JPH0820770A - Hole-transporting material and its use - Google Patents

Abstract

PURPOSE:To obtain a durable hole-transporting material excellent in hole- transporting properties, an element made of this material, an electroluminescent element made of this material and having a high luminance, a high luminous efficiency and high reliability realized by less deterioration in luminescence, and an electrophotographic photoreceptor having good electrophotographic properties such as photoreceptivity, hole-transporting properties, initial surface potential and dark decay. CONSTITUTION:This material is represented by the formula [wherein R<1> to R<6> are each hydrogen, a halogen, an alkyl, alkoxyl, cycloalkyl, a carboxyclic aromatic group or a heterocyclic group; and R<7> and R<8> are each hydrogen, a halogen, an alkyl or alkoxyl].

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hole transport material having a phenanthrene structure, wherein the phenanthrene compound is
It can be used as a light-sensitive material or an organic photoconductive material, and more specifically, it can be used as a hole light-transporting material for an organic electroluminescence (EL) element or an electrophotographic photoreceptor used for a flat light source or display.

[0002]

2. Description of the Related Art Organic photoconductive materials which have been developed as photosensitive materials and hole transport materials have many advantages such as low cost, various processability and no pollution, and many compounds have been proposed. ing. For example, oxadiazole derivatives (U.S. Pat. No. 3,189,447), oxazole derivatives (U.S. Pat. No. 3,257,203), hydrazone derivatives (U.S. Pat. No. 3,717,462, JP-A-54- 5
9,143, US Pat. No. 4,150,978), triarylpyrazoline derivatives (US Pat. No. 3,820,
989, JP-A-51-93,224, JP-A-55-
108,667), arylamine derivatives (US Pat. No. 3,180,730, US Pat. No. 4,232,10).
3, JP-A-55-144,250, and JP-A-56-1.
19,132, JP-A-5-39248, stilbene derivatives (JP-A-58-190,953, JP-A-59-59).
195, 658) and other organic photoconductive materials are disclosed.

As one of the technologies utilizing the hole transport material, there is an organic EL element. E using organic substances
The L element is promising for use as a solid-state light emitting inexpensive large area full color display element, 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, this is a phenomenon in which 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.

The conventional organic EL element has a higher driving voltage and lower emission brightness and emission efficiency than the inorganic EL element.
In addition, the deterioration of the characteristics was remarkable and it was not put to practical use.
In recent years, an organic EL in which thin films containing an organic compound having a high fluorescence quantum efficiency that emits light at a low voltage of 10 V or less are laminated
The device has been reported and is of great interest (see Applied Physics Letters, 51, 913, 1987). In this method, the metal chelate complex is added to the phosphor layer,
High-luminance green light emission is obtained by using an amine compound in the hole injection layer, and the luminance is several hundreds 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.

However, although the organic EL devices to date have been improved in the emission intensity due to the improved structure, they still do not have sufficient emission brightness. Further, it has a big problem that it is inferior in stability when repeatedly used. Therefore, in order to develop an organic EL device having higher emission brightness and excellent stability in repeated use, it is desired to develop a hole transport material having excellent hole transport ability and durability. It is rare.

Further, as a technique utilizing the hole transport material, there is an electrophotographic photoreceptor. The electrophotographic method is
It is one of the image forming methods invented by Carlson.
In this method, after the photoconductor is charged by corona discharge, it is exposed to a light image to obtain an electrostatic latent image on the photoconductor, toner is attached to the electrostatic latent image for development, and the obtained toner image is printed on a paper. Consists of transferring to. The basic characteristics required for a photoconductor in such an electrophotographic system are that an appropriate potential is maintained in a dark place, that there is little discharge of electric charge in a dark place, and that light is rapidly discharged by light irradiation. There are things to do. Conventional electrophotographic photoreceptors have used inorganic photoconductors such as selenium, selenium alloys, zinc oxide, cadmium sulfide and tellurium. These inorganic photoconductors have advantages such as high durability and a large number of printable sheets, but problems such as high manufacturing cost, poor processability, and toxicity have been pointed out. . Although organic photoconductors have been developed to overcome these drawbacks, electrophotographic photoconductors using a conventional organic photoconductive material as a hole transport material have not been improved in charging property, sensitivity and residual potential. At present, the electrophotographic properties are not always satisfactory, and they have excellent charge transporting ability,
It has been desired to develop a durable hole transport material.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hole transporting material having excellent hole transporting ability and having durability, and moreover, repeating using the hole transporting material. It is an object of the present invention to provide an organic EL element and an electrophotographic photosensitive member which are excellent in stability during use.

