JP2002216970A - Organic electric field light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element easily manufactured in which a luminance is high and a stable performance is offered even if it is repeatedly used. SOLUTION: In the electric field light-emitting element composed of a single or plural organic compound layers pinched between a pair of electrodes at least either of which is transparent or translucent, this comprises that at least one layer of the organic compound layer contains at least one kind of compound expressed in a formula (I). In addition, X in the formula (I) represents a group selected among a structural group 1 shown in a formula (II), and a cyclic atom group consisting of A and two carbon atoms and a cyclic atom group consisting of B and two carbon atoms respectively represent structures individually selected among a structural group 2 shown in a formula (III).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device (hereinafter, referred to as "organic EL device") which emits light by converting electric energy into light, and relates to a display device, a backlight,
The present invention relates to an organic electroluminescent element that can be suitably used in fields such as an illumination light source, an exposure apparatus for electrophotography, a sign, and a sign.

[0002]

2. Description of the Related Art An EL element is a self-luminous all-solid-state element and has high visibility and resistance to impact, so that it is widely expected to be applied. At present, inorganic phosphors are mainly used. However, since an AC voltage of 200 V or more is required for driving, there are problems such as high production cost and insufficient luminance.

[0003] On the other hand, research on EL devices using organic compounds started with single crystals such as anthracene.
In the case of a single crystal, the film thickness was as thick as about 1 mm, and a driving voltage of 100 V or more was required. For this reason, thinning by an evaporation method has been attempted (Thin Solid Films,
Vol. 94, 171 (1982)). In an organic EL device, when electrons are injected from one of the electrodes and holes are injected from the other electrode, the luminescent material in the device is excited to a high energy level, and the excited luminescent material is in a ground state. Light is emitted based on the phenomenon that extra energy is emitted as light when returning to. However, the thin-film device obtained by this method still has a high driving voltage of 30 V,
Sufficient luminance was not obtained because the density of electron / hole carriers in the film was low and the probability of photon generation due to carrier recombination was low.

In recent years, however, in a function-separated type EL device in which a thin film of a hole-transporting organic low-molecular compound and a fluorescent organic low-molecular compound having an electron-transporting property are sequentially laminated by a vacuum deposition method, a voltage of about 10 V is applied. It has been reported that high luminance of 1000 cd / m ² or more can be obtained (App.
l. Phys. Lett. , Vol. 51, 913
(1987)) Since then, research and development of organic EL devices have been actively conducted. The charge-emitting device having this laminated structure has a structure in which a charge transporting organic low-molecular compound (charge transporting material), a fluorescent organic low-molecular compound (light-emitting material) and an electrode are laminated, and a hole injected from the electrode is formed. Light is emitted when electrons move in the charge transporting material and recombine in the light emitting material. N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-
Biphenyl-4,4'-diamine (TPD) and 1,1-
Diamino compounds such as bis [4-bis (4-methylphenyl) aminophenyl] cyclohexane,
(N, N-diphenyl) aminobenzaldehyde-N,
A hydrazone compound such as N-diphenylhydrazone or 2- (4-biphenylyl) -5- (4-tert
An oxadiazole compound such as (-butylphenyl) -1,3,4-oxadiazole (PBO) and the like, and a fluorescent material such as an 8-quinolinol aluminum complex and a coumarin compound are used as a light emitting material.

[0005] However, a layer formed of an organic substance of an element is very thin, several tens to several hundreds of nanometers, and the voltage applied per unit thickness is very high, and is several mA / cm.
^Since it is driven at a high current density of ² , it generates a large amount of Joule heat. In addition, it is considered that deterioration with the passage of time due to long-term use and oxygen and moisture in the air are caused.

Therefore, the materials used are required to have electrical, thermal or chemical stability. However, it has been pointed out that the conventionally used charge transporting material lacks the above-mentioned stability, and is cited as one of the problems in stability and storage stability of the organic EL device during light emission. For example, in the case of an electron transport material,
As described in JP-A-109454, etc., 2-
(4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (PBO)
However, although the use of oxadiazole derivatives as electron transport materials has been proposed, the resulting thin films are easily crystallized and are not satisfactory in terms of charge transport / injection characteristics. In addition, there are few types of electron transport materials other than oxadiazole compounds, and it is presently desirable to develop further materials having excellent charge transport / injection characteristics in terms of low voltage driving and high efficiency. .

[0007] Further, it is reported that a coating method is preferable in terms of manufacturing method from the viewpoint of simplification of manufacturing, processability, enlargement of area, cost, and the like, and that an element can be obtained by a casting method (50th report). Proceedings of the Japan Society of Applied Physics, 29p-ZP-5 (1989), Proceedings of the 51st Applied Physics Society of Japan, 28a-PB-7 (199)
0)). However, the charge transport material has poor solubility and compatibility with solvents and resins, and thus is easily crystallized, and the coating method has a defect in production or characteristics.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide high luminance and stable performance even when used repeatedly. An object of the present invention is to provide an organic EL device that can be easily manufactured.

[0009]

As a result of intensive studies on the charge transporting material to achieve the above object, the compound represented by the following general formula (I) has been found to exhibit electron injection characteristics, electron mobility, They have found that they have the ability to form thin films, and have completed the present invention.

That is, an organic EL device according to the present invention is an electroluminescent device comprising one or a plurality of organic compound layers sandwiched between a pair of electrodes, at least one of which is transparent or translucent. At least one of the layers contains at least one compound represented by the following general formula (I).

