JPH09328679A - Electron injecting material for organic electroluminescent element and organic electroluminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electron injecting material, comprising a specific compound, excellent electron transport ability, excellent in injection efficiency from a cathode, having a higher luminous efficiency and a higher luminance than those of a conventional one and capable of producing a long-lived organic electoluminescent element. SOLUTION: This electron injecting material for an organic electroluminescent element comprises a compound of the formula [X is O, S, NH or CH2 ; R<1> to R<8> are each H, a halogen, a (substituted)alkoxy, a (substituted)amino or a (substituted)alkyl; M is a bi- or a trivalent metal; (n) is 2 or 3], e.g. a bis[2-(2- hydroxyphenyl)benzoxazole]zinc complex. Furthermore, the exemplified compound is obtained by reacting 2-(2-hydroxyphenyl)benzoxazole with anhydrous zinc acetate in ethanol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence (EL) used for a flat light source or a light emitting display.
This is based on an electron injection material for a device and a light emitting device with high luminance and long life.

[0002]

2. Description of the Related Art An EL device using an organic substance is expected to be used as an inexpensive, large-area, full-color display device of a solid light emitting type, and many developments have been made. Generally, an EL is composed of a light emitting layer and a pair of counter electrodes sandwiching the light emitting layer. For light emission, when an electric field is applied between both electrodes, electrons are injected from the cathode side and holes are injected from the anode side.
This is a phenomenon in which electrons and holes are recombined in the light emitting layer and energy is emitted as light when the energy level returns from the conduction band to the valence band.

[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.
2. Description of the Related Art In recent years, an organic EL in which a thin film containing an organic compound having high fluorescence quantum efficiency that emits light at a low voltage of 10 V or less is laminated.
Devices have been reported and are of interest (see Applied Physics Letters, vol. 51, p. 913, 1987). In this method, high-luminance green light emission is obtained by laminating a metal chelate complex as a phosphor layer and an amine compound as a hole injection layer, and the luminance is several hundred (cd / m ²⁾ under a DC voltage of 6 to 7 V. ), The maximum luminous efficiency is 1.5 (lm)
/ W), which achieves performance close to the practical range.

The hole injection material for the organic layer of the organic EL device is
It is preferable that the material be a material having a good hole injection efficiency from the anode and capable of efficiently transporting the injected holes toward the light emitting layer. For that purpose, it is required that the ionization potential is small, the hole mobility is large, and the stability is excellent. It is preferable that the electron injecting material is a material having a high electron injection efficiency from the cathode and capable of efficiently transporting the injected electrons toward the light emitting layer. For that purpose, it is required that the electron affinity is large, the electron mobility is large, and the stability is excellent.

The hole-injecting materials proposed to date include oxadiazole derivatives (US Pat. No. 3,189,189,
447), oxazole derivatives (US Pat. No. 3,25
7,203), hydrazone derivatives (U.S. Pat.
17,462, JP-A-54-59,143, U.S. Pat. No. 4,150,978), triarylpyrazoline derivatives (U.S. Pat.
-93,224, JP-A-55-108,667),
Arylamine derivatives (US Pat. No. 3,180,730)
No. 4,232,103, JP-A-55-1
44,250, JP-A-56-119,132) and stilbene derivatives (JP-A-58-190,953, JP-A-59-195,658).

As electron injection materials, oxadiazole derivatives (JP-A-2-216791), perinone derivatives (JP-A-2-289676), perylene derivatives (JP-A-2-189890, JP-A-3-791). issue),
There are quinacridone derivatives (JP-A-6-330031) and the like, but the electron injection characteristics from the cathode to the organic layer of the organic EL device using this electron injection material were not sufficient.

The organic EL devices to date have been improved in luminous efficiency by improving the structure, but have not yet had a sufficient device life. In particular, the injection efficiency due to the contact between the cathode metal and the interface of the organic layer is low, and the heat resistance of the organic layer in contact with the electrode has become a serious problem. Therefore, development of an electron injection material is desired for the development of an organic EL device having higher luminous efficiency and a long life.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a durable electron injection material having excellent electron injection and transport ability, and further using the electron injection material. It is an object of the present invention to provide an organic EL device having high brightness and long life. As a result of intensive studies by the present inventors,
The present inventors have found that an organic EL element using at least one electron injection material represented by the general formula [1] has a large electron injection ability and excellent life stability during repeated use, and thus reached the present invention.

[0009]

That is, the present invention is an electron injecting material for an organic electroluminescent device represented by the following general formula [1]. General formula [1]

[0010]

Embedded image

[In the formula, X is --O--, --S--, --NH.
-, - CH ₂ - represents a. R ^{1 to} R ⁸ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, or a substituted or unsubstituted alkyl group. M represents a divalent or trivalent metal atom, and n represents 2 or 3. ]

The present invention further provides an organic electroluminescence device comprising an organic compound thin film layer including a light emitting layer and an electron injection layer between a pair of electrodes, wherein the electron injection layer is the electron injection material for the organic electroluminescence device. It is an organic electroluminescent element which is a layer containing.

Further, the present invention is the above organic electroluminescent device, wherein the light emitting layer is a layer containing a metal complex compound.

Further, in the present invention, the light emitting layer has the following general formula [2].
The above organic electroluminescence device is a layer containing the compound represented by. General formula [2]

[0015]

[Chemical 6]

[In the formula, Ar ¹ is an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom. R ⁹
To R ¹² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, or an aryl group which may have a substituted or unsubstituted nitrogen atom. ]

Further, in the present invention, the light emitting layer has the following general formula [3].
The above organic electroluminescence device is a layer containing the compound represented by. General formula [3]

[0018]

[Chemical 7]

[In the formula, Ar ² is an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom. R ¹³
To R ¹⁴ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aryl group which may have a nitrogen atom. m represents an integer of 2 to 10,000. ]

Further, in the present invention, the light emitting layer has the following general formula [4].
The above organic electroluminescence device is a layer containing the compound represented by. General formula [4]

[0021]

Embedded image

[Wherein B ^{1 to} B ⁴ are independently
It represents a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. G represents a substituted or unsubstituted arylene group. ]

Further, the present invention is the above-mentioned organic electroluminescence device provided with a hole injection layer.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION R ^{1 to} R ⁸ of the compound represented by the general formula [1] of the present invention are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted It represents an amino group or a substituted or unsubstituted alkyl group. Specific examples of the halogen atom include fluorine, chlorine, bromine, and iodine. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group and a butoxy group. Specific examples of the amino group include an amino group, a dimethylamino group, a diethylamino group, a diphenylamino group, a ditolylamino group and an N-naphthyl-1-phenylamino group. Specific examples of the alkyl group include:
Methyl group, ethyl group, propyl group, butyl group, sec-
There are butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, trichloromethyl group and the like.

Specific examples of the substituent which may be added to the above-mentioned groups include halogen atom of fluorine, chlorine, bromine and iodine, methyl group, ethyl group, propyl group, butyl group and s.
ec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, trichloromethyl group, trifluoromethyl group, 2,2,2
-Trifluoroethyl group, 2,2,3,3-tetrafluoropropyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoro-2 A substituted or unsubstituted alkyl group such as -propyl group, 2,2,3,3,4,4-hexafluorobutyl group, 2-methoxyethyl group, methoxy group, n-butoxy group,
tert-butoxy group, trichloromethoxy group, trifluoroethoxy group, pentafluoropropoxy group, 2,
2,3,3-tetrafluoropropoxy group, 1,1,
1,3,3,3-hexafluoro-2-propoxy group,
A substituted or unsubstituted alkoxy group such as a 6- (perfluoroethyl) hexyloxy group, a cyano group, a nitro group,
Amino group, methylamino group, diethylamino group, ethylamino group, diethylamino group, dipropylamino group, dibutylamino group, diphenylamino group, and other mono- or di-substituted amino groups, bis (acetoxymethyl) amino group, bis (acetoxyethyl group) ) Amino group, bisacetoxypropyl) amino group, bis (acetoxybutyl) amino group, and other acylamino groups, hydroxyl group, siloxy group, acyl group, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl group, propylcarbamoyl group Group, butylcarbamoyl group, carbamoyl group such as phenylcarbamoyl group, carboxylic acid group, sulfonic acid group, imide group and the like.

In the general formula [1], preferable metal atoms as M are beryllium, zinc, cadmium, magnesium, calcium, cobalt, nickel, iron,
It shows copper, strontium, scandium, aluminum, gallium or indium, but is not limited to these. n varies depending on the valence of the metal atom, and is 2 in the case of a divalent metal and 3 in the case of a trivalent metal.

Typical examples of the compound of the general formula [1] used in the electron injection layer of the organic EL device of the present invention will be specifically illustrated below, but the present invention is limited to the following typical examples. is not.

[0028]

[Table 1]

[0029]

[0030]

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

The organic EL element is an element in which a single-layer or multi-layer organic thin film is formed between an anode and a cathode. In the case of the single layer type, a light emitting layer is provided between the anode and the cathode. The light-emitting layer may contain a light-emitting material and may further contain a hole-injection material or an electron-injection material in order to transport holes injected from an anode or electrons injected from a cathode to the light-emitting material. The light emitting material may have a hole transporting property or an electron transporting property. The multilayer type includes (anode / hole injection layer / light emitting layer / cathode), (anode / light emitting layer / electron injection layer / cathode), (anode / hole injection layer / light emitting layer / electron injection layer /
There is an organic EL element in which a multilayer structure such as a cathode is laminated. Since the compound of the general formula [1] has a large electron transporting ability, it can be used as an electron injecting material for the electron injecting layer between the light emitting layer and the cathode.

If necessary, in addition to the compound of the general formula [1] of the present invention, a light emitting material, a doping material, a hole injecting material or an electron injecting material can be used in the light emitting layer. In the case of the organic thin film two-layer structure in which (anode / hole injection layer / light emitting layer / cathode) is laminated in this order, 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 brightness 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 the electron injecting material is added to the light emitting layer. In the case of an organic thin film two-layer structure in which (anode / light emitting layer / electron injection layer / cathode) is stacked in this order, the light emitting layer and the electron injection layer are separated. With this structure, the electron injection efficiency from the electron injection layer to the light emitting layer is improved, and the light emission brightness and the 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 thin film 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 having a multi-layered structure can prevent a decrease in brightness and life due to quenching. In such a device having a multilayer structure, if necessary, a light emitting material, a doping material, a hole injecting material for carrying carriers, and an electron injecting material can be used in combination. Also, a hole injection layer, a light emitting layer,
The electron injection layer may be formed of two or more layers. When the hole injection layer has two or more layers, the layer in contact with the anode is called the hole injection layer, the layer between the hole injection layer and the light emitting layer is called the hole transport layer, and the electron injection layer has two layers. In the above cases, the layer in contact with the cathode is often called an electron injection layer, and the layer between the electron injection layer and the light emitting layer is called an electron transport layer.

In the organic EL device of the present invention, in the light emitting layer and the electron injecting layer, if necessary, in addition to the compound of the general formula [1], known light emitting materials, doping materials, hole injecting materials and electron injecting materials are used. Materials can be used.

Known light-emitting materials or doping materials include anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, coumarin,
Oxadiazole, aldazine, bisbenzoxazoline, bisstyryl, pyrazine, cyclopentadiene, oxine, aminoquinoline, imine, diphenylethylene, vinylanthracene, diaminocarbazole, pyran, thiopyran, polymethine, merocyanine, imidazole chelated oxinoid compound, quinacridone, There are, but not limited to, rubrene and derivatives thereof.

Organic EL using the electron injection material of the present invention
Suitable compounds for the light emitting material of the light emitting layer of the device include metal complex compounds and compounds represented by the general formulas [2] to [4]. Examples of the metal complex compound include (8-hydroxyquinolinonato) lithium, bis (8-hydroxyquinolinonato) zinc, and bis (8-hydroxyquinolinonato).
Manganese, bis (8-hydroxyquinolinonato) copper, tris (8-hydroxyquinolinonato) aluminum, tris (8-hydroxyquinolinonato) gallium, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis ( 10-hydroxybenzo [h] quinolinato)
Zinc, bis (10-hydroxybenzo [h] quinolinato) magnesium, tris (10-hydroxybenzo [h] quinolinato) aluminum, 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-Phenolate) gallium, bis (2-methyl-8)
-Quinolinato) (1-naphtholato) aluminum, bis (2-methyl-8-quinolinato) (1-naphtholato) gallium, bis (2-methyl-8-quinolinato)
(1-Biphenolate) gallium, bis (2- [2-benzoxazolinato] phenolate) zinc, bis (2-
[2-benzothiazolinato] phenolate) zinc, bis (2- [2-benzotriazolinato] phenolato) zinc, and the like, but not limited thereto. These compounds may be used alone or as a mixture of two or more.

Ar ¹ of the compound represented by the general formula [2] is an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom. Specific linking groups include a phenylene group which may have a substituent, a naphthylene group, a biphenylene group, an anthranylene group, a pyrenylene group, a thiophenylene group, a divalent residue of triphenylamine, and 2 of N-ethylcarbazole. There are, but are not limited to, valent residues. Examples of these substituents include the same substituents as R ^{1 to} R ⁸ of the compound represented by the above general formula [1]. R ^{9 to} R ¹² are the same substituents as R ^{1 to} R ⁸ .

Typical examples of the compound of the general formula [2] used in the light emitting layer of the organic EL device of the present invention will be specifically illustrated below, but the invention is not limited to the following typical examples. These compounds may be used alone or as a mixture of two or more.

[0040]

[Table 2]

Ar ² of the compound represented by the general formula [3] is an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom. A specific linking group is the same linking group as Ar ¹ . As the substituent of these linking groups, R ^{1 of the} compound represented by the above general formula [1] can be used.
Same substituents as to R ⁸ and the like. The repeating unit is
It is 2 or more and 10000 or less. Representative examples of the conjugated polymer are specifically illustrated, but the present invention is not limited to the following representative examples. Examples of the conjugated polymer include poly (p
-Phenylene), poly (p-phenylenevinylene), poly (2,5-dipentyl-p-phenylenevinylene),
Poly (2,5-dipentyl-m-phenylene vinylene), poly (2,5-dioctyl-p-phenylene vinylene), poly (2,5-dihexyloxy-p-phenylene vinylene), poly (2,5-dihexyl) Oxy-m
-Phenylene vinylene), poly (2,5-dihexylthio-p-phenylene vinylene), poly (2,5-didecyloxy-p-phenylene vinylene) poly (2-methoxy-5-hexyloxy-p-phenylene vinylene),
Poly (2-methoxy-5- (3'-methyl-butoxy)
-P-phenylene vinylene, poly (2,5-thienylene vinylene), poly (3-n-octyl-2,5-thienylene vinylene), poly (1,4-naphthalene vinylene), poly (9,10- Anthracene vinylene) and their copolymers. These compounds may be used alone or as a mixture of two or more.

B ^{1 to} B of the compound represented by the general formula [4]
⁴ is a substituted or unsubstituted 6 to 20 carbon atom
Any aryl group may be used. Specific aryl groups include phenyl group, naphthyl group, anthranyl group, pyrenyl group, biphenyl group and the like. G may be a substituted or unsubstituted arylene group. Specific arylene groups include a phenylene group, a naphthylene group, an anthranylene group, a pyrenylene group and a biphenylene group.
Examples of the substituent of the aryl group or the arylene group include the substituents described in R ^{1 to} R ⁸ of the compound represented by the general formula [1].

Typical examples of the compound of the general formula [4] used in the light emitting layer of the organic EL device of the present invention will be specifically illustrated below, but the invention is not limited to the following typical examples. These compounds may be used alone or as a mixture of two or more.

[0044]

[Table 3]

[0045]

[0046]

The hole injecting material that can be used in the organic EL device of the present invention has the ability to transport holes and has an excellent hole injecting effect on the light emitting layer or the light emitting material. Examples of the compound include a compound capable of preventing the excitons from moving to the electron injection layer or the electron transport material and having an excellent thin film forming ability. Specifically, phthalocyanine, naphthalocyanine, porphyrin, oxadiazole, triazole,
Imidazole, imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine triphenylamine, styrylamine triphenylamine, diamine triphenyl Examples include amines and the like, derivatives thereof, and high molecular materials such as polyvinyl carbazole, polysilane, and conductive polymers, but are not limited thereto.

The electron injecting material that can be used in combination with the compound of the general formula [1] used in the organic EL device of the present invention has the ability to transport electrons and is excellent in electron injecting into the light emitting layer or the light emitting material. A compound which has an effect and prevents excitons generated in the light emitting layer from moving to the hole injecting layer or the hole transporting material and has an excellent thin film forming ability can be mentioned. For example, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxadiazole, thiadiazole, triazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane,
Examples include, but are not limited to, anthrones, metal complexes, and derivatives thereof. These electron injecting materials can be used in the same layer as the compound of the general formula [1]. However, the electron injecting material should be laminated with an electron injecting layer formed of the compound of the general formula [1] to improve the electron injecting effect. Can also. In addition, sensitization can be performed by adding an electron accepting material to the hole injecting material and adding an electron donating material to the electron injecting material.

The compound of the general formula [1] of the present invention can be used in at least one layer between the light emitting layer and the cathode. 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 or the like is sealed to protect the entire device. It is also possible.

As the conductive material used for the anode, 4
A metal having a work function larger than eV is suitable, and A
u, Pt, Ag, Cu, Al and other metals, metal alloys, IT
Organic conductive resins such as O, NESA or polythiophene or polypyrrole are used.

As the conductive material used for the cathode, 4
A metal or metal alloy having a work function smaller than eV is suitable. As the material, Al, In, Mg, L
i, metal such as Ca, or Mg / Ag, Li / A
1, alloys such as Mg / In. The anode and the cathode may be formed of two or more layers if necessary. The anode and the cathode are manufactured by a known film forming method such as vapor deposition, sputtering, ion plating, and a plasma gun.

In an organic EL device, at least one of a cathode and an anode is preferably sufficiently transparent in an emission wavelength region of the device to efficiently emit light. Further, it is desirable that the substrate is also transparent. The transparent electrode is set using the above-described conductive material by a method such as vapor deposition, sputtering, or ion plating so as to secure a predetermined translucency. The light transmittance of the electrode on the light emitting surface side is desirably 10% or more.

The substrate may be any substrate as long as it has mechanical and thermal strength and is transparent. Examples thereof include a glass substrate and a plate-like or film-like material such as polyethylene, polyethersulfone, polypropylene and polyimide. Can be

Each layer of the organic EL device of the present invention is formed by any of dry film forming methods such as vacuum evaporation, sputtering, ion plating and plasma gun methods, and wet film forming methods such as spin coating and dipping. can do. In the case of a copolymer, it is preferable to form a wet film after dissolving in a suitable solvent or the like. The film thickness is not particularly limited, but each layer needs to be set to an appropriate film thickness. If the film thickness is too thick, 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. Normal film thickness is from 5 nm to 10
The range of μm is suitable, but from 10 nm to 0.2
The range of μm is more preferable.

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

As described above, by using the compound of the general formula [1] in the organic EL device of the present invention, the electron transporting ability and the electron injection efficiency from the cathode surface are improved, and the light emission efficiency and the light emission brightness are increased. did it. Further, since the electron injection efficiency is high, it is very stable, and as a result, a high emission brightness can be obtained with a low driving current, so that the life, which has been a big problem until now, could be greatly reduced.

The organic EL device of the present invention can be used as a flat panel display such as a wall-mounted television or a flat luminous body.
It can be applied to light sources such as copiers and printers, light sources such as liquid crystal displays and instruments, display boards, marker lights, etc., and its industrial value is very large.

[0058]

The present invention will be described in more detail based on the following examples. Synthesis method of compound (1) 2.1 g of powdered 2- (2-hydroxyphenyl) benzoxazole was put in 200 ml of ethanol, and 65
Stir at ℃ to dissolve. After dissolution, 1.0 g of anhydrous zinc acetate was added and stirred at 65 ° C. for 3 hours, and the precipitated crystals were separated by filtration, washed with methanol and dried to give 1.9 g.
Was obtained. As a result of elemental analysis, molecular weight analysis and NMR spectrum analysis, it was confirmed to be the compound (1). Method for synthesizing compound (12) 2.3 g of powdered 2- (2-hydroxyphenyl) benzothiazole was put in 200 ml of ethanol and heated to 65 ° C.
Stir to dissolve. After dissolution, anhydrous zinc acetate 1.
0 g was added and the mixture was stirred at 65 ° C. for 3 hours, the precipitated crystals were separated by filtration, washed with methanol and dried to obtain 1.8 g of a yellow powder. As a result of elemental analysis, molecular weight analysis and NMR spectrum analysis, it was confirmed to be compound (12). Example 1 N, N '-(4-methylphenyl) -N, on a glass plate with an ITO electrode having a washed surface resistance value of 10 (Ω / □)
N '-(4-n-butylphenyl) -phenanthrene-
Dissolve 9,10-diamine in tetrahydrofuran,
A hole injection layer having a film thickness of 40 nm was obtained by spin coating. Then, a light-emitting layer having a thickness of 40 nm of tris (8-hydroxyquinoline) aluminum complex was formed, and the compound (1) was vacuum-deposited to form an electron injection layer having a thickness of 30 nm. An electrode having a thickness of 100 nm was formed from the mixed alloy to obtain an organic EL device. The light emitting layer and the electron injection layer were deposited at a substrate temperature of room temperature in a vacuum of 10 ⁻⁶ Torr. This element has a maximum brightness of 12,000 (cd / m ² ) at a DC voltage of 5 V and a luminance of 70 (cd / m ² ).
² ) Light emission with a luminous efficiency of 1.6 (lm / W) when 5 V was applied was obtained. Next, as a result of a life test in which the device was continuously made to emit light at a current density of 3 (mA / cm ² ), a light emission luminance of ½ or more of the initial luminance was maintained for 10,000 hours or more.

Example 2 Example 1 except that the compound (2) is used in the electron injection layer.
An organic EL device was produced in the same manner as in the above. This element
60 (cd / m ² ) at DC voltage 5V, maximum brightness 11,0
00 (cd / m ² ), luminous efficiency 1.7 when 5 V is applied
Light emission of (lm / W) was obtained. Next, 3 (mA / cm
As a result of a life test in which the device was made to continuously emit light at the current density of ² ), the emission brightness of ½ or more of the initial brightness was 10,
Held for over 000 hours.

Example 3 N, N'-diphenyl-N, N'-dinaphthyl-1,1-biphenyl-4,4 'was washed on a glass plate with an ITO electrode having a surface resistance value of 10 (Ω / □). -Diamine was vacuum-deposited to obtain a hole injection layer having a thickness of 40 nm. Then, tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited to form a light-emitting layer having a thickness of 40 nm, compound (5) is vacuum-deposited to form an electron-injection layer having a thickness of 30 nm, and magnesium and silver are added. An electrode having a thickness of 100 nm was formed from the alloy mixed at 10: 1 to obtain an organic EL element. The hole injection layer, the light emitting layer and the electron injection layer were deposited at a substrate temperature of room temperature in a vacuum of 10 ⁻⁶ Torr. This element has a DC voltage of 5 V, 70 (cd / m ² ), and a maximum brightness of 15,000.
0 (cd / m ² ), luminous efficiency at 5 V applied 1.8 (l
Light emission of m / W) was obtained. Next, as a result of a life test in which the device was continuously caused to emit light at a current density of 3 mA / cm ² , a light emission luminance of 1/2 or more of the initial luminance was maintained for 10,000 hours or more.

Example 4 A glass plate with an ITO electrode and N, N'-diphenyl-N,
Example 3 except that metal-free phthalocyanine is vacuum-deposited with N′-dinaphthyl-1,1-biphenyl-4,4′-diamine to form a hole injection layer having a film thickness of 5 nm.
An organic EL device was produced in the same manner as in the above. This element
110 (cd / m ² ) at DC voltage 5V, maximum brightness 14,
Luminous efficiency of 1.5 at 500 (cd / m ² ) and 5 V
Light emission of (lm / W) was obtained. Next, 3 mA / cm ²
As a result of a life test in which the device was made to continuously emit light at a current density of, the emission brightness of ½ or more of the initial brightness was 20,000.
It was kept for more than 0 hours.

Example 5 N, N'-diphenyl-N, N'-dinaphthyl-1,1-biphenyl-4,4 'was washed on a glass plate with an ITO electrode having a surface resistance value of 10 (Ω / □). -Diamine was vacuum-deposited to obtain a hole injection layer having a thickness of 40 nm. Then, tris (8-hydroxyquinoline) aluminum complex and quinacridone are vacuum-deposited at a weight ratio of 50: 1 to form a film having a thickness of 3
A 0 nm light emitting layer is formed, and the compound (12) is vacuum-deposited thereon to form an electron injecting layer having a thickness of 30 nm.
An electrode of 00 nm was formed to obtain an organic EL device. The hole injection layer, the light emitting layer, and the electron injection layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This element
1300 (cd / m ² ) at DC voltage 5V, maximum brightness 13
Luminous efficiency at 5,000 (cd / m ² ) and 5 V applied 1
A light emission of 2.7 (lm / W) was obtained. Next, 3mA /
As a result of a life test in which the device was continuously made to emit light at a current density of cm ^2, a luminance of ½ or more of the initial luminance was 2
Held for more than 000 hours.

Example 6 N, N'-diphenyl-N, N'-dinaphthyl-1,1-biphenyl-4,4 'was placed on a washed glass plate with an ITO electrode having a surface resistance value of 10 (Ω / □). -Diamine was vacuum-deposited to obtain a hole injection layer having a thickness of 40 nm. Then, the compound (A-8) in Table 2 is vacuum-deposited to form a light-emitting layer having a thickness of 40 nm, and the compound (22) is vacuum-deposited thereon to form an electron-injection layer having a thickness of 30 nm. Aluminum alloy with 100: 1 mixture of lithium and film thickness 100nm
Was formed to obtain an organic EL device. The hole injection layer, the light emitting layer, and the electron injection layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This element has a maximum luminance of 32,000 at a DC voltage of 5 V and a luminance of 420 (cd / m ² ).
(Cd / m ² ), luminous efficiency at 5 V applied 4.1 (lm
/ W). Next, as a result of a life test in which the device was continuously caused to emit light at a current density of 3 mA / cm ² , a light emission luminance of 1/2 or more of the initial luminance was maintained for 10,000 hours or more.

Example 7 N, N'-diphenyl-N, N'-dinaphthyl-1,1-biphenyl-4,4 'was washed on a glass plate with an ITO electrode having a surface resistance value of 10 (Ω / □). -Diamine was vacuum-deposited to obtain a hole injection layer having a thickness of 40 nm. Then, the compound (A-11) in Table 2 was vacuum-deposited to a film thickness of 40 nm.
And a compound (12) is vacuum-deposited thereon to form an electron injection layer having a film thickness of 30 nm, and an alloy in which aluminum and lithium are mixed at a ratio of 100: 1 has a film thickness of 100 n.
An electrode of m was formed to obtain an organic EL device. Hole injection layer,
The light emitting layer and the electron injection layer are in a vacuum of 10 ⁻⁶ Torr,
The deposition was performed at a substrate temperature of room temperature. This device has a direct current voltage of 5 V, 2500 (cd / m ² ), and a maximum brightness of 142,0.
00 (cd / m ² ), luminous efficiency under application of 5 V 14.6
Light emission of (lm / W) was obtained. Next, 3 mA / cm ²
As a result of a life test in which the device was made to continuously emit light at a current density of 1,500
It was kept for more than 0 hours.

Example 8 A compound (24) was vacuum-deposited on the light emitting layer to form a film having a thickness of 30.
Example 7 except that an electron-transporting layer having a thickness of 10 nm is formed, a tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited thereon to form an electron-injecting layer having a thickness of 10 nm, and the electron-injecting layer is laminated. An organic EL device was produced by the same method as described above. This element is 2200 (cd / m at a DC voltage of 5V).
² ), the maximum brightness was 135,000 (cd / m ² ), and blue light emission with a luminous efficiency of 13.4 (lm / W) when 5 V was applied was obtained. Next, as a result of a life test in which this device was continuously made to emit light at a current density of 3 mA / cm ² ,
A light emission brightness of 2 or more was maintained for 20,000 hours or more, and the light emission life was improved.

Example 9 Poly (2,5-dipentyl-p-phenylene vinylene)
Was dissolved in tetrahydrofuran, and an organic EL device was prepared in the same manner as in Example 7, except that a light emitting layer having a thickness of 40 nm was obtained by spin coating. This element has a maximum luminance of 26,50 at a DC voltage of 5 V and a luminance of 590 (cd / m ² ).
0 (cd / m ² ), luminous efficiency at the time of applying 5 V 4.0 (l
Light emission of m / W) was obtained. Next, as a result of a life test in which the device was continuously caused to emit light at a current density of 3 mA / cm ² , a light emission luminance of 1/2 or more of the initial luminance was maintained for 10,000 hours or more.

Example 10 An organic EL device was manufactured in the same manner as in Example 7, except that a cleaned PES film substrate with an ITO electrode having a surface resistance value of 15 (Ω / □) was used instead of the glass plate with an ITO electrode. Was produced. This element is 2200 (c
d / m ² ), maximum brightness 98,000 (cd / m ² ), 5
Light emission with a light emission efficiency of 15.3 (lm / W) when V was applied was obtained. Next, as a result of a life test in which this device was continuously made to emit light at a current density of 3 mA / cm ² ,
Emission brightness of 2 or more was maintained for 10,000 hours or more.

Comparative Example 1 2- (4'-tert-butylphenyl) -5- (4 "-biphenyl) -1,3,4-in place of the compound (12)
An organic EL device was produced in the same manner as in Example 7 except that oxadiazole was used. This device has a direct current voltage of 5V, 230 (cd / m ² ), and a maximum brightness of 20,500.
(Cd / m ² ), luminous efficiency at 5 V application of 2.2 (lm
/ W). Next, as a result of a life test in which the device was made to continuously emit light at a current density of 3 mA / cm ² , the emission brightness decreased to ½ or less of the initial brightness in 1100 hours.

Comparative Example 2 Instead of the compound (12), tris (8-hydroxyquinolin) was used.
N) Same as Example 7 except that aluminum complex is used
An organic EL device was manufactured in the same manner. This element is DC
1100 (cd / m at voltage 5V^Two), Maximum brightness 55,0
00 (cd / m ^Two) Luminous efficiency at 5 V applied 4.8
A green light emission of (lm / W) was obtained. Next, 3mA / c
m^TwoLifetime of continuous light emission of this device at current density of
As a result of the test, when the emission luminance is 1/2 or less of the initial luminance, 210
It decreased at 0 hours.

The organic EL device of the present invention achieves improvement of luminous efficiency, luminous brightness and prolongation of life, and is used together with a light emitting material, a doping material, a hole injecting material, an electron injecting material, and an increasing material. The sensitizer, the resin, the electrode material, and the like, and the element manufacturing method are not limited.

[0071]

According to the present invention, by using a compound having excellent electron transporting ability and good injection efficiency from the cathode in the electron injection layer, higher luminous efficiency, higher brightness and longer life can be obtained as compared with the prior art. An organic EL device was obtained. This is because the aggregation of the compound in the formed thin film is small,
This is probably because the device was prevented from deterioration and stable electron injection characteristics were obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunichi Onikubo 2-33 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd.

Claims (7)

[Claims] 1. An electron injection material for an organic electroluminescence device represented by the following general formula [1]. General formula [1] [In the formula, X, -O -, - S -, - NH -, - CH 2 -
Represents R ^{1 to} R ⁸ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, or a substituted or unsubstituted alkyl group. M represents a divalent or trivalent metal atom,
n represents 2 or 3. ] 2. An organic electroluminescence device comprising an organic compound thin film layer including a light emitting layer and an electron injection layer between a pair of electrodes, wherein the electron injection layer is the electron injection layer.
An organic electroluminescence device, which is a layer containing the electron injection material for an organic electroluminescence device described above. 3. The organic electroluminescence device according to claim 2, wherein the light emitting layer is a layer containing a metal complex compound. 4. The organic electroluminescence device according to claim 2, wherein the light emitting layer is a layer containing a compound represented by the following general formula [2]. General formula [2] [In the formula, Ar ¹ is an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom. R ^{9 to} R ¹² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aryl group which may have a nitrogen atom. ] 5. The organic electroluminescence device according to claim 2, wherein the light emitting layer is a layer containing a compound represented by the following general formula [3]. General formula [3] [In the formula, Ar ¹ is an arylene group which may contain a nitrogen atom, an oxygen atom or a sulfur atom. R ¹³ to R ¹⁴ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, an aryl group which may have a nitrogen atom of the substituted or unsubstituted. m represents an integer of 2 to 10,000. ] 6. The organic electroluminescence device according to claim 2, wherein the light emitting layer is a layer containing a compound represented by the following general formula [4]. General formula [4] [In the formula, B ^{1 to} B ⁴ each independently represent a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. G
Represents a substituted or unsubstituted arylene group. ] 7. The organic electroluminescence device according to claim 2, wherein a hole injection layer is provided.