[0008]

As a result of intensive investigations by the present inventors, at least one hole transporting material represented by the general formula [1] has a large hole transporting ability, and the hole transporting material has a large hole transporting ability. The inventors have found that the stability is also excellent and have reached the present invention. That is, the present invention is a hole transport material represented by the following general formula [1]. General formula [1]

Embedded image [Wherein, R ^{1 to} R ⁶ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted Carbocyclic aromatic group,
It represents a substituted or unsubstituted heterocyclic group, and R ^{7 to} R ⁸ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. ]

Further, the present invention is the hole transport material according to claim 2, wherein the general formula [1] is the general formula [2]. General formula [2]

[Chemical 4] [In the formula, R ^{1 to} R ¹⁰ have the same meanings as described above. Furthermore, the present invention provides an organic electroluminescent device comprising a light emitting layer or a plurality of organic compound thin films including a light emitting layer between a pair of electrodes, wherein at least one layer contains the hole transport material. It is a luminescence element.

Further, the present invention is an electrophotographic photosensitive member comprising a charge generating material and a hole transporting material on a conductive substrate, wherein the hole transporting material is used. Is.

Specific examples of R _{1 to} R ⁶ of the general formula [1] in the present invention are hydrogen atom, chlorine, bromine, iodine,
Substitution of halogen atom such as 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 Or an unsubstituted alkyl group, methoxy group, n-butoxy group,
tert-butoxy group, trichloromethoxy group, trifluoroethoxy group, pentafluoropropoxy group, 2,
2,3,3-tetrafluoropropoxy group, 1,1,
1,3,3,3-hexafluoro-2-propoxy group,
Substituted or unsubstituted alkoxy group such as 6- (perfluoroethyl) hexyloxy group, substituted or unsubstituted cycloalkyl group such as cyclopentane group, cyclohexyl group, phenyl group, tolyl group, chlorophenyl group, naphthyl group, biphenyl Group, diethylaminobiphenyl group,
Substituted or unsubstituted carbocyclic aromatic groups such as diphenylaminobiphenyl group, ditolylaminobiphenyl group, terphenyl group, quaterphenyl group, pyridine group, pyrazine group, pyrimidine group, triazine group, quinoxaline group, pyrrolidine group , A dioxane group, a piperidine group, a morpholine group and the like, which are substituted or unsubstituted heterocyclic groups.

Specific examples of R ^{7 to} R ⁸ include chlorine, bromine,
Iodine, halogen atom of fluorine, methyl group, ethyl group,
Propyl group, butyl group, sec-butyl group, tert-
Substituted or unsubstituted alkyl group such as butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, trichloromethyl group, methoxy group, n-butoxy group, tert-butoxy group, trichloromethoxy group, trifluoro group Ethoxy group, pentafluoropropoxy group,
2,2,3,3-tetrafluoropropoxy group, 1,
There are substituted or unsubstituted alkoxy groups such as 1,1,3,3,3-hexafluoro-2-propoxy group and 6- (perfluoroethyl) hexyloxy group, etc., but are not limited to the specific examples of the above substituents. It is not something that will be done.

In the present invention, the compound represented by the general formula [1] can be produced, for example, by the following method.

A phenanthrene compound represented by the general formula [1] can be produced by reacting the following 10-phenanthraquinone or the following 9,10-diaminophenanthrene with a corresponding amino derivative.

[0015]

Embedded image

[0016]

[Chemical 6]

Representative examples of the compounds of the present invention are shown below in Table 1.
However, the present invention is not limited to the following representative examples.

[0018]

[Table 1]

[0019]

[0020]

[0021]

The hole transport material of the present invention may be used alone or in combination. Further, it may be used in a mixture with another hole or electron transporting compound. Since the compound of the present invention has an excellent hole transporting property, it can be used very effectively as a hole transporting material.

First, the case where the compound represented by the general formula [1] is used as a hole transport material of an organic EL device will be described. 1 to 3 show examples of schematic views of the organic EL device used in the present invention. In the figure, generally, the electrode A 2 is an anode, and the electrode B 6 is a cathode. Also,
There is also an organic EL device laminated in a layer structure of (electrode A / light emitting layer / electron injection layer / electrode B), and the compound of the general formula [1] is
It can be suitably used in any element configuration.
Since the compound of the general formula [1] has a large hole transporting ability, it can be used as a hole transporting material in any of the hole injecting layer 3, the light emitting layer 4, and the electron injecting layer 5.

