JPH093448A - Electron transport material for organic electroluminescence device and organic electroluminescence device using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an electroluminescent device having high brightness, high emission efficiency, and little emission deterioration, and high reliability, by using an electron transport material having excellent electron transport properties and good injection efficiency from the cathode. With the goal. In an organic electroluminescence device including a light emitting layer or a layer composed of a plurality of organic compound thin films including a light emitting layer and an electron injecting layer between a pair of electrodes, the light emitting layer or the electron injecting layer is a compound represented by the general formula: An organic electroluminescence device comprising a layer containing the organic electroluminescence device material of [1]. General formula [1] [In the formula, R ^{1 to} R ⁴ each independently represent a hydrogen atom, an aliphatic group, an aliphatic cyclic group, a carbocyclic aromatic cyclic group, or a heterocyclic group. X ¹ and X ² are each independently an oxygen atom,
Represents a sulfur atom or a dicyanomethylene group. ]

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to pyrrolo [3,4-c].
A compound having a pyrrole skeleton is used for an electron injection layer of an organic electroluminescence (EL) element used for a flat light source or a light emitting display.

[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 transporting material of the organic layer of the organic EL device is preferably a material which has a high efficiency of injecting holes 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. The electron transporting material is preferably a material which has a high electron injection efficiency from the cathode and can efficiently transport 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 transporting materials proposed so far 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 the electron transport material, 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 property from the cathode to the organic layer of the organic EL device using this electron transport material was 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, in order to develop an organic EL device having higher luminous efficiency and long life, development of electron injection and electron transport materials is desired.

[0008]

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

[0009]

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

Embedded image [Wherein, R ^{1 to} R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted aliphatic cyclic group, a substituted or unsubstituted carbocyclic aromatic cyclic group Represents a substituted or unsubstituted heterocyclic group, X ¹ , X ²
Are each independently an oxygen atom, a sulfur atom or a dicyanomethylene group. ]

Furthermore, the present invention provides an organic electroluminescent device comprising a light emitting layer or a layer composed of a plurality of organic compound thin films including a light emitting layer and an electron injecting layer between a pair of electrodes, wherein the light emitting layer or the electron injecting layer is provided. Layers
It is an organic electroluminescent element, which is a layer containing the electron transporting material for an organic electroluminescent element.

Furthermore, the present invention is the above-mentioned organic electroluminescent device, further comprising a hole injection layer.

R ^{1 to} R ⁴ of the compound represented by the general formula [1] of the present invention are each independently a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted aliphatic cyclic group, It represents a substituted or unsubstituted carbocyclic aromatic ring group or a substituted or unsubstituted heterocyclic group. Specific examples of the aliphatic group include a methyl group, an ethyl group, a propyl group, a butyl group,
sec-butyl group, tert-butyl group, pentyl group,
Hexyl group, heptyl group, octyl group, stearyl group,
There are trichloromethyl groups and the like. Specific examples of the aliphatic ring group include a cyclohexyl ring and a methylcyclohexyl ring. Specific examples of the carbocyclic aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a 9,10-diphenylanthracene ring and a pyrene ring. Specific examples of the heterocycle include a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring,
Indole ring, carbazole ring, quinoline ring, isoquinoline ring, cinnoline ring, quinoxaline ring, pyrrolidine ring, piperidine ring, morpholine ring, piperazine ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring, benzoxazole Ring, benzothiazole ring, benzotriazole ring and the like.