[0011]

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[In the general formula (I), X represents a group selected from the following structural group 1, and is composed of a cyclic atom group composed of A and two carbon atoms and a cyclic atom group composed of B and two carbon atoms. The cyclic atom group independently represents a structure selected from the following structural group 2. ]

[0013]

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[In the structural groups 1 and 2, Y represents S, Se or Te, and R ₁ , R ₂ and R ₅ each independently represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aryl group. Represents an unsubstituted aralkyl group, R ₃ ,
R ₄ , R ₆ , R ₇ and R ₈ each independently represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, an alkoxy group, a halogen atom, a nitro group, a cyano group or Carboxylic acid ester group C
O ₂ R ₁ (where R ₁ is as defined above). ]

In the organic EL device of the present invention, the organic compound layer is of a function-separated type, for example, composed of at least a light emitting layer and an electron transport layer, composed of at least a hole transport layer, a light emitting layer and an electron transport layer, or A layer comprising at least a hole transporting layer and a light emitting layer, wherein the light emitting layer or the electron transporting layer contains the compound represented by the general formula (I), or has both carrier transporting ability and light emitting ability, that is, organic The compound layer may be composed of at least a light-emitting layer, and the light-emitting layer may contain any of the compounds represented by the general formula (I). The light emitting layer in the function separation type may have both carrier transporting ability and light emitting ability, or may have only light emitting ability.

In the organic EL device of the present invention, the light-emitting layer may contain a charge-transporting material (a hole-transporting material, an electron-transporting material other than the compound represented by the formula (I)), This charge transporting material (hole transporting material)
Is preferably a hole transporting polymer.
Further, it is preferable that the hole transporting layer contains a hole transporting polymer.

[0017]

DETAILED DESCRIPTION OF THE INVENTION An organic EL device according to the present invention comprises one or more organic compound layers sandwiched between a pair of electrodes, at least one of which is transparent or translucent. At least one of the organic compound layers contains at least one compound represented by the following general formula (I). Since the compound represented by the general formula (I) exhibits excellent electron injection properties, electron mobility, and thin film forming ability,
The organic EL device of the present invention having a layer containing the same has high luminance, exhibits stable performance even when used repeatedly, and is an easy-to-manufacture device.

[0018]

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In the general formula (I), X represents a group selected from the following structural group 1, and represents a cyclic atom group composed of A and two carbon atoms and a cyclic atom group composed of B and two carbon atoms. The atom group independently represents a structure selected from the following structural group 2.

[0020]

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In the structural groups 1 and 2, Y is S, Se or T
It represents e, R _1, R ₂ and R ₅ independently represents hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted aralkyl group,, R _3,
R ₄ , R ₆ , R ₇ and R ₈ each independently represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, an alkoxy group, a halogen atom, a nitro group, a cyano group or Carboxylic acid ester group C
O ₂ R ₁ (where R ₁ is as defined above).

Here, the alkyl group has 1 to 1 carbon atoms.
10 are preferred, for example, a methyl group, an ethyl group,
Examples include a propyl group and an isopropyl group. The alkoxyl group preferably has 1 to 10 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group. The aryl group preferably has 6 to 20 carbon atoms, and examples thereof include a phenyl group and a toluyl group. The aralkyl group preferably has 7 to 20 carbon atoms, and examples thereof include a benzyl group and a phenethyl group. Examples of the substituent of the substituted amino group include an alkyl group, an aryl group, and an aralkyl group, and specific examples are as described above. Examples of the substituent of the substituted aryl group and the substituted aralkyl group include a hydrogen atom, an alkyl group, an alkoxy group, a substituted amino group, and a halogen atom.

Hereinafter, specific examples of the compound represented by formula (I) will be shown, but the invention is not limited thereto.

[0024]

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[0025]

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The compounds of the general formula (I) can generally be synthesized from the corresponding quinone derivatives. For example, a tetracyanoquinodimethane derivative (X = C (C
In the case of N) ₂ ), titanium tetrachloride is added to a solution in which the corresponding quinone derivative is dissolved in a solvent such as chloroform, dioxane, or tetrahydrofuran, and the mixture is kept at a predetermined temperature. Next, a solution of malononitrile (CH ₂ (CN) ₂ ) in an amount equivalent to or more than the quinone derivative and, if desired, a third organic base are added to the suspension and reacted at a predetermined temperature, and the reaction is carried out by thin layer chromatography or the like. After confirming the progress, after completion of the reaction, the reaction solution is concentrated if desired, and then the product is crystallized by, for example, pouring into a non-solvent, and purified by recrystallization or the like. Similarly, compounds other than C (CN) ₂ can be obtained by substituting malononitrile with another active compound. For example, by using malonic acid diester (CH ₂ CO ₂ R ₁ R ₂ ), the following compound can be obtained, and N, N′-
By using bis (trimethylsilyl) -carbodiimide, a compound where X = NCN is obtained.

Next, the layer structure of the organic EL device of the present invention will be described in detail. The organic EL device of the present invention comprises a pair of electrodes, at least one of which is transparent or translucent, and one or more organic compound layers sandwiched between the electrodes, and at least one of the organic compound layers Comprises the compound represented by the general formula (I).

In the organic EL device of the present invention, when there is one organic compound layer, the organic compound layer means a light emitting layer having a carrier transporting ability, and the light emitting layer is formed of a compound represented by the general formula (I). It contains. When there are a plurality of organic compound layers (function-separated type), at least one of them is a light emitting layer (this light emitting layer may or may not have a carrier transporting ability). The organic compound layer of the carrier transport layer, that is, a hole transport layer, an electron transport layer,
Alternatively, it means a layer composed of a hole transport layer and an electron transport layer, and at least one layer excluding the hole transport layer contains the compound represented by the general formula (I). Specifically, for example, it is composed of at least a light emitting layer and an electron transport layer, composed of at least a hole transport layer, a light emitting layer and an electron transport layer, or composed of at least a hole transport layer and a light emitting layer, and is composed of a light emitting layer or an electron transport layer. Is the above-mentioned general formula (I)
And a compound containing a compound represented by the formula: Further, for example, an organic compound layer composed of a light-emitting layer, and the light-emitting layer containing the compound represented by the general formula (I) may also be used.