In the light emitting layer 4 of FIG. 1, if necessary, in addition to the compound of the general formula [1] of the present invention, a light emitting substance, a light emission auxiliary material, a hole transporting material for carrying carriers, and an electron transporting material. Can also be used. In the structure of FIG. 2, the light emitting layer 4 and the hole injection layer 3 are separated. With this structure, the hole injection efficiency from the hole injection layer 3 to the light emitting layer 4 is improved, and the light emission brightness and the light emission efficiency can be increased. in this case,
For light emission efficiency, it is desirable that the light emitting material used in the light emitting layer itself has an electron transporting property or that the light emitting layer has an electron transporting property by adding an electron transporting material.

The structure of FIG. 3 has an electron injection layer 5 in addition to the hole injection layer 3 to improve the efficiency of recombination of holes and electrons in the light emitting layer 4. 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. Also in the elements of FIGS. 2 and 3, if necessary, a light emitting substance, a light emission auxiliary material, a hole transporting material for carrier transport, and an electron transporting material can be used in combination. Further, the hole injection layer, the light emitting layer, and the electron injection layer may each be formed by a layer structure of two or more layers.

As the conductive material used for the anode of the organic EL device, one having a work function larger than 4 eV is suitable, and carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, platinum. , Palladium and their alloys, ITO substrates, metal oxides such as tin oxide and indium oxide called NESA substrates, and organic conductive resins such as polythiophene and polypyrrole are used. As the conductive material used for the cathode, one having a work function smaller than 4 eV is suitable, and magnesium, calcium, tin, lead, titanium,
Yttrium, lithium, ruthenium, manganese and the like and alloys thereof are used, but not limited to these. The anode and the cathode may be formed in a layered structure of two or more layers if necessary.

In the organic EL device, at least one of the electrode A shown by 2 and the electrode B shown by 6 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 1 is also transparent. The transparent electrode is made of the above-mentioned conductive material and is set by a method such as vapor deposition or sputtering so as to ensure a predetermined translucency. The electrode that takes out the emitted light is
It is desirable that the light transmittance is 10% or more.

The substrate 1 is not limited as long as it has mechanical and thermal strength and is transparent, but examples thereof include a glass substrate, a polyethylene plate, a polyether sulfone plate, and a polypropylene plate. Examples include transparent resins.

For formation of each layer of the organic EL device according to the present invention, any of dry film forming methods such as vacuum deposition and sputtering, and wet film forming methods 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 thin, pinholes and the like will occur, and even if an electric field is applied, sufficient emission brightness cannot be obtained. Normal film thickness is 5nm to 10μ
The range of m is preferred, but the range of 10 nm to 0.2 μm is more preferred.

In the case of the wet film forming method, a thin film is formed by using a liquid in which the material forming each layer is dissolved or dispersed in an appropriate solvent such as chloroform, tetrahydrofuran, dioxane, etc., which solvent is used. May be. Further, in any of the organic layers, an appropriate resin or additive may be used in order to improve the film-forming property and prevent pinholes in the film. Examples of such resins include insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, urethane, polysulfone, polymethylmethacrylate, and polymethylacrylate, and poly-
Examples thereof include photoconductive resins such as N-vinylcarbazole and polysilane, and conductive resins such as polythiophene and polypyrrole.

This organic EL device comprises a light emitting layer, a hole injection layer,
In the electron injection layer, if necessary, in addition to the compound of the general formula [1], a known light emitting substance, light emission auxiliary material, hole transporting material, or electron transporting material can be used.

Known luminescent substances or auxiliary substances for luminescent substances 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,
Examples include, but are not limited to, pyran, thiopyran, polymethine, merocyanine, imidazole chelated oxinoid compounds, quinacridone, rubrene, and the like and their derivatives.

The hole transporting material that can be used in combination with the hole transporting material of the general formula [1] has the ability to transport holes and has an excellent hole injecting effect on the light emitting layer or the light emitting material. However, compounds that can prevent excitons generated in the light emitting layer from moving to the electron injection layer or the electron transport material and have excellent thin film forming ability can be given. Specifically, phthalocyanine compounds, naphthalocyanine compounds, porphyrin compounds, oxadiazoles, triazoles, imidazoles,
Imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine type triphenylamine, styrylamine type triphenylamine, diamine type triphenylamine, etc. Examples thereof include, but are not limited to, derivatives thereof, and polymeric materials such as polyvinylcarbazole, polysilane, and conductive polymers.