Specific examples of the above-described ring substituents include chlorine, bromine, iodine, halogen atoms of fluorine, 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, trifluoromethyl group, 2,2,2-trifluoroethyl group, 2,2,3,3-tetrafluoropropyl group, 2,2,3,3,3 3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group, 2,2,3,3,4,4-hexafluorobutyl group, 2-methoxyethyl group, etc. A substituted or unsubstituted aliphatic group, a cyclopentane group, a substituted or unsubstituted aliphatic ring group such as a cyclohexyl group, a phenyl group, a naphthyl group, a biphenyl group, an anthranyl group, a 3-methylphenyl group, a 3-methoxyphenyl group, 3-fluorophenyl group, 3-trichloromethylphenyl group, 3-trifluoromethylphenyl group, 3-nitrophenyl group, p-t
-Butylphenyl group, substituted or unsubstituted carbocyclic aromatic ring 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-
Substituted or unsubstituted alkoxy group such as propoxy group, 6- (perfluoroethyl) hexyloxy group, phenoxy group, p-nitrophenoxy group, p-tert-butylphenoxy group, 3-fluorophenoxy group, pentafluorophenyl group A substituted or unsubstituted aryloxy group such as 3-trifluoromethylphenoxy group, a methylthio group, an ethylthio group, a tert-butylthio group, a hexylthio group, an octylthio group, a substituted or unsubstituted alkylthio group such as a trifluoromethylthio group, A substituted or unsubstituted arylthio group such as phenylthio group, p-nitrophenylthio group, p-tert-butylphenylthio group, 3-fluorophenylthio group, pentafluorophenylthio group, 3-trifluoromethylphenylthio group, Cyano group B group, amino group, 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, bisacetoxypropyl ) 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, butylcarbamoyl group, phenyl Carbamoyl group such as carbamoyl group, carboxylic acid group, sulfonic acid group, imide group, pyridine group, pyrazine group, pyrimidine group, pyridazine group,
Heterocyclic groups such as triazine group, indole group, quinoline group, acridine group, pyrrolidine group, dioxane group, piperidine group, morpholine group, piperazine group and trithiane group.

Pyrrolo [3,4-represented by the general formula [1]
Examples of the c] pyrrole compound include those described in JP-A-58-2100.
It is synthesized by the method described in JP-A No. 84 and JP-A-59-24758.

Hereinafter, typical examples of the compounds of the present invention are specifically shown in Table 1, but the present invention is not limited to the following typical examples.

[0016]

[Table 1]

[0017]

[0018]

[0019]

[0020]

The compound represented by the general formula [1] of the present invention may be used alone or in a mixture in the same layer.
Further, it may be used in a mixture with another hole or electron transporting compound. Since the compound of the present invention has a large electron transporting ability and electron injecting ability from the cathode,
It can be used very effectively in the electron injection layer of the L element.

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 contains a light emitting material, and may further contain a hole transporting material or an electron transporting material for transporting holes injected from the anode or electrons injected from the 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 transporting material of 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 transporting material or an electron transporting 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 transporting 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 in the light emitting layer itself has a hole transporting property or that the hole transporting 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, 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 an element having a multilayer structure, a light emitting material, a doping material, a hole transport material for transporting carriers, and an electron transport material can be used in combination, if necessary.
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.

The conductive material used for the anode is 4
A metal having a work function larger than eV is suitable, and A
u, Pt, Ag, Cu and other metals, metal alloys, ITO, N
An organic conductive resin such as ESA or polythiophene or polypyrrole is used.

The conductive material used for the cathode is 4
A metal or metal alloy having a work function smaller than eV is suitable. As the material, Al, In, Mg, L
metal such as i, or Mg / Ag, Li / Al, Mg
An alloy such as / In may be used. The anode and the cathode may be formed of two or more layers if necessary. The anode and the cathode are produced by a known film forming method.

In the organic EL device, at least one of the cathode and the anode is preferably made 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-mentioned conductive material so as to ensure a predetermined translucency by a method such as vapor deposition or sputtering.
The light transmittance of the electrode on the light emitting surface side is desirably 10% or more.

The substrate may be a transparent one having mechanical and thermal strength, and examples thereof include a transparent resin such as a glass substrate, a polyethylene plate, a polyether sulfone plate and a polypropylene plate.

For forming each layer of the organic EL device of the present invention, any method such as a dry film forming method such as vacuum deposition and sputtering, or a wet film forming method such as spin coating and dipping can be applied. 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. The normal film thickness is preferably in the range of 5 nm to 10 μm, more preferably in the range of 10 nm to 0.2 μm.

In the case of the wet film forming method, the material forming each layer is dissolved or dispersed in a solvent such as chloroform, tetrahydrofuran, dioxane 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.

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 transporting materials and electron transporting materials are used. 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.

The hole-transporting material that can be used in the organic EL device of the present invention has the ability to transport holes, has an excellent hole-injecting effect to the light-emitting layer or the light-emitting material, and is produced in the light-emitting layer. 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-transporting material that can be used in the organic EL device of the present invention has the ability to transport electrons, has an excellent electron-injecting effect on the light-emitting layer or the light-emitting substance, and excitons generated in the light-emitting layer. Examples of the compound include a compound capable of preventing the transfer of the compound to the hole injection layer or the hole transport material and having an excellent thin film forming ability. Examples include, but are not limited to, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxadiazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane, anthrone, and derivatives thereof. Not something. It is also possible to sensitize by adding an electron accepting substance to the hole transporting material and adding an electron donating substance to the electron transporting 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 addition to the compound of the general formula [1], at least one of a light emitting material, a doping material, a hole transporting material and an electron transporting material may be contained in the same layer. Further, in order to improve the stability of the organic EL device obtained by the present invention against temperature, humidity, atmosphere, etc., a protective layer may be provided on the surface of the device,
It is also possible to encapsulate silicon oil or the like to protect the entire device.

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.

[0038]

The present invention will be described in more detail based on the following examples. Example 1 The compound (1
3), tris (8-hydroxyquinoline) aluminum complex, N, N '-(4-methylphenyl) -N, N'-
(4-n-Butylphenyl) -phenanthrene-9,1
0-diamine and a polycarbonate resin (Teijin Kasei: Panlite L-1250) were dissolved in tetrahydrofuran at a ratio of 1: 3: 2: 5, and a light emitting layer having a thickness of 100 nm was obtained by a spin coating method. On top of that, an alloy in which magnesium and silver are mixed in a ratio of 10: 1 has a film thickness of 150 n.
An electrode of m was formed to obtain an organic EL device. This element
Light emission of 120 cd / m ² was obtained at a DC voltage of 5 V. 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 luminance of ½ or more of the initial luminance was maintained for 1000 hours or more.

Comparative Example 1 An organic EL device was prepared in the same manner as in Example 1 except that the compound (13) was not used. With this device, light emission of 65 cd / m ² was obtained at a DC voltage of 5 V. As a result of the same life test as in Example 1, the luminance deteriorated to half or less of the initial luminance in 30 hours.

Example 2 On a cleaned glass plate with an ITO electrode, N, N '-(4
-Methylphenyl) -N, N '-(4-n-butylphenyl) -phenanthrene-9,10-diamine was dissolved in tetrahydrofuran, and a hole injection layer having a thickness of 50 nm was obtained by spin coating. Then Tris (8-
Hydroxyquinoline) aluminum complex and compound (5)
Is vacuum-deposited at a ratio of 3: 1 to form a light-emitting layer having a film thickness of 30 nm, and an electrode having a film thickness of 100 nm is formed on the light-emitting layer having a thickness ratio of 10: 1 to form an organic EL device. Obtained. The hole injection layer and the light emitting layer were deposited at a substrate temperature of room temperature in a vacuum of 10 ⁻⁶ Torr. This device emitted light of 500 cd / m ² at a DC voltage of 5V. 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, a luminance of ½ or more of the initial luminance was retained for 1000 hours or more.

Comparative Example 2 An organic EL device was prepared in the same manner as in Example 2 except that the compound (5) was not used. This element has a DC voltage of 5
Light emission of 110 cd / m ² was obtained at V. As a result of the same life test as in Example 2, the luminance deteriorated to ½ or less of the initial luminance in 100 hours.

Example 3 N, N '-(4
-Methylphenyl) -N, N '-(4-n-butylphenyl) -phenanthrene-9,10-diamine was vacuum-deposited to obtain a hole injection layer having a film thickness of 20 nm. Then, a tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited to form a light emitting layer having a film thickness of 30 nm.
4) was vacuum-deposited to form an electron injection layer having a film thickness of 30 nm, and an electrode having a film thickness of 100 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic EL device. The hole injection layer and the light emitting layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This element has a DC voltage of 5
Light emission of 600 cd / m ² was obtained at V. Next, 3mA
As a result of a life test in which the device was continuously lit at a current density of / cm ² , a luminescence brightness of 1/2 or more of the initial brightness was 1
Held for over 000 hours.

Example 4 ~ The compounds shown in Table 2 were used in place of the compound (24),
An organic EL device was produced in the same manner as in Example 3 except that the electron injection layer having a thickness of 30 nm was formed by vacuum vapor deposition. Table 2 shows the emission luminance of each organic EL element.
Next, as a result of a life test in which these devices were made to continuously emit light at a current density of 3 mA / cm ² , in all devices, the emission brightness of ½ or more of the initial brightness was maintained for 1000 hours or more.

[0044]

[Table 2]

Examples 15 to 27 The compounds shown in Table 3 were used in place of the compound (24),
An organic EL device was produced in the same manner as in Example 3, except that the electron injection layer having a film thickness of 30 nm was obtained by dissolving in ethanol and performing spin coating. Each organic EL
Table 2 shows the emission luminance of the device. Next, as a result of a life test in which these devices were made to continuously emit light at a current density of 3 mA / cm ² , in all devices, the emission brightness of ½ or more of the initial brightness was maintained for 1000 hours or more.

[0046]

[Table 3]

Comparative Example 3 An organic EL device was prepared in the same manner as in Example 3 except that the compound (24) was not used. With this device, light emission of 150 cd / m ² was obtained at a DC voltage of 5V. As a result of the same life test as in Example 3, the initial luminance was ½ of 100 hours after 100 hours.
It deteriorated to the following.

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

[0049]

According to the present invention, by using a compound having an excellent electron transporting ability and a good injection efficiency from the cathode for the electron injection layer or the light emitting layer, the light emitting efficiency and the brightness are higher than those of the conventional ones. An organic EL device having a long life could be obtained. Further, since a solubilizing substituent is introduced into the phthalocyanine nitrogens themselves, the phthalocyanine nitrogen becomes soluble in an organic solvent and a thin uniform film can be formed by coating. Also, since it has high solubility in organic solvents such as alcohols,
It has become possible to form a required thin film without melting or eroding the lower layer when stacking the organic thin films. Further, the vapor-deposited film can also prevent the element from deteriorating by preventing agglomeration after the thin film is formed, and stable electron transport characteristics can be obtained.

[Procedure amendment]

[Submission date] July 21, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction contents]

Examples 4 to 17 The compounds shown in Table 2 were used in place of the compound (24),
An organic EL device was produced in the same manner as in Example 3 except that the electron injection layer having a thickness of 30 nm was formed by vacuum vapor deposition. Table 2 shows the emission luminance of each organic EL element.
Next, as a result of a life test in which these devices were made to continuously emit light at a current density of 3 mA / cm ² , in all devices, the emission brightness of ½ or more of the initial brightness was maintained for 1000 hours or more.

[Procedure amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction contents]

Examples 18 to 24 The compounds shown in Table 3 were used in place of the compound (24),
An organic EL device was produced in the same manner as in Example 3, except that the electron injection layer having a film thickness of 30 nm was obtained by dissolving in ethanol and performing spin coating. Each organic EL
Table 2 shows the emission luminance of the device. Next, as a result of a life test in which these devices were made to continuously emit light at a current density of 3 mA / cm ² , in all devices, the emission brightness of ½ or more of the initial brightness was maintained for 1000 hours or more.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction contents]

[0049]

According to the present invention, by using a compound having an excellent electron transporting ability and a good injection efficiency from the cathode for the electron injection layer or the light emitting layer, the light emitting efficiency and the brightness are higher than those of the conventional ones. An organic EL device having a long life could be obtained.

Claims (3)

[Claims] 1. An electron transport material for an organic electroluminescence device represented by the following general formula [1]. General formula [1] [Wherein, R ^{1 to} R ⁴ are each independently a hydrogen atom, a substituted or unsubstituted aliphatic group, a substituted or unsubstituted aliphatic cyclic group, a substituted or unsubstituted carbocyclic aromatic cyclic group Represents a substituted or unsubstituted heterocyclic group, X ¹ , X ²
Are each independently an oxygen atom, a sulfur atom or a dicyanomethylene group. ] 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 injecting layer between a pair of electrodes, wherein the light emitting layer or the electron injecting layer is formed. An organic electroluminescence device comprising a layer containing an electron transport material for an organic electroluminescence device. 3. The organic electroluminescence device according to claim 2, further comprising a hole injection layer.