In the organic EL device of the present invention, the light emitting layer may contain a charge transporting material (a hole transporting material, an electron transporting material other than the compound represented by the general formula (I)), This charge transporting material (hole transporting material)
Is preferably a hole transporting polymer.
Further, it is preferable that the hole transporting layer contains a hole transporting polymer. Details will be described later.

Hereinafter, the present invention will be described in more detail with reference to the drawings, but is not limited thereto. 1 to 4
FIG. 3 is a schematic cross-sectional view for explaining a layer configuration of the organic EL element of the present invention. FIGS. 1, 2 and 4 show examples in which a plurality of organic compound layers are provided. In the case of (1), an example in which there is one organic compound layer is shown. 1 to 4
In the description below, components having similar functions are denoted by the same reference numerals.

The organic EL device shown in FIG. 1 is obtained by sequentially laminating a transparent electrode 2, a light emitting layer 4, an electron transport layer and a back electrode 7 on a transparent insulator substrate 1. The organic EL device shown in FIG. 2 is obtained by sequentially laminating a transparent electrode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, and a back electrode 7 on a transparent insulator substrate 1. The organic EL device shown in FIG. 3 is formed by sequentially laminating a transparent electrode 2, a light emitting layer 6 having a carrier transporting ability, and a back electrode 7 on a transparent insulator substrate 1. Organic EL shown in FIG.
The device comprises a transparent insulator substrate 1, a transparent electrode 2, a hole transport layer 3, a light emitting layer 6 having carrier transport ability, and a back electrode 7.
Are sequentially laminated. Hereinafter, each will be described in detail.

The transparent insulator substrate 1 is preferably transparent to extract light emission, and glass, plastic film, or the like is used. Like the transparent insulator substrate, the transparent electrode 2 is preferably transparent to extract light emission and has a large work function for injecting holes. Indium tin oxide (ITO), tin oxide (NESA), oxide An oxide film such as indium and zinc oxide, and gold, platinum, and palladium deposited or sputtered are used.

In the present invention, the organic compound layer containing the compound represented by the general formula (I) is shown in FIGS.
In the case of the layer structure of the organic EL element shown in FIG.
And the organic EL shown in FIGS. 3 and 4
In the case of a layer structure of the device, it functions as a light emitting layer 6 having a carrier transporting ability.

In the case of the layer structure of the organic EL device shown in FIGS. 1 and 2, the electron transporting layer 5 may be formed of the compound represented by the general formula (I) alone, but the electric characteristics are further improved. In order to improve electron mobility, for example, to improve the electron mobility, an electron transporting material other than the compound represented by the general formula (I) is mixed and dispersed in a range of 1 to 50% by weight to form. Is also good. Examples of the electron transporting material include oxadiazole derivatives, nitro-substituted fluorenone derivatives, diphenoquinone derivatives, thiopyrandioxide derivatives, and fluorenylidenemethane derivatives. Further, in order to improve the film forming property, a mixture with another general-purpose resin or the like may be used. Specific resins include polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, cellulose resin, urethane resin, epoxy resin, polystyrene resin, polyvinyl acetate resin,
Conductive resins such as styrene butadiene copolymer, vinyl chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, poly-N-vinyl carbazole resin, polysilane resin, polythiophene, polypyrrole, etc. Can be used. When these resins are used in combination, it is preferable to mix the compound represented by the general formula (I) so as to be 60% by weight or more of the material constituting the electron transport layer 5. In addition, as the additives, known antioxidants, ultraviolet absorbers, plasticizers, and the like can be used.

In the case of the layer structure of the organic EL device shown in FIGS. 1 and 2, a compound exhibiting a high fluorescence quantum yield in a solid state is used for the light emitting layer 4 as a light emitting material. When the light emitting material is an organic low molecular weight, it is necessary that a good thin film can be formed by applying a vacuum evaporation method or a solution or a dispersion containing a low molecular weight and a binder resin and drying. Also,
In the case of a polymer, apply a solution or dispersion containing itself
The condition is that a good thin film can be formed by drying. Preferably, in the case of a low-molecular organic compound, a chelate-type organometallic complex, a polynuclear or condensed aromatic ring compound, a perylene derivative, a coumarin derivative, a styryl arylene derivative, a silole derivative, an oxazole derivative, an oxathiazole derivative, an oxadiazole derivative, and the like, For polymers,
Examples include a polyparaphenylene derivative, a polyparaphenylenevinylene derivative, a polythiophene derivative, and a polyacetylene derivative. As preferred specific examples, the following exemplified compounds (III-1) to (III-15) are used.
It is not limited to these. In the exemplified compounds (III-13) to (III-15), n and x each independently represent an integer of 1 or more.