The electron-transporting material has the ability to transport electrons, has an excellent electron-injecting effect on the light-emitting layer or the light-emitting substance, and has a hole-injecting layer or hole-transporting layer for excitons generated in the light-emitting layer. Examples thereof include compounds that prevent transfer to the material and have excellent thin film forming ability. For example, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxadiazole, perylene tetracarboxylic acid, fluorenylidene methane, anthraquinodimethane,
Examples include, but are not limited to, anthrone and derivatives thereof. 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.

In the organic EL devices shown in FIGS. 1, 2 and 3, the compound of the general formula [1] of the present invention can be used in any layer, and in addition to the compound of the general formula [1], At least one of a light emitting substance, a light emission assisting 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 element obtained by the present invention against temperature, humidity, atmosphere, etc., a protective layer is provided on the surface of the element or silicon oil or the like is enclosed to protect the entire element. It is also possible. As described above, in the present invention, since the compound of the general formula [1] is used for the organic EL device, the luminous efficiency and the luminous brightness can be increased. Also,
This device is extremely stable against heat and current, and because it can obtain practically usable light emission brightness at a low driving voltage, it is possible to greatly reduce deterioration, which was a big problem until now. It was

The organic EL device of the present invention is used as a flat panel display such as a wall-mounted TV 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.

Next, the case where the compound represented by the general formula [1] of the present invention is used as an electrophotographic photoreceptor will be described. The compound represented by the general formula [1] of the present invention can be used in any layer of an electrophotographic photoreceptor, but it is preferably used as a hole transport material because it has high hole transport properties. The compound acts as a hole-transporting substance, can transport charges generated by absorbing light extremely efficiently, and can provide a photoreceptor having excellent high-speed response. Further, since the compound is excellent in ozone resistance and light stability, a photoreceptor having excellent durability can be obtained.

The electrophotographic photosensitive member is a single-layer type photosensitive member in which a charge generating material and, if necessary, a photosensitive layer in which a charge transporting material is dispersed in a binder resin are provided on a conductive substrate. An undercoat layer, a charge generation layer, and a hole transport layer in this order,
Alternatively, there is a laminated type photoreceptor in which a hole transport layer and a charge generation layer are laminated in this order on a conductive substrate or an undercoat layer. Here, the undercoat layer may not be used if not necessary. If necessary, the photoreceptor may be provided with an overcoat layer for the purpose of protecting the surface from active gas and preventing filming by toner.

As the charge generating material, bisazo, quinacridone, indigo, perylene, perinone, polycyclic quinone,
Squarylium salt, azurenium salt, phthalocyanine,
Organic compounds such as naphthalocyanine, or selenium,
Inorganic substances such as selenium-tellurium alloy, cadmium sulfide, zinc oxide, and amorphous silicon can be used.

Each layer of the photoreceptor can be formed by vapor deposition or dispersion coating method. Dispersion coating is performed using a spin coater, an applicator, a spray coater, a dip coater, a roller coater, a curtain coater, a bead coater, etc., and drying is from room temperature to 200 ° C., 1
It is performed under static or blown conditions in the range of 0 minutes to 6 hours.
The film thickness of the photosensitive layer after drying is 5 to 50 μm in the case of a single-layer type photoconductor, and 0.01 to 5 μm, preferably 0.1 to 1 μm in the case of a laminated type photoconductor. And the hole transport layer is preferably 5 to 50 microns, preferably 10 to 20 microns.

The resin used for forming the photosensitive layer of the single-layer type photoreceptor, the charge generation layer or the hole transport layer of the laminated type photoreceptor can be selected from a wide range of insulating resins. Also, poly-N
-Selectable from organic photoconductive polymers such as vinylcarbazole, polyvinylanthracene and polysilanes.
Preferably, polyvinyl butyral, polyarylate,
Insulating resins such as polycarbonate, polyester, phenoxy, acrylic, polyamide, urethane, epoxy, silicon, polystyrene, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, phenol and melamine resin can be mentioned. The resin used for forming the charge generation layer or the hole transport layer is preferably 100% by weight or less with respect to the charge generation material or the hole transport material, but is not limited thereto. You may use resin in combination of 2 or more types.
Further, if necessary, the resin may not be used. Also,
The charge generation layer can also be formed by a physical film forming method such as vapor deposition or sputtering. In the vapor deposition or sputtering method, it is desirable to form the film in a vacuum atmosphere of preferably 10 ⁻⁵ Toor or less. It is also possible to form a film in an inert gas such as nitrogen, argon, or helium.

The solvent used when forming each layer of the electrophotographic photosensitive member is preferably selected from those which do not affect the undercoat layer and other photosensitive layers. Specifically, aromatic hydrocarbons such as benzene and xylene, ketones such as acetone, methyl ethyl ketone and cyclohexanone, alcohols such as methanol and ethanol, esters such as ethyl acetate and methyl cellosolve, carbon tetrachloride, chloroform and dichloromethane. However, aliphatic halogenated hydrocarbons such as dichloroethane and trichloroethylene, aromatic halogenated hydrocarbons such as chlorobenzene and dichlorobenzene, and ethers such as tetrahydrofuran and dioxane are used, but not limited thereto.

The hole-transporting layer is formed by applying a hole-transporting material alone or a coating solution prepared by dissolving the hole-transporting material in a resin. The hole transport material used in the present photoreceptor may be used in combination with other hole transport materials in addition to the compound of the general formula [1]. The compound of the general formula [1] has good compatibility with a resin and is less likely to precipitate crystals, and is therefore advantageous for improving sensitivity and durability. In order to improve electrophotographic characteristics, image characteristics, etc., an undercoat layer can be provided between the substrate and the organic layer if necessary, and as the undercoat layer, polyamides, casein, polyvinyl alcohol, gelatin, polyvinyl butyral are used. Resins such as and metal oxides such as aluminum oxide are used. The material of the present invention is not only used as a hole transport material of an electrophotographic photoreceptor for a copying machine or a printer, but also a photoelectric conversion element, a solar cell,
It can also be suitably used in the field of image sensors and the like.

[0044]

The present invention will be described in more detail based on the following examples. Method for synthesizing compound (2) 9,10-diaminophenanthracene ( 5 parts), 4-bromo-biphenyl (23 parts), sodium hydroxide (7 parts) and cuprous chloride (0.05 parts) are added, and the mixture is heated with stirring at 220 ° C for 30 hours. Then, it was cooled, extracted with 200 parts of ethyl acetate, concentrated with an evaporator, and the deposited precipitate was recrystallized with methanol. Eight parts of gray powder were obtained. 5 parts of this powder was heated and stirred with 12 parts of p-iodotoluene, 20 parts of potassium carbonate, and 0.1 parts of copper powder at 200 ° C. for 30 hours to obtain a brown solid. This was extracted with chloroform and chromatographed on silica gel to give a yellow powder 3
Got a part. As a result of molecular weight analysis, it was confirmed to be compound (3). The results of elemental analysis of the product are shown below. Elemental analysis result Calculated value (%) as C ₅₂ H ₄₀ N ₂ : C: 90.13 H: 5.78
N: 4.05 Found (%): C: 90.28 H: 5.59
N: 4.13

First, an organic EL device using the hole transport material of the present invention will be described. Example 1 On a washed glass plate with an ITO electrode, the compound (1),
Tris (8-hydroxyquinoline) aluminum complex,
Polycarbonate resin (PC-A) was dissolved in tetrahydrofuran at a ratio of 3: 2: 5, and a light emitting layer having a film thickness of 100 nm was obtained by a spin coating method. On top of that, an alloy of magnesium and silver mixed at a ratio of 10: 1 has a film thickness of 150.
nm electrode was formed to obtain the organic EL device shown in FIG.
With this device, light emission of 180 cd / m ² was obtained at a DC voltage of 5V.

Examples 2 to 13 The compounds shown in Table 2 were dissolved in chloroform on a washed glass plate with an ITO electrode, and a hole injection layer having a thickness of 50 nm was obtained by spin coating. Then, a tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited to form a light-emitting layer having a thickness of 30 nm, and an alloy in which magnesium and silver are mixed at a ratio of 10: 1 has a thickness of 100 nm.
nm electrodes were formed to obtain the organic EL device shown in FIG.
The light emitting layer was vapor-deposited in a vacuum of 10 ⁻⁶ Torr at a substrate temperature of room temperature. The device obtained the emission luminance shown in Table 2 at a DC voltage of 5V.

Comparative Example 1 N, N'-diphenyl-N, N'-as a hole transport material
(3-methylphenyl) -1,1'-biphenyl-4
Organic EL devices were produced in the same manner as in Examples 2 to 13 except that 4'-diamine (Compound 13) was used. The device obtained the emission luminance shown in Table 2 at a DC voltage of 5V.

Comparative Example 2 N, N, N ', N'-tetra (4
Organic EL devices were prepared in the same manner as in Examples 2 to 13 except that -methylphenyl) -9,10-diaminophenanthrene (Compound 14) was used. The device obtained the emission luminance shown in Table 2 at a DC voltage of 5V.

[0049]

[Table 2]

Example 14 Compound (4) was dissolved in tetrahydrofuran on a washed glass plate with an ITO electrode, and a hole injection layer having a thickness of 50 nm was obtained by spin coating. Then, a tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited to form a light-emitting layer having a thickness of 30 nm, and an alloy in which magnesium and silver are mixed at a ratio of 10: 1 has a thickness of 100 nm.
nm electrodes were formed to obtain the organic EL device shown in FIG.
The light emitting layer was vapor-deposited in a vacuum of 10 ⁻⁶ Torr at a substrate temperature of room temperature. This device has a DC voltage of 5 V
Light emission of cd / m ² was obtained.

Example 15 Compound (1) was vacuum-deposited on a washed glass plate with an ITO electrode to obtain a hole injection layer having a film thickness of 20 nm. Further, N, N'-diphenyl-N, N '-(3-methylphenyl) -1,1'-biphenyl-4,4'-diamine is vacuum-deposited to obtain a hole transport layer having a thickness of 30 nm. It was Then, a tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited 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 mixture ratio of magnesium and silver of 10: 1. Thus, an organic EL device was obtained. The hole injecting layer and the light emitting layer were vapor-deposited in a vacuum of 10 ⁻⁶ Torr at a substrate temperature of room temperature. With this device, light emission of about 450 cd / m ² was obtained at a DC voltage of 5V.

Example 16 N, N'-diphenyl-N, N '-(3-methylphenyl) -1,1'-on a washed glass plate with an ITO electrode
Biphenyl-4,4'-diamine was vacuum-deposited to obtain a hole injection layer having a film thickness of 50 nm. Then, tris (8-hydroxyquinoline) aluminum complex and compound (11)
Is vacuum-deposited at a ratio of 3: 1 to form a light-emitting layer having a thickness of 50 nm, and an electrode having a thickness of 150 nm is formed on the light-emitting layer having a thickness of 50: 1. Two
The organic EL device shown in was obtained. The hole injecting layer and the light emitting layer were vapor-deposited in a vacuum of 10 ⁻⁶ Torr at a substrate temperature of room temperature. This element is about 360 cd / m at DC voltage 5V.
A luminescence of ² was obtained.

Example 17 Compound (11) was applied onto a washed glass plate with an ITO electrode.
Was dissolved in chloroform, and a hole injection layer having a film thickness of 50 nm was obtained by a spin coating method. Then, a 50-nm-thick light-emitting layer of tris (8-hydroxyquinoline) aluminum complex is formed by a vacuum evaporation method, and then [2- (4-tert-butylphenyl)] is formed by a vacuum evaporation method.
An electron injection layer having a film thickness of 20 nm of [5- (biphenyl) -1,3,4-oxadiazole] was obtained. On top of that, an alloy of magnesium and silver mixed at a ratio of 10: 1 has a film thickness of 150.
nm electrodes were formed to obtain the organic EL device shown in FIG.
The device emitted light of about 320 cd / m ² at a DC voltage of 5V.

As shown in Table 2, the organic EL elements of this example exhibited high-luminance light emission at a low voltage, whereas the organic EL elements of Comparative Examples 1 and 2 had approximately half the emission luminance. Also,
When all the organic EL devices were made to continuously emit light at 1 mA / cm ² , the organic EL devices of this example could observe stable light emission for 1000 hours or more, but the organic EL devices of Comparative Examples 1 and 2 were observed. Deteriorated to half the initial emission brightness in 100 hours. The organic EL device of the present invention achieves improvement in luminous efficiency, luminous brightness, and long life,
It does not limit the light emitting substance, the light emission auxiliary material, the hole transporting material, the electron transporting material, the sensitizer, the resin, the electrode material and the like and the element manufacturing method which are used together.

Example 18 4 g of ε-type copper phthalocyanine, 2 g of compound (4), 14 g of polyester resin (Vylon 200: manufactured by Toyo Ind. Co., Ltd.)
Was dispersed with 80 g of tetrahydrofuran in a ball mill for 5 hours. This dispersion was applied onto an aluminum substrate and dried to prepare a single-layer type electrophotographic photoreceptor having a film thickness of 15 μm shown in FIG.

Example 19 6 g of dibromoanthanthrone, 2 g of compound (11),
Polyester resin (Byron 200: Toyo Defense Co., Ltd.)
12 g was dispersed with 80 g of tetrahydrofuran in a ball mill for 5 hours. This dispersion was applied onto an aluminum substrate and dried to prepare a single-layer type electrophotographic photoreceptor having a film thickness of 15 μm shown in FIG.

Examples 20 to 31 2 g of τ-type metal-free phthalocyanine and 2 g of polyvinyl butyral resin (BH-3: manufactured by Sekisui Chemical Co., Ltd.) were dispersed with 96 g of tetrahydrofuran in a ball mill for 2 hours. This dispersion was applied onto an aluminum substrate and dried to form a charge generation layer having a film thickness of 0.3 μm. Next, 10 g of the compound shown in Table 3 and a polycarbonate resin (L-125
0; Teijin Kasei Co., Ltd.) 10 g dichloromethane 80 g
Dissolved in. This coating liquid was applied onto the charge generation layer and dried to form a charge transport layer having a film thickness of 20 μm, and the laminated electrophotographic photoreceptor shown in FIG. 5 was produced.

Comparative Example 3 As a hole transport material, N, N'-diphenyl-N, N'-
(3-methylphenyl) -1,1'-biphenyl-4
Laminated electrophotographic photoreceptors were produced in the same manner as in Examples 20 to 31 except that 4′-diamine (Compound 13) was used.

Comparative Example 4 N, N, N ', N'-tetra (4
-Methylphenyl) -9,10-diaminophenanthrene (Compound 14), except Examples 20-31.
A laminated electrophotographic photosensitive member was produced in the same manner as in.

Example 32 N, N'-bis (2-carbomethoxyphenyl) -3,
2,9,10-Perylenedicarboximide 2g, polyvinyl butyral resin (BH-3: Sekisui Chemical Co., Ltd.)
2g together with 96g of tetrahydrofuran in a ball mill
Time dispersed. This dispersion was applied onto an aluminum substrate and dried to form a charge generation layer having a film thickness of 0.3 μm. Next, 10 g of the compound (10) and 10 g of a polycarbonate resin (L-1250; manufactured by Teijin Chemicals Ltd.) were dissolved in 80 g of dichloromethane. This coating liquid was applied onto the charge generation layer and dried to form a charge transport layer having a film thickness of 20 μm, and the laminated electrophotographic photoreceptor shown in FIG. 5 was produced.

The electrophotographic characteristics of the electrophotographic photosensitive member were measured by the following methods. Electrostatic Copy Paper Testing Device (EPA-810
0; manufactured by Kawaguchi Denki Seisakusho Co., Ltd., static mode 2, corona charging: -5.2 (kV), 5 (lux)
Of the initial surface potential (V ₀ ) and V ₀ and the surface potential (V ₂ ) when left in the dark for 2 seconds (dark decay rate: DDR ₂ = V ₂ / V ₀ ) , Half-exposure sensitivity (E _1/2 ) from the time when the charge amount decreases to 1/2 of the initial value after light exposure
The surface potential (VR ₃ ) after 3 seconds of light exposure was examined. Table 3 shows the electrophotographic characteristics of the electrophotographic photosensitive members of Examples 18 to 32 and Comparative Examples 3 and 4.

[0062]

[Table 3]

As shown in Table 3, the electrophotographic photoconductors of this example showed high charging property and high sensitivity, but the electrophotographic photoconductors of Comparative Examples 3 and 4 showed high charging property and high sensitivity. Was inferior. When the electrophotographic characteristics were measured repeatedly 10,000 times or more, all the electrophotographic photosensitive members of this example showed stable surface potential and sensitivity.

[0064]

Industrial Applicability According to the present invention, a compound having an excellent hole transporting ability can be obtained. The compound provided by the present invention has higher luminous efficiency, higher brightness, and longer life than conventional organic EL devices and excellent initial electrophotographic properties such as sensitivity, hole transport properties, initