinylene), poly (2,5-thienylenevinylene), poly (3- n-octyl-2,5
-Thienylenevinylene), poly (1,4-naphthalenevinylene), poly (9,10-anthracenevinylene), and copolymers thereof. These compounds may be used alone or as a mixture of two or more.

As the arylamine compound, there is a compound in which a substituted diamino group is substituted for an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom. Specifically, N, N, N ', N'-(4-methylphenyl)
-1,4-phenyl-4,4′-diamine, N, N,
N ′, N ′-(4-methylphenyl) -1,3-phenyl-4,4′-diamine, N, N′-diphenyl-N,
N '-(3-methylphenyl) -1,1'-biphenyl-4,4'-diamine, N, N'-(4-methylphenyl) -N, N '-(4-n-butylphenyl)- Phenanthrene-9,10-diamine, N, N′-diphenyl-N, N′-dinaphthyl-1,1′-biphenyl-4,
4'-diamine, N, N, N ', N'-(4-n-octylphenyl) -9,10-anthranyl-4,4'-
Diamine, N, N, N'N '-[4- (α, α-dimethylbenzyl) phenyl] -anthranyl-9,10-diamine and the like. These compounds may be used alone or as a mixture of two or more.

The hole injecting material which can be used as a hole injecting layer or a hole injecting material of a device using the metal complex compound of the present invention as a light emitting material, a host material or an electron injecting material is Has the ability to inject holes, has the effect of injecting holes from the anode, the excellent hole injecting effect on the light emitting layer or the light emitting material, and the electron injection layer or electron injection of excitons generated in the light emitting layer Compounds that prevent transfer to a material and have excellent thin film forming ability are exemplified. Specifically, phthalocyanine compounds, naphthalocyanine compounds, porphyrin compounds, oxadiazole, triazole, imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone,
Acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine-type triphenylamine, styrylamine-type triphenylamine, diamine-type triphenylamine, and derivatives thereof, and polymers such as polyvinylcarbazole, polysilane, and conductive polymers There are materials and the like, but it is not limited to these.

When the metal complex compound of the present invention is used as a light emitting material or a host material, the electron injecting material that can be used has the ability to inject electrons from the cathode, and is used in the light emitting layer or the light emitting material. Compounds that have an excellent electron-injection effect, prevent excitons generated in the light-emitting layer from migrating to the hole-injection layer or the hole-injection material, and have excellent thin-film-forming ability. For example, quinoline metal complex,
Oxadiazole, benzothiazole metal complex, benzoxazole metal complex, benzimidazole metal complex,
Fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxadiazole, thiadiazole, tetrazole, perylenetetracarboxylic acid,
Examples include, but are not limited to, fluorenylidenemethane, anthraquinodimethane, anthrone, and the like, and their derivatives. Alternatively, an electron accepting material may be added to the hole injecting material and an electron donating material may be added to the electron injecting material to sensitize the material.

The organic EL device having a multilayer structure can prevent a decrease in luminance and life due to quenching. If necessary, a combination of two or more kinds of light emitting materials, doping materials, hole injecting materials for injecting carriers, and electron injecting materials can also be used. Also,
The hole injection layer, the light-emitting layer, and the electron injection layer may each be formed in a layer structure of two or more layers, and an element structure in which holes or electrons are efficiently injected from the electrode and transported in the layer is selected. You.

As the conductive material used for the anode of the organic EL element, those having a work function of more than 4 eV are suitable, and include carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, and platinum. , Palladium and their alloys, tin oxide used for ITO substrate, NESA substrate, metal oxide such as indium oxide,
Further, an organic conductive resin such as polythiophene or polypyrrole is used.

As the conductive material used for the cathode, 4
A metal or a metal alloy having a work function smaller than eV is suitable, and magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, aluminum, and the like and alloys thereof are used.
Representative examples of the alloy include magnesium / silver, magnesium / indium, and lithium / aluminum, but are not limited thereto. The ratio of the alloy is controlled by the heating temperature, atmosphere, and degree of vacuum, and an appropriate ratio is selected. The anode and the cathode may be formed by two or more layers if necessary.

In the organic EL device, at least one of them is desirably sufficiently transparent in the emission wavelength region of the device in order to emit light efficiently. Further, it is desirable that the substrate is also transparent. The transparent electrode is set so as to secure a predetermined translucency by a method such as vapor deposition or sputtering using the above conductive material. The electrode on the light emitting surface desirably has a light transmittance of 10% or more. The substrate is not limited as long as it has mechanical and thermal strength and is transparent, but examples thereof include a glass substrate and transparent resins such as polyethylene, polyethersulfone, and polypropylene.

Each layer of the organic EL device according to the present invention can be formed by any of dry film forming methods such as vacuum deposition, sputtering, and ion plating, and wet film forming methods such as spin coating and dipping. Can be. The thickness is not particularly limited, but each layer needs to be set to an appropriate thickness. If the film thickness is too large, a large applied voltage is required to obtain a constant light output, resulting in poor efficiency. If the film thickness is too small, pinholes and the like are generated, and sufficient light emission luminance cannot be obtained even when an electric field is applied. A normal film thickness in the range of 5 nm to 10 μm is suitable,
More preferably, the range is from 10 nm to 0.2 μm.

In the case of the wet film forming method, a material for forming each layer is dissolved or dispersed in an appropriate solvent such as chloroform, tetrahydrofuran, dioxane or the like to form a thin film.
The solvent may be any. In any of the thin films, an appropriate resin or additive may be used in order to improve film forming properties, prevent pinholes in the film, and the like. Examples of such a resin include insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate, and cellulose; and photoconductive materials such as poly-N-vinyl carbazole and polysilane. And conductive resins such as polythiophene and polypyrrole. Examples of the additive include an antioxidant, an ultraviolet absorber, and a plasticizer.

In order to improve the stability of the organic EL device obtained according to the present invention with respect to temperature, humidity, atmosphere, etc., a protective layer is provided on the surface of the device or silicon oil is sealed to protect the entire device. It is also possible.

As described above, when the compound of the general formula [1] or [2] is used as an electron injecting material in the organic EL device of the present invention, the ability to transport electrons and the efficiency of injecting electrons from the cathode. And when used as a luminescent material, luminous efficiency and luminous brightness could be increased. In addition, since the electron transport property and the electron injection efficiency in the thin film layer of the element are high, the element is extremely stable. As a result, high emission luminance can be obtained with a low driving current, which has been a major problem up to now. The light emission lifetime was also significantly improved.

The organic EL device prepared by using the organic EL device material of the present invention can be used as a flat panel display such as a wall-mounted television or a flat illuminant as a light source for a copier or a printer, or a light source for a liquid crystal display or an instrument. It can be applied to display boards and sign lights, and its industrial value is great.

[0065]

The present invention will be described in more detail with reference to the following examples. (Synthesis example) Synthesis method of compound (3) 1.83 g of zinc acetate in 250 ml of anhydrous ethanol,
-(2-Hydroxyphenyl-5-phenyl-N-phenyl-triazole (1.55 g) is placed in a 500 ml flask and heated in a reflux state to dissolve everything. After stirring for 3 hours, the mixture is left to cool. The precipitated target product was taken out by suction filtration to obtain 2.1 g of a white crystal, which was identified as Compound (3) by mass spectrometry, NMR spectrum, infrared absorption spectrum and the like.

Hereinafter, examples using the compound of the present invention will be described. In this example, characteristics of an organic EL element having an electrode area of 2 mm × 2 mm were measured.

Example 1 On a glass plate with a cleaned ITO electrode (10Ω / □),
4,4'-bis [N- (1-naphthyl) -N-phenyl
Amino] biphenyl (α-NPD) is vacuum deposited to form a film
A hole injection layer having a thickness of 40 nm was obtained. Then, compound (1)
Was deposited to obtain a 40 nm-thick electron-injection light-emitting layer. That
A film made of an alloy of magnesium and silver mixed at a ratio of 10: 1
An organic EL element was obtained by forming an electrode having a thickness of 100 nm. each
10 organic layers^-6Substrate temperature at room temperature in Torr vacuum
Deposited under the following conditions. This device has a luminance of 7 at DC voltage of 5V.
5 (cd / m^Two), Maximum emission luminance 3500 (cd /
m^Two) Light emission with luminous efficiency of 0.3 (lm / W) at 5V
was gotten. Next, 3 (mA / cm ^Two)
As a result of a life test in which the device
Of の or more was maintained for 1000 hours or more. Less than
The anode of the element used in the following example is an IT
An O electrode was used.

Examples 2 to 18 Organic EL devices were prepared in the same manner as in Example 1 except that the compounds shown in Table 2 were used instead of the compound (1) in the light emitting layer. This device exhibited the emission characteristics shown in Table 2.
Next, at a current density of 3 (mA / cm ² ), as a result of a life test in which the device was continuously caused to emit light, light emission of 以上 or more of the initial luminance was maintained for 1000 hours or more.

[0069]

[Table 2]

Example 19 A compound (13) was vacuum-deposited on a washed glass plate with an ITO electrode to form a 100-nm-thick light-emitting layer, on which an alloy obtained by mixing magnesium and silver at a ratio of 10: 1 was used. An electrode having a thickness of 150 nm was formed to obtain an organic EL device. The light emitting layer and the cathode were deposited at a substrate temperature of room temperature in a vacuum of 10 ^-6 Torr. This element has a DC voltage of 5
At 10 V, the emission luminance is 10 (cd / m ² ), and the maximum emission luminance is 150
0 (cd / m ² ), luminous efficiency at 5 V of 0.2 (lm / m ² )
Green light emission of W) was obtained. Next, at a current density of 3 (mA / cm ² ), as a result of a life test in which the device was continuously caused to emit light, light emission of 以上 or more of the initial luminance was maintained for 1000 hours or more.

Example 20 N, N '-(3) was placed on a cleaned glass plate with ITO electrodes.
-Methylphenyl) -N, N'-diphenyl-1,1 '
-Biphenyl-4,4'-diamine (TPD) was vacuum-deposited to obtain a hole injection layer having a thickness of 40 nm. Next, the compound (15) is vacuum-deposited to form a light-emitting layer having a thickness of 40 nm, and a tris (8-hydroxyquinolinato) aluminum complex (Alq3) is vacuum-deposited thereon to form a light-emitting layer having a thickness of 30 nm.
Was obtained. And one more magnesium and silver
An electrode having a thickness of 100 nm was formed from an alloy mixed at 0: 1 to obtain an organic EL device. Each organic layer was deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device emits light from compound (15) having a light emission luminance of 1550 (cd / m ² ) at a DC voltage of 5 V, a maximum light emission luminance of 4000 (cd / m ² ), and a light emission efficiency of 0.4 (lm / W) at 5 V. was gotten. Next, at a current density of 3 (mA / cm ² ), as a result of a life test in which the device was continuously lit, 1 / l of the initial luminance was obtained.
Two or more light emissions were held for 1000 hours or more.

Example 21 4, 4 ′, 4 ″ was placed on a washed glass plate with an ITO electrode.
-Tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine was vacuum deposited to a film thickness of 40
nm of the first hole injection layer was obtained. Next, NPD was vacuum-deposited to obtain a second hole injection layer having a thickness of 10 nm. further,
A compound (12) is vacuum-deposited to form a 30-nm-thick light-emitting layer, and a bis (2-methyl-8-hydroxyquinolinato) (1-phenolate) gallium complex is further vacuum-deposited to inject a 30-nm-thick electron. A layer was formed, and an electrode having a thickness of 150 nm was formed thereon using an alloy in which aluminum and lithium were mixed at a ratio of 25: 1 to obtain an organic EL device. Each organic layer was deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a light emission luminance of 6 at a DC voltage of 5 V.
00 (cd / m ² ), maximum emission luminance 3300 (cd / m ² )
m ² ), Compound (12) having a luminous efficiency of 0.3 (lm / W)
Luminescence was obtained. Next, at a current density of 3 (mA / cm ² ), as a result of a life test in which the device was continuously caused to emit light, light emission of １ ／ or more of the initial luminance was maintained for 1500 hours or more.

Example 24 In the first hole injection layer, 4,4 ′, 4 ″ -tris [N- (3
-Methylphenyl) -N-phenylamino] An organic EL device was produced in the same manner as in Example 21 except that copper phthalocyanine was used in a film thickness of 5 nm instead of triphenylamine. This device has a luminance of 170 (c) at a DC voltage of 5 V.
d / m ² ), maximum light emission luminance 4900 (cd / m ² ), 5 V
In this case, light emission from the compound (23) having a light emission efficiency of 0.6 (lm / W) was obtained. Next, at a current density of 3 (mA / cm ² ), as a result of a life test in which the device was continuously lit,
Light emission of 1/2 or more of the initial luminance was maintained for 1200 hours or more.

Example 25 NPD was vacuum-deposited on a cleaned glass plate with ITO electrodes to obtain a hole injection layer having a thickness of 40 nm. Next, the compound (23) and rubrene were deposited at a weight ratio of 25: 1 to form a light emitting layer having a thickness of 40 nm, and Alq3 was deposited thereon to obtain an electron injection layer having a thickness of 30 nm. On top of this, an alloy of magnesium and silver mixed at a ratio of 10: 1 to a film thickness of 100
An organic EL device was obtained by forming an electrode having a thickness of 10 nm. Each organic layer was deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a light emission luminance of 300 (c) at a DC voltage of 5 V.
d / m ² ), maximum emission luminance 14000 (cd / m ² ), 5
Yellow luminescence from rubrene having a luminous efficiency of 1.7 (lm / W) at V was obtained. Next, at a current density of 3 (mA / cm ² ), as a result of a life test in which the device was continuously lit,
Light emission of 1/2 or more of the initial luminance was maintained for 1000 hours or more.

Example 26 In the light emitting layer, quinacridone was used in a ratio of 100: 1 instead of rubrene.
An organic EL device was produced in the same manner as in Example 25 except that the weight ratio was used. This device has a light emission luminance of 280 (cd / m ² ) at a DC voltage of 5 V and a maximum light emission luminance of 22000.
(Cd / m ² ), luminous efficiency at 5 V of 2.5 (lm /
Light emission from quinacridone in W) was obtained. Then 3 (m
As a result of a life test in which the device was continuously lit at a current density of A / cm ² ), luminescence equal to or more than の of the initial luminance was 1%.
Held for over 000 hours.

The organic EL device of the present invention achieves an improvement in luminous efficiency, luminous brightness and a long life, and is used together with a luminescent material, a doping material, a hole injection material, an electron injection material, and a sensitizer. It does not limit the agent, resin, electrode material and the like, and the element manufacturing method.

[0077]

According to the present invention, it is possible to obtain an organic EL device having higher luminous efficiency, higher luminance and longer life than the conventional one.

Claims (5)

[Claims] 1. A material for an organic electroluminescence device comprising a compound represented by the following general formula [1] or [2]. General formula [1] Wherein R ¹ and R ² are each independently a hydrogen atom,
Represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aromatic heterocyclic group. R ^{3 to} R ⁶ each independently represent a hydrogen atom,
A halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aromatic heterocyclic group, Or a substituted or unsubstituted aromatic heterocyclic oxy group.
However, R ^{3 to} R ⁶ may be bonded together by adjacent substituents to be integrated. M represents a divalent to tetravalent metal, and n
Represents an integer of 1 to 4. General formula [2] Wherein R ¹ and R ² are each independently a hydrogen atom,
Represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aromatic heterocyclic group. R ^{3 to} R ⁶ each independently represent a hydrogen atom,
A halogen atom, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted aromatic heterocyclic group, Or a substituted or unsubstituted aromatic heterocyclic oxy group.
However, R ^{3 to} R ⁶ may be bonded together by adjacent substituents to be integrated. Ar each independently represents a substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic group. M represents a divalent to tetravalent metal,
m represents an integer of 1 to 3. ] 2. A light emitting material for an organic electroluminescent device, comprising a compound represented by the general formula [1] or [2] and a doping material. 3. An organic electroluminescence device in which an organic compound thin film including a light emitting layer is formed between a pair of electrodes, wherein at least one layer is a layer containing the organic electroluminescence device material according to claim 1 or 2. element. 4. An organic electroluminescence device in which a plurality of organic compound thin films including a light emitting layer are formed between a pair of electrodes, wherein the light emitting layer is a layer containing the organic electroluminescent device material according to claim 1 or 2. Organic electroluminescent element. 5. An organic electroluminescent device comprising a plurality of organic compound thin films including a light emitting layer formed between a pair of electrodes, wherein at least one layer between the cathode and the light emitting layer is provided. An organic electroluminescence device which is a layer containing a luminescence device material. [0000]