[0036]

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[0037]

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The light-emitting layer 4 may be doped with a dye compound different from the light-emitting material as a guest material in the light-emitting material for the purpose of improving the durability or luminous efficiency of the organic EL element. When forming the light emitting layer by vacuum evaporation, doping by co-evaporation, when forming the light emitting layer by applying and drying a solution or dispersion,
The doping is performed by mixing in a solution or a dispersion.
The doping ratio of the dye compound in the light emitting layer 4 is about 0.001 to 40% by weight, preferably about 0.01 to 10% by weight. As the dye compound used for such doping, an organic compound having good compatibility with the light emitting material and not hindering formation of a good thin film of the light emitting layer is used, and preferably a DCM derivative, a quinacridone derivative, and a rubrene derivative And porphyrin compounds. As preferred specific examples, the following exemplified compounds (IV-1) to (IV-4) are used, but the invention is not limited thereto.

[0039]

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In the layer structure of the organic EL device shown in FIGS. 2 and 4, a compound having an electron donating property is used for the hole transporting layer 3 as a hole transporting material. When the hole transporting material is an organic low molecule, it is necessary that a good thin film can be formed by a vacuum evaporation method or by applying and drying a solution or a dispersion containing a low molecule and a binder resin.
In the case of a polymer, a good thin film can be formed by applying and drying a solution or dispersion containing the polymer itself. Preferably, in the case of an aromatic amine-based low molecule such as a tetraphenylenediamine derivative, a triphenylamine derivative, or a carbazole derivative, 1,1-bis {4- (di-p-
Aromatic diamine compounds in which tertiary aromatic amine units of (tolylamino) phenyl @ cyclohexane are linked (JP-A-59-194393), 4,4, -bis [(N
-1-naphthyl) -N-phenylamino] aromatic amine containing two or more tertiary amines represented by biphenyl and having two or more condensed aromatic rings substituted by nitrogen atoms
234681), an aromatic triamine having a starburst structure as a derivative of triphenylbenzene (US Pat. No. 4,923,774), N, N′-diphenyl-N, N′-bis (3-methylphenyl) )-(1,
Aromatic diamines such as 1′-biphenyl) -4,4′-diamine (U.S. Pat. No. 4,764,625), α, α,
α ', α'-tetramethyl-α, α'-bis (4-di-
p-tolylaminophenyl) -p-xylene
-269084), triphenylamine derivatives which are sterically asymmetric as a whole molecule (JP-A-4-12927).
No. 1), a compound in which a pyrenyl group is substituted with a plurality of aromatic diamino groups (JP-A-4-175395), and an aromatic diamine in which a tertiary aromatic amine unit is linked by an ethylene group (JP-A-4-264189). Gazette), aromatic diamines having a styryl structure (JP-A-4-290851), those obtained by linking aromatic tertiary amine units with thiophene groups (JP-A-4-304466), and starburst-type aromatic triamines (JP-A-4-304466). JP-A-4-308688
JP-A-4-364, a benzylphenyl compound (JP-A-4-364)
153), those in which a tertiary amine is linked by a fluorene group (Japanese Patent Laid-Open No. 5-25473), triamine compounds (Japanese Patent Laid-Open No. 5-239455), and bisdipyridylaminobiphenyl (Japanese Patent Laid-Open No. 5-320634). ,
N, N ', N "-triphenylamine derivatives (Japanese Unexamined Patent Publication No.
1972), an aromatic diamine having a phenoxazine structure (Japanese Patent Application Laid-Open No. 5-290728), a diaminophenylphenanthridine derivative (Japanese Patent Application No. 6-456).
No. 69) can be used. When the organic low-molecular compound other than the aromatic amine-based low-molecular compound is used, a hydrazone compound (Japanese Unexamined Patent Application Publication No.
No. 315991), silazane compounds (U.S. Pat. No. 4,950,950), silanamine derivatives (JP-A-6-49079), phosphamine derivatives (JP-A-6-25659), quinacridone compounds,
-Di-p-tolylaminostilbene, 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino)
Use of stilbene compounds such as [styryl] stilbene, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, polysilane derivatives, etc. can do. In addition, besides the above-mentioned organic low molecular weight compound, a hole transporting polymer can also be suitably used, and specifically,
For example, polyvinyl carbazole or polysilane (App
l. Phys. Lett. 59, 2760, 19
91, etc.), polyphosphazene (JP-A-5-310949) and polyamide (JP-A-5-15-1).
No. 0949), polyvinyltriphenylamine (Japanese Patent Application No. 5-205377), and a polymer having a triphenylamine skeleton (Japanese Patent Application Laid-Open No. 4-1330065).
Polymers in which triphenylamine units are linked by a methylene group or the like (Synthetic Metals, vol. 55-57,
4163, 1993), polyesters containing aromatic amines (JP-A-8-21640), and polyethers containing aromatic amines (JP-A-8-17629).
No. 3) and a polymethacrylate containing an aromatic amine (J. Polym. Sci., Polym. Che.
m. Ed. , 21, 969, 1983). These compounds may be used alone, or may be used as a mixture as necessary. As a preferred specific example, the following exemplified compound (V-
1) to (V-7), but are not limited thereto.

[0041]

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[0042]

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In the case of the layer structure of the organic EL device shown in FIGS. 3 and 4, the light-emitting layer 6 having a carrier transporting property is, for example, at least a compound (electron transporting material) represented by the general formula (I). Is an organic compound layer in which a luminescent material is dispersed in an amount of 50% by weight or less. As the luminescent material, the exemplified compounds (III-1) to (III-12) are preferably used. In order to adjust the balance between holes and electrons, the general formula (I)
A specific charge transporting material other than the compound represented by (for example, the above-described hole transporting polymer or the like) may be used in combination. However, when a hole transporting material is used in combination, it is desirable to use an electron donating organic compound that does not show strong electron interaction with the compound represented by the general formula (I).
Further, a dye compound different from the light emitting material may be doped. Further, as in the case of the layer configuration of the organic EL element shown in FIG. 1, for the purpose of improving the film forming property, it may be mixed with another general-purpose resin or the like.

For the back electrode 7, a metal which can be vacuum-deposited and has a small work function for performing electron injection is used, and magnesium, aluminum, silver, indium and alloys thereof are particularly preferable. Further, a protective layer may be provided on the back electrode in order to prevent the element from being deteriorated by moisture or oxygen. Specific materials for the protective layer include In, Sn, P
b, metal such as Au, Cu, Ag, Al, MgO, SiO
2, metal oxides such as TiO ₂ , and resins such as polyethylene resin, polyurea resin, and polyimide resin. For forming the protective layer, a vacuum deposition method, a sputtering method, a plasma polymerization method, a CVD method, and a coating method can be applied.

In the organic EL devices shown in FIGS. 1 to 4, a hole transport layer 3 or a light emitting layer 4 is first formed on the transparent electrode 2 according to the layer constitution of each organic EL device. The hole transporting layer 3 and the light emitting layer 4 are respectively formed by dissolving or dispersing a hole transporting material and a light emitting material in a vacuum evaporation method or an organic solvent, and using the obtained coating solution to form the transparent electrode 2.
It is formed by forming a film thereon using a spin coating method, a dipping method, or the like.

Next, the electron transporting layer 5 and the light emitting layer 6 having a carrier transporting ability are first formed of the compound represented by the general formula (I) alone, or an electron transporting material and a light emitting material thereof, and if necessary. It is formed by dissolving or dispersing an electron transporting material and a hole transporting material in an organic solvent, and forming a film on the transparent electrode using the obtained coating solution by using a spin coating method, a dip method or the like. . Thereby, an organic EL element can be easily manufactured.

The thickness of each of the hole transport layer 3, light emitting layer 4 and electron transport layer 5 to be formed is 0.1 μm or less, particularly 0.1 μm or less.
It is preferably in the range of 03 to 0.08 μm. The thickness of the light emitting layer 6 having a carrier transporting ability is 0.03.
About 0.2 μm is preferable. The dispersion state of the hole transporting material, the light emitting material, the electron transporting material and the compound represented by the general formula (I) may be a molecular dispersion state or a fine particle dispersion state. In the case of a film forming method using a coating solution, in order to obtain a molecular dispersion state, a dispersion solvent is a common solvent of a hole transporting material, a light emitting material, an electron transporting material and the compound represented by the general formula (I). It is necessary to use, a dispersion solvent is a hole transporting material, a light emitting material,
It is necessary to select in consideration of the dispersibility and solubility of the electron transporting material and the solubility of the compound represented by the general formula (I). In order to disperse in the form of fine particles, a ball mill, sand mill, paint shaker, attritor,
A ball mill, a homogenizer, an ultrasonic method or the like can be used.

Finally, a back electrode 7 is formed on the electron transporting layer 5 or the light emitting layer 6 having a carrier transporting ability by a vacuum evaporation method, thereby completing the device.

In the organic EL device of the present invention, a current density of 1 to 200 mA /
Light can be emitted by applying a DC voltage of ² cm ² .

[0050]

The present invention will be described below by way of examples. The compound represented by the general formula (I) used (electron transporting material)
Was obtained, for example, as follows.

(Synthesis Example 1) -Exemplified Compound (II-1)
Synthesis of [BTDA-TCNQ (benzothiadiazolo-tetracyanoquinodimethane)]

[0052]

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In the above formula, the quinone derivative (2) as a raw material is obtained from R.S. Neidlein et al. (Chem. Be
r. 115, 2898 (1982)) and 533.2 × 10 ⁻² Pa (4 × 10 ⁻² Torr).
r), which was sublimated at 250 ° C. (melting point> 39)
0 ° C (decomposition)).

First, 26.0 g (26.5 mmo) of a quinone derivative (2) as a pink powder material ground in a mortar.
l) is suspended in 390 ml of dry chloroform (dry distilled over CaH ₂ ) in a 1 liter three-necked round bottom flask. Add 12 ml (4 equivalents) of TiCl ₄ and stir vigorously with a mechanical stirrer. Cool to −50 ° C. in a dry ice-methanol bath and obtain 55.13 g of malononitrile (boiling point: 103 to 106 ° C./14 mmHg) (7.
7.7 mmol, 2.9 eq) and dry pyridine (CaH
_A solution of 42 ml (20 equivalents) of 195 ml of dry chloroform was added dropwise while maintaining the temperature at -50 ° C. At this time, the color of the solution changes from orange to purple to yellow. The flask temperature is kept below -10 ° C in an ice-salt bath and the mixture is stirred vigorously for 6.5 hours. Next, 150 ml of cooled ether is added, whereby green-yellow crystals precipitate. (At this time, if the temperature is high, the decomposition products (green ones) increase, and the product becomes tar-like. The same applies when the number of equivalents is large. Therefore, the reaction needs to be performed promptly).

At this time, the unreacted quinone derivative (2) remains as an orange cubic crystal at the bottom of the flask, which can be easily separated from one crystal by decantation (also during recrystallization described later). The same is true.) The solid obtained by separating the green-yellow crystals with a Buchner funnel is T
Because it contains i-salt, ether (100 ml x 2 times)
After washing with water, plenty of water (100 ml x 2), hot water (~
(50 ° C., 200 ml × 2 times) and dried under reduced pressure.
7.16 g of crude product (yield 84%, melting point 350-3)
65 ° C (decomposition)). The crude product was fractionally recrystallized with acetone, sublimated (4 × 10 ⁻² Torr, 300 ° C.) to obtain a yellow powder, and finally recrystallized from acetonitrile to obtain yellow needles (Exemplified Compound (II-1)) ) Got. 6.72 g final yield (72% final yield, mp 375-380 ° C)
(Decomposition)).

The obtained yellow needles (exemplified compound (II-
Elemental analysis was performed for 1)), and the following measured values were obtained. Elemental analysis: Calculated _{C 12 N 8 S 2 (%} ): C45.00; N34.98; S20.
02 actual value (%): C45.19; N35.16; S20.
14 Mass: m / e (%) 320 (M +, 100)

Synthesis Example 2 Synthesis of Exemplified Compound (II-2) [TDA-TCNNQ (thiadiazolo-tetracyanonaphthoquinodimethane)]

[0058]

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The raw material quinone derivative (4) in the above formula
(Thiadiazolonaphthoquinone) is R.A. Naefe et al. (Chem. Ber., 90, 1137 (1957)).
And purified by silica gel (G-22) chromatography (eluent: CH ₂ Cl ₂ ) (melting point: 245 to 248 ° C. (decomposition)).

First, the raw material quinone derivative (4) 1.10
g (5.09 mmol) in a 200 ml three-neck round bottom flask
Suspend in 50 ml of dry chloroform in the flask. Ti
Cl _FourAdd 2.2 ml (4 equivalents) and cool to 0 ° C in an ice-water bath
Reject. 6.70 g of malononitrile while maintaining at 0 ° C
(102 mmol, 20 equivalents) and 16 ml of dry pyridine
(70 equivalents) of 50 ml of dry chloroform solution is added dropwise.
You. After stirring at room temperature for 20 minutes, pour into 100 ml of water,
Separate the salt and use methylene chloride (20ml x 5 times)
Wash. Separate quickly and separate the aqueous layer with methylene chloride (50
ml × 2), and the combined organic layers were washed with water (150 ml).
ml × 6 times) and then Na_TwoSO_FourAnd dry. low temperature(~
(20 ° C.) and concentrate the solvent (〜20 ml),
The yellow precipitate which separates out by adding ml is filtered off. Crude product
1.01 g (64%, melting point 268-271 ° C (decomposition))
Get. This was recrystallized from methylene chloride-hexane
Yellow needles having a melting point of 277-278 ° C (decomposition)
(II-2)) was obtained. Final yield was 55%.

The obtained yellow needles (exemplified compound (II-
Elementary analysis was performed for 2)), and the following measured values were obtained. Elemental analysis: Calculated _{C 16 H 4 N 6 S (} %): C61.53; H1.29; N26.9
0; S10.27 Found (%): C61.16; H1.07; N26.2
2: S10.06 Mass: m / e (%) 312 (M +, 100)

(Synthesis Example 3) Illustrative Compound (II-3) [SeDA-TCNNQ (Selenadiazolo-tetracyanonaphthoquinodimethane)]
Synthesis of

[0063]

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First, 500 mg of the quinone derivative (6)
(1.90 mmol) is suspended in 30 ml of dry methylene chloride and 0.85 ml (4 equivalents) of TiCl _{4 is} added. A solution of 1.32 g (10 equivalents) of malononitrile and 6 ml (40 equivalents) of dry pyridine in 15 ml of dry methylene chloride was slowly added dropwise (up to 1.5 hours), and the mixture was stirred at room temperature for 8 hours while checking by thin layer chromatography. I do. After confirming that the spot of the raw material quinone derivative has disappeared, the mixture is poured into a mixture of 100 ml of water and 50 ml of methylene chloride for extraction. The aqueous layer further contains methylene chloride (50 m
1 × 2), and the combined organic layers were washed with water (100 ml).
× 3), and then dried over Na ₂ SO ₄ . After the solvent was distilled off, 30 ml of ether was added, and the crystals were separated and dried to obtain 452 mg (66%) of a crude product. Melting point 330-350
° C (decomposition). This was recrystallized from methylene chloride-hexane to obtain a yellow powder (exemplified compound (II-3)). Melting point: 335-370 ° C (decomposition).

The obtained yellow powder (exemplified compound (II-
Elementary analysis was performed for 3)), and the following measured values were obtained. Elemental analysis: Calculated _{C 16 H 4 N 6 Se (} %): C53.50; H1.12; N23.4
0 Found (%): C53.31; H1.00; N23.3.
0

(Synthesis Example 4) -Exemplified Compound (II-9) [TDA-DCNNQI (Thiadiazolo-dicyanonaphthoquinodiimine)]-

[0067]

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First, 100 mg (0.463) of the raw material quinone derivative (4) (thiadiazoloonaphthoquinone) was added to 1
Dissolve in 0 ml of dry methylene chloride and add TiCl ₄ 0.2
Add ml (4 equivalents). 830 mg (9.6 equivalents) of N, N'-bis (trimethylsilyl) carbodiimide
Add ml dry CH2Cl2 solution and reflux for 8 hours. 2
Pour into 0 ml of water, separate, and separate the aqueous layer with methylene chloride (2
0 ml), and the combined organic layers were washed with water (50 ml)
Then, it is dried over Na ₂ SO ₄ . The solvent is distilled off and 109
mg (89%) of crude product are obtained. This was recrystallized from methylene chloride-hexane to give a dark yellow powder (exemplified compound (I)
I-9)) was obtained. Melting point 275-280 ° C (decomposition).

The obtained yellow powder (exemplified compound (II-
Elemental analysis was performed on 9)), and the following measured values were obtained. Elemental analysis: C ₁₂ H ₄ N ₆ Calculated S (%): C54.54; H1.53 ; N31.8
0; S12.13 Actual value (%): C54.71; H1.37; N31.2
9; S11.50

Example 1 A 2 mm-wide strip-shaped etched ITO glass substrate was ultrasonically cleaned with 2-propanol (for use in the electronics industry, manufactured by Kanto Chemical Co.) and then dried. A 0.050 μm-thick hole transport layer composed of the hole transport material represented by the exemplified compound (V-2) is formed on the substrate by a light emitting material represented by the exemplified compound (III-1). A light emitting layer having a thickness of 0.065 μm was sequentially formed by a vacuum evaporation method. Subsequently, a thickness of 0.050 composed of the exemplified compound (II-1) obtained in Synthesis Example 1.
An electron transport layer having a thickness of μm is formed by a vacuum evaporation method.
A g-Ag alloy was deposited by co-evaporation to a width of 2 mm and 0.1 mm.
A back electrode having a thickness of 5 μm was formed so as to cross the ITO electrode. The effective area of the formed organic EL element is 0.04c.
m ² .

Example 2 A solution was prepared by dissolving the hole-transporting polymer represented by the exemplified compound (V-6) at a ratio of 5% by weight in dichloroethane, and 0.1 μm of polytetrafluoroethylene (PTFE) was prepared. ) An organic EL device was produced in the same manner as in Example 1 except that the solution obtained by filtration with a filter was applied by a spin coater method to form a hole transport layer having a thickness of 0.050 μm. This organic E
The effective area of the L element was 0.04 cm ² .

Example 3 A solution was prepared by dissolving the hole-transporting polymer represented by the above exemplified compound (V-7) at a ratio of 5% by weight in dichloroethane, and 0.1 μm of polytetrafluoroethylene (PTFE) was prepared. ) An organic EL device was produced in the same manner as in Example 1 except that a solution obtained by filtration with a filter was applied by a spin coater method to form a hole transport layer having a thickness of 0.050 μm. This organic E
The effective area of the L element was 0.04 cm ² .

Example 4 1 part by weight of Exemplified Compound (II-1) obtained in Synthesis Example 1 used in Example 1, 1 part by weight of Exemplified Compound (III-1) as a luminescent material, hole transport As a material, 2 parts by weight of the exemplified compound (V-5) was mixed to prepare a 10% by weight dichloroethane dispersion,
The solution was filtered through a 0.1 μm PTFE filter. Using this solution, a 0.15 μm-thick luminescent layer having a carrier transporting ability was formed on a glass substrate on which a strip-shaped ITO electrode having a width of 2 mm was formed by etching by a spin coater method. After being sufficiently dried, a Mg-Ag alloy was deposited by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to cross the ITO electrode. The effective area of the formed organic EL device was 0.04 cm ² .

Example 5 2 parts by weight of Exemplified Compound (II-1) obtained in Synthesis Example 1 used in Example 1 and 1 part by weight of Exemplified Compound (III-1) as a luminescent material were mixed. A 10 wt% m-cresol dispersion was prepared by dispersing in a sand mill using 1 mmφ glass beads for 2 hours, and filtered with a 0.1 μm PTFE filter. Next, a 0.050 μm thick layer made of the hole transporting material represented by the above-mentioned exemplary compound (V-2) was formed on a glass substrate on which a 2 mm-wide strip-shaped ITO electrode was formed by etching.
m hole transport layer is formed by a vacuum deposition method,
The above 10% by weight m-cresol dispersion was applied by a spin coater method to form a 0.15 μm-thick light-emitting layer having a carrier transporting ability. After drying sufficiently, Mg-Ag
Alloy deposited by co-evaporation, 2mm width, 0.15μm
An organic EL device was manufactured by forming a thick back electrode so as to cross the ITO electrode. The effective area of this organic EL device was 0.04 cm ² .

Example 6 An organic EL device was prepared in the same manner as in Example 1 except that the exemplified compound (II-2) obtained in Synthesis Example 2 was used instead of the exemplified compound (II-1). Produced.

Example 7 An organic EL device was prepared in the same manner as in Example 4 except that the exemplified compound (II-2) obtained in Synthesis Example 2 was used instead of the exemplified compound (II-1). Produced.

Example 8 An organic EL device was prepared in the same manner as in Example 1 except that the exemplified compound (II-3) obtained in Synthesis Example 3 was used instead of the exemplified compound (II-1). Produced.

Example 9 An organic EL device was prepared in the same manner as in Example 4, except that the exemplified compound (II-3) obtained in Synthesis Example 3 was used instead of the exemplified compound (II-1). Produced.

(Example 10) In place of the exemplified compound (II-1), the exemplified compound (II-9) obtained in Synthesis Example 4
An organic EL device was produced in the same manner as in Example 1 except that was used.

(Example 11) In place of the exemplified compound (II-1), the exemplified compound (II-9) obtained in Synthesis Example 4
An organic EL device was produced in the same manner as in Example 4 except that was used.

(Comparative Example 1) A 2 mm wide strip-shaped etched ITO glass substrate was subjected to ultrasonic cleaning with 2-propanol (for use in the electronics industry, manufactured by Kanto Kagaku) and then dried. On this substrate, a 0.050 μm-thick hole transporting layer composed of the hole transporting material represented by Exemplified Compound (V-2) was formed to a thickness of 0.15 μm composed of Exemplified Compound (III-1). Light emitting layers of 065 μm were sequentially formed by a vacuum evaporation method. Subsequently, a compound represented by the following structural formula (V
An electron transport layer having a thickness of 0.050 μm constituted by I) is formed by a vacuum evaporation method, and a Mg-Ag alloy is finally evaporated by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm as an ITO electrode. It was formed to cross. The effective area of the formed organic EL device was 0.04 cm ² .

[0082]

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Comparative Example 2 2 parts by weight of the exemplified compound (V-5) as a hole transporting material, 0.1 part by weight of the exemplified compound (III-1) as a light emitting material, and 1 part by weight of Exemplified Compound (VI) was mixed,
A 10% by weight dichloroethane solution was prepared and filtered with a 0.1 μm PTFE filter. Using this solution,
A 0.15 μm-thick luminescent layer was formed by applying a spin coater method on a glass substrate on which a rectangular ITO electrode having a width of mm was formed by etching. After thoroughly drying,
Mg-Ag alloy is deposited by co-evaporation, 2 mm width,
A back electrode having a thickness of 0.15 μm was formed so as to cross the ITO electrode. The effective area of the formed organic EL element is 0.1.
04 cm ² .

Comparative Example 3 An organic EL device was manufactured in the same manner as in Comparative Example 1 except that the formation of the electron transport layer was omitted.

Comparative Example 4 An organic EL device was manufactured in the same manner as in Comparative Example 2, except that the mixing of the electron transporting material was omitted in forming the light emitting layer.

(Evaluation) Examples 1 to 5 produced as described above
11. The organic EL devices of Comparative Examples 1 to 4 were placed in a vacuum (13
A DC voltage was applied at 3.3 × 10 ⁻³ Pa (10 ⁻³ Torr) with the ITO electrode side plus and the Mg-Ag back electrode minus, and the emission was measured to determine the maximum brightness and emission at this time. The color was evaluated. Table 8 shows the results. In addition, the emission lifetime of the organic EL element was measured in dry nitrogen. The evaluation of the light emission life was such that the initial luminance was 50 cd /
The current value is set so as to be m ^2, and the time until the luminance is reduced by half from the initial value by constant current driving is determined as the element life (hou).
r). The driving current density at this time is shown in Table 1 together with the element life.

[0087]

[Table 1]

From the examples and comparative examples, it can be seen that the organic EL device using the compound represented by the above general formula (I) is capable of high luminance, high efficiency and excellent in durability. In addition, since there are few defects such as pinholes by using a spin coating method, a dip method or the like, and it is possible to easily form a large thin film and form a good thin film, the organic thin film of the present invention formed using the thin film can be formed easily. It can be seen that the EL element is advantageous in terms of manufacturing cost.

[0089]

As described above, according to the present invention, it is possible to provide an organic EL device which has high luminance, exhibits stable performance even when used repeatedly, and is easy to manufacture.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of a layer configuration of an organic electroluminescent device of the present invention.

FIG. 2 is a schematic configuration diagram showing another example of the layer configuration of the organic electroluminescent element of the present invention.

FIG. 3 is a schematic configuration diagram showing another example of the layer configuration of the organic electroluminescent element of the present invention.

FIG. 4 is a schematic configuration diagram showing another example of the layer configuration of the organic electroluminescent element of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transparent insulator substrate 2 transparent electrode 3 hole transport layer 4 light emitting layer 5 electron transport layer 6 light emitting layer having carrier transporting ability 7 back electrode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/14 H05B 33/14 B (72) Inventor Hiroto Yoneyama 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Inside (72) Inventor Eiichi Hirose 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Takeshi Agata 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor 1600, Takematsu, Minamiashigara, Kanagawa Prefecture Fuji Xerox Co., Ltd. (72) Inventor Katsuhiro Sato 1600, Takematsu, Minamiashigara, Kanagawa Prefecture Fuji Xerox, Inc. EB00

Claims (8)

[Claims] 1. An electroluminescent device comprising one or more organic compound layers sandwiched between a pair of electrodes, at least one of which is transparent or translucent, wherein at least one of the organic compound layers has the following general formula: An organic electroluminescent device comprising at least one compound represented by the formula (I). Embedded image [In the general formula (I), X represents a group selected from the following structural group 1, and includes a cyclic atom group composed of A and two carbon atoms and a cyclic atom group composed of B and two carbon atoms. Represents a structure independently selected from the following structural group 2. ] [In the structural groups 1 and 2, Y represents S, Se or Te;
R ₁ , R ₂ and R ₅ each independently represent a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and R ₃ , R ₄ , R ₆ , R ₇
And R ₈ are each independently a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aralkyl group, an alkoxy group, a halogen atom, a nitro group, a cyano group or a carboxylate group CO ₂ R ₁ (Wherein R ₁ is as defined above). ] 2. The method according to claim 1, wherein the organic compound layer comprises at least a light emitting layer and an electron transporting layer, and the electron transporting layer contains at least one compound represented by the following general formula (I). The organic electroluminescent device according to claim 1, wherein 3. The organic compound layer comprises at least a hole transport layer, a light emitting layer and an electron transport layer, and the electron transport layer contains at least one compound represented by the following general formula (I). The organic electroluminescent device according to claim 1, wherein 4. The organic compound layer comprises at least a light emitting layer, and the light emitting layer contains at least one compound represented by the following general formula (I). 3. The organic electroluminescent device according to claim 1. 5. The organic compound layer comprises at least a hole transport layer and a light-emitting layer, and the light-emitting layer contains at least one compound represented by the following general formula (I). The organic electroluminescent device according to claim 1. 6. The organic electroluminescent device according to claim 4, wherein the light emitting layer contains a charge transporting material. 7. The organic electroluminescent device according to claim 6, wherein the charge transporting material is a hole transporting polymer. 8. The organic electroluminescent device according to claim 3, wherein the hole transporting layer contains a hole transporting polymer.