JPH09272865A - Electron injection material for organic electroluminescence device and organic electroluminescence device using the same - Google Patents

Abstract

(57) [Abstract] (Correction) [Problem] Electroluminescence (EL) device having high brightness, high emission efficiency, and low emission degradation and high reliability by an electron injection material having good electron transporting property and injection efficiency from cathode. I will provide a. An electron injection material for an organic EL device represented by the general formula 1,
And an organic EL device having a layer composed of a plurality of organic compound thin films including a light emitting layer or 1 and an electron injection layer between a pair of electrodes, wherein the electron injection layer contains the organic EL device material. [A and R ^{1 to} R ⁵ are independently hydrogen, halogen, substituted 1-unsubstituted alkoxy group, amino group, alkyl group, cycloalkyl group, aryl group that may have a nitrogen atom, or nitrogen atom. It represents a good aryloxy group (provided that A is not hydrogen), and adjacent substituents R ^{1 to} R ⁵ may be bonded to each other to form an aromatic ring which may contain nitrogen. M is 2
~ A tetravalent metal atom, and n represents an integer of 2 to 4. ]

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron injecting material for an organic electroluminescence (EL) element used for a flat light source or a light emitting display and a light emitting element having high brightness 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. In 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. Further, the electrons are recombined with holes 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, a metal chelate complex is laminated as a phosphor layer and an amine compound is laminated as a hole injecting layer to obtain high-luminance green light emission, and the luminance is several hundred at a DC voltage of 6 to 7V.
It has cd / m ² and a maximum luminous efficiency of 1.5 lm / W, which is close to the practical range.

The hole injection material for the organic layer of the organic EL element is preferably a material which has a good hole injection efficiency from the anode and can efficiently transport 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 to have high electron affinity, high electron mobility, and excellent stability.

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 an electron injection material having excellent electron transporting ability and having durability, and further using the electron injection material, high brightness and long brightness. It is an object to provide a long-life organic EL device. As a result of earnest studies by the present inventors, organic E using at least one electron injection material represented by the general formula [1]
The present inventors have found that the L element has a large electron injection capability and excellent life stability upon repeated use, and has completed 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].

[In the formula, A and R ^{1 to} R ⁵ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, It represents a substituted or unsubstituted cycloalkyl group, an aryl group which may have a substituted or unsubstituted nitrogen atom, or an aryloxy group which may have a substituted or unsubstituted nitrogen atom. However, A does not include a hydrogen atom. Here, the adjacent substituents R ^{1 to} R ⁵ may be bonded to each other to form an aromatic group which may contain a nitrogen atom. M represents a divalent or tetravalent metal atom, and n represents a positive integer of 2 to 4. ] General formula [1]

Embedded image

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

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

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

Embedded image [Wherein Ar ¹ is selected from C, N, H, O and S 1
It is a divalent linking group consisting of a chemically rational combination composed of ˜100 atoms. R ^{6 to} R ⁹ each independently represent 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. ]

Further, the present invention is the organic electroluminescent 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]

[Chemical 6] [Wherein Ar ¹ is selected from C, N, H, O and S 1
It is a divalent linking group consisting of a chemically rational combination composed of ˜100 atoms. R ^{6 to} R ⁹ each independently represent 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. n represents a positive integer of 2 or more and 10000 or less. ]

Furthermore, the present invention is the above-mentioned organic electroluminescent device, characterized in that a hole injection layer is provided between the anode and the light emitting layer.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A or R ^{1 to} R ⁵ 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 A substituted amino group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, an aryl group which may have a substituted or unsubstituted nitrogen atom, or a substituted or unsubstituted nitrogen atom Represents a good aryloxy group. However, A is not a hydrogen atom.

Specific examples of the halogen atom include fluorine,
There are 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,
There are a dimethylamino group, a diethylamino group, a diphenylamino group, a ditolylamino group, an N-naphthyl-1-phenylamino group and the like. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group,
There are heptyl group, octyl group, stearyl group, trichloromethyl group and the like. Specific examples of the cycloalkyl group include:
Examples thereof include a cyclohexyl group and a methylcyclohexyl group.
Specific examples of the aryl group which may have a nitrogen atom include:
Phenyl group, naphthyl group, anthranyl group, phenanthrenyl group, 9,10-diphenylanthranyl group, pyrenyl group, pyridyl group, pyridazyl group, pyrimidyl group, pyrazyl group, triazyl group, indolyl group, carbazolyl group, quinolyl group, isoquinolyl group, Cinnolyl group, quinoxalyl group, pyrrolidyl group, piperidyl group, morpholyl group, piperazyl group, oxazolyl group, thiazolyl group,
Examples thereof include triazolyl group, oxadiazolyl group, thiadiazolyl group, benzoxazolyl group, benzothiazolyl group and benzotriazolyl group. Specific examples of the aryloxy group which may have a nitrogen atom include a phenoxy group and 4-
Phenylphenoxy group, 4-phenoxyphenoxy group,
There are pyridyloxy groups and the like.

Specific examples of the substituent which may be added to the above-mentioned groups include halogen atoms of fluorine, chlorine, bromine and iodine, methyl, ethyl, propyl, butyl, 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 -Substituted or unsubstituted alkyl group such as propyl group, 2,2,3,3,4,4-hexafluorobutyl group and 2-methoxyethyl group, substituted or unsubstituted cyclo group such as cyclopentane group and cyclohexyl group Alkyl group, phenyl group, naphthyl group, biphenyl group, anthranyl group, 3-methylphenyl group, 3-methoxyphenyl group,
3-fluorophenyl group, 3-trichloromethylphenyl group, 3-trifluoromethylphenyl group, 3-nitrophenyl group, p-t-butylphenyl group, substituted or unsubstituted aryl group such as pentafluorophenyl 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-hexa Fluoro-2-propoxy group, 6- (perfluoroethyl)
Substituted or unsubstituted alkoxy group such as hexyloxy group, phenoxy group, p-nitrophenoxy group, p-te
substituted or unsubstituted aryloxy groups such as rt-butylphenoxy group, 3-fluorophenoxy group, pentafluorophenyl group, 3-trifluoromethylphenoxy group, methylthio group, ethylthio group, tert-butylthio group, hexylthio group, octylthio Group, substituted or unsubstituted alkylthio group such as trifluoromethylthio group, phenylthio group, p-nitrophenylthio group, p-
a substituted or unsubstituted arylthio group such as a tert-butylphenylthio group, a 3-fluorophenylthio group, a pentafluorophenylthio group, a 3-trifluoromethylphenylthio group, a cyano group, a nitro group, an amino group, and a methylamino group Mono- or di-substituted amino groups such as diethylamino group, ethylamino group, diethylamino group, dipropylamino group, dibutylamino group, diphenylamino group, bis (acetoxymethyl) amino group, bis (acetoxyethyl) amino group, bisacetoxy Propyl) amino group, acylamino group such as bis (acetoxybutyl) amino group, hydroxyl group, siloxy group, acyl group, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl group, propylcarbamoyl group, butylcarbamo Group, a carbamoyl group such as phenylcarbamoyl group, a carboxylic acid group, sulfonic acid group,
Heterocyclic groups such as imide group, pyridine group, pyrazine group, pyrimidine group, pyridazine group, triazine group, indole group, quinoline group, acridine group, pyrrolidine group, dioxane group, piperidine group, morpholine group, piperazine group, etc. . Here, R ¹ to R ⁵ may be bonded to each other by adjacent substituents to form an aromatic ring which may contain a nitrogen atom.

In the general formula [1], M represents beryllium, zinc, cadmium, magnesium, calcium, cobalt, nickel, iron, copper, strontium, scandium, aluminum, gallium, indium, yttrium or zirconium. It 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, 3 in the case of a trivalent metal, and 4 in the case of a tetravalent 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.

[0021]

[Table 1]

[0022]

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.

In the light emitting layer, if necessary, a light emitting material, a doping material, a hole injecting material or an electron injecting material can be used in addition to the compound of the general formula [1] of the present invention. 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.

Further, 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, by forming the organic EL element into a multi-layer structure, it is possible to prevent a decrease in brightness and life due to quenching. In such a device having a multi-layer 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.
The hole injection layer, the light emitting layer, and the electron injection layer may each 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 Materials can also be used.

Known luminescent 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.

As the light emitting material suitable for the electron injecting material of the present invention, a metal complex compound, a compound of the general formula [2], or a light emitting layer having 1 to 1 selected from C, N, H, O and S is used.
Examples of the conjugated polymer include a repeating unit composed of a divalent linking group and / or a vinyl group, which is composed of a chemically rational combination of 00 atoms. As the metal complex compound, (8-hydroxyquinolinonato)
Lithium, bis (8-hydroxyquinolinonato) zinc,
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-phenolato) aluminum, bis (2
-Methyl-8-quinolinato) (1-phenolato) 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.

Further, a general formula suitable as a light emitting material
Ar of the compound represented by [2]¹As C, N,
Consists of 1 to 100 atoms selected from H, O, S
A divalent linking group consisting of a chemically rational combination of
Just do it. As a specific linking group, even if it has a substituent
Good phenylene group, naphthylene group, biphenylene group, a
Intranylene group, pyrenylene group, thiophenylene group,
Such as a Riphenylamino group and N-ethylcarbazole group
However, the present invention is not limited to these. these
As the substituent, a compound represented by the above general formula [1]
A or R¹~ R ^FiveThe same substituents as can be mentioned.
R⁶~ R⁹Are independently substituted or unsubstituted
An alkyl group, a substituted or unsubstituted cycloalkyl group,
Aryl which may have a substituted or unsubstituted nitrogen atom
And a substituent added to them is R¹~ R
^FiveThe same substituents as can be mentioned. In addition, alkyl group,
Aryl which may have a chloroalkyl group or a nitrogen atom
R is R¹~ R^FiveGroups similar to those represented by
You.

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.

[0032]

[Table 2]

Further, as a compound suitable as a light emitting material, a divalent linkage consisting of a chemically rational combination composed of 1 to 100 atoms selected from C, N, H, O and S is used. There are conjugated polymers composed of repeating units with groups and / or vinyl groups. The divalent linking group may be the same linking group as Ar ¹ . Examples of the substituent of these linking groups include the same substituents as A or R ^{1 to} R ^{5 of the} compound represented by the above general formula [1]. Repeating unit is 2 or more and 100,000
It is as follows. 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-phenylenevinylene), poly (2,5-
Dioctyl-p-phenylenevinylene), poly (2.5)
-Dihexyloxy-p-phenylenevinylene), poly (2,5-dihexyloxy-m-phenylenevinylene), poly (2,5-dihexylthio-p-phenylenevinylene), 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-thienylenevinylene),
Poly (1,4-naphthalenevinylene), poly (9,10
-Anthracene vinylene) and their copolymers. These compounds may be used alone or as a mixture of two or more.

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. Examples include, but are not limited to, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxadiazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane, anthrone, and derivatives thereof. Not something. 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 the organic EL device, at least one of the cathode and the anode is preferably 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 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

For forming each layer of the organic EL device of the present invention, any one of dry film forming methods such as vacuum deposition, sputtering, ion plating, and plasma gun method, and wet film forming methods such as spin coating and dipping is applied. 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 light-emitting 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.

[0045]

The present invention will be described in more detail based on the following examples. 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. Next, a light-emitting layer of tris (8-hydroxyquinoline) aluminum complex having a thickness of 40 nm was formed, and the compound (2) 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 device has a DC voltage of 5 V, 50 (cd / m ² ), and a maximum brightness of 11,000 (cd / m ² ).
² ) Green light emission with a luminous efficiency of 1.0 (lm / W) when 5 V was applied was obtained. Next, as a result of a life test of continuously emitting light from this device at a current density of 3 (mA / cm ² ),
Luminance of at least ½ of the initial luminance was maintained for 10,000 hours or more.

Example 2 Example 1 except that the compound (4) is used in the electron injection layer.
An organic EL device was produced in the same manner as in the above. This element
65 (cd / m ² ) at 5V DC voltage, maximum brightness of 12,0
00 (cd / m ² ), luminous efficiency when applying 5 V 1.2
Green light emission of (lm / W) was obtained. Next, 3 (mA /
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 1 or more of the initial luminance was 1 or less.
Held for more than 000 hours.

Example 3 A cleaned glass electrode with an ITO electrode having a surface resistance value of 10 (Ω / □)
N, N'-diphenyl-N, N'-dinaf on a lath plate
Vacuum the chill-1,1-biphenyl-4,4'-diamine.
By vapor deposition, a hole injection layer having a film thickness of 40 nm was obtained. Then
Tris (8-hydroxyquinoline) aluminum complex
It is vacuum-deposited to form a light emitting layer with a thickness of 40 nm.
(4) is vacuum-deposited to form an electron injection layer with a thickness of 30 nm.
And a film thickness of 10: 1 alloy of magnesium and silver
An 100 nm electrode was formed to obtain an organic EL device. Hole
The injection layer, the light emitting layer, and the electron injection layer are 10^-6Torr
The substrate was vapor-deposited at room temperature in vacuum. This element is
75 (cd / m at flow voltage 5 V ^Two), Maximum brightness 14,50
0 (cd / m^Two) Luminous efficiency at 5 V applied 1.3 (l
m / W) green emission was obtained. Next, 3 mA / cm^Two
Life test with this device emitting continuous light at current density of
As a result, the emission luminance of 1/2 or more of the initial luminance is 10,000
It was kept for more than 0 hours.

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
100 (cd / m ² ) at a DC voltage of 5 V, maximum brightness of 12,
Luminous efficiency of 1.0 at 500 (cd / m ² ) and 5V
Green light emission of (lm / W) was obtained. Next, 3mA / c
As a result of a life test in which the device was made to continuously emit light at a current density of m ² , as a result, the emission brightness of ½ or more of the initial brightness was 20,
Held for over 000 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 were vacuum-deposited at a weight ratio of 50: 1 to form a light-emitting layer having a thickness of 30 nm, and compound (5) was vacuum-deposited thereon to form a light-emitting layer having a thickness of 30 nm. An electron injection layer is created, and the film thickness is 1 with an alloy in which aluminum and lithium are mixed at 100: 1.
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
1200 (cd / m ² ) at a DC voltage of 5V, maximum brightness of 10
Luminous efficiency at 5,000 (cd / m ² ) and 5 V applied 1
A green emission of 0.1 (lm / W) was obtained. Next, 3m
As a result of a life test in which the device was continuously made to emit light at a current density of A / cm ^2, a luminance of ½ or more of the initial luminance was retained for 20,000 hours or more.

Example 6 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-3) in Table 2 was vacuum-deposited to a film thickness of 40 nm.
And a compound (5) 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 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 device has a direct current voltage of 5 V, 500 (cd / m ² ), and a maximum brightness of 25,000.
(Cd / m ² ), luminous efficiency at 5 V application of 2.2 (lm
/ W) blue light emission 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 luminance of ½ or more of the initial luminance was 10,000.
Held for more than an hour.

Example 7 Example 6 was repeated except that the compounds (A-3) and (A-2) shown in Table 2 were vacuum deposited at a weight ratio of 5: 1 to form a light emitting layer having a thickness of 40 nm. An organic EL device was produced by the same method.
This element is 1500 (cd / m ² ) at DC voltage 5V,
Blue light emission with a maximum luminance of 45,000 (cd / m ² ) and a light emission efficiency of 5.3 (lm / W) when 5 V was applied was obtained. 3
As a result of a life test in which the device was continuously made to emit light at a current density of mA / cm ^2, a luminance of ½ or more of the initial luminance was retained for 10,000 hours or more.

Example 8 An organic EL device was produced in the same manner as in Example 6 except that the hole injection layer was not provided. This device has a direct current voltage of 5 V, 320 (cd / m ² ), and a maximum brightness of 19,000 (cd / m ² ).
m ² ), blue light emission with a luminous efficiency of 1.7 (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 retained for 8,000 hours or more.

Example 9 Poly (2,5-dipentyl-p-phenylene vinylene)
Was dissolved in tetrahydrofuran, and an organic EL device was produced by the same method as in Example 6 except that a light emitting layer having a thickness of 40 nm was obtained by spin coating. This element has a DC voltage of 5 V and a luminance of 650 (cd / m ² ) and a maximum luminance of 27,000.
0 (cd / m ² ), luminous efficiency at the time of applying 5 V 3.1 (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 produced in the same manner as in Example 6 except that the hole injection layer was not provided. This device has a DC voltage of 5 V and a maximum luminance of 15,000 (cd / m ² 440 (cd / m ² )).
m ² ), light emission with a light emission efficiency of 1.3 (lm / W) when applying 5 V was obtained. Next, at a current density of 3 mA / cm ² ,
As a result of a life test in which this device was made to emit light continuously, a light emission luminance of ½ or more of the initial luminance was maintained for 10,000 hours or more.

Example 11 N, N, N ′, N ′-(4-methylphenyl) -anthracene-9,10-diamine was vacuum-deposited to a film thickness of 40 n.
An organic EL device was produced in the same manner as in Example 6 except that the light emitting layer of m was produced. This element has a DC voltage of 5V
100 (cd / m ² ), maximum brightness 85,000 (cd /
m ² ), green light emission with an emission efficiency of 9.3 (lm / W) when 5 V was applied 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 20,000 hours or more.

Example 12 An organic EL device was manufactured in the same manner as in Example 11 except that a washed PET 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 device has a DC voltage of 5V and 2000
(Cd / m ² ), maximum brightness 79,000 (cd /
m ² ), luminous efficiency at 5V application of 12.3 (lm / 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.

Examples 13 to 24 Using the compounds shown in Table 3 in place of the compound (5),
Other than forming an electron injection layer with a thickness of 30 nm by vacuum evaporation
In the same manner as in Example 6, an organic EL device was manufactured.
Table 2 shows the emission luminance of each organic EL element. Next
To 3 mA / cm ^TwoThese elements are connected continuously at a current density of
As a result of the life test of emitting light,
Luminance of 1/2 or more of the initial luminance is 10,000 hours or less
Held on.

[0058]

[Table 3]

Comparative Example 1 Example 1 was repeated except that 2- (4'-tert-butylphenyl) -5- (4 "-biphenyl) -1,3,4-oxadiazole was used instead of the compound (5). An organic EL device was produced in the same manner as in Example 11. The device had a maximum brightness of 19,500 at a DC voltage of 5 V of 220 (cd / m ² ).
(Cd / m ² ), luminous efficiency at 5 V application 2.3 (lm
/ W) green light emission 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 , the emission brightness was reduced to ½ or less of the initial brightness in 1200 hours.

Comparative Example 2 An organic EL device was produced in the same manner as in Example 11 except that tris (8-hydroxyquinoline) aluminum complex was used instead of the compound (5). This device has a DC voltage of 5 V and a luminance of 520 (cd / m ² ) and a maximum brightness of 27,0.
00 (cd / m ² ), luminous efficiency at 5V application of 2.8
Green light emission of (lm / W) was obtained. Next, 3mA / c
As a result of a life test in which the device continuously emits light at a current density of m ² , it was found that the emission brightness was 330% or less of the initial brightness.
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.

[0062]

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.

Claims (6)

[Claims] 1. An electron injection material for an organic electroluminescence device represented by the following general formula [1]. General formula [1] [In the formula, A and R ^{1 to} R ⁵ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted It represents a substituted cycloalkyl group, an aryl group which may have a substituted or unsubstituted nitrogen atom, or an aryloxy group which may have a substituted or unsubstituted nitrogen atom (provided that A is not a hydrogen atom. ) And adjacent substituents of R ^{1 to} R ⁵ may be bonded to each other to form an aromatic ring which may contain a nitrogen atom.
M represents a divalent or tetravalent metal atom, and n represents an integer of 2 to 4. ] 2. An organic electroluminescence device comprising a light emitting layer or 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 organic electroluminescence device according to claim 1. An organic electroluminescence device, which is a layer containing an electron injection material for use. 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] [Wherein Ar ¹ is selected from C, N, H, O and S 1
It is a divalent linking group consisting of a chemically rational combination composed of ˜100 atoms. R ^{6 to} R ⁹ each independently represent 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] [Wherein Ar ¹ is selected from C, N, H, O and S 1
It is a divalent linking group consisting of a chemically rational combination composed of ˜100 atoms. R ^{6 to} R ⁹ each independently represent 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. n represents a positive integer of 2 or more and 10000 or less. ] 6. The organic electroluminescence device according to claim 2, wherein a hole injection layer is provided between the anode and the light emitting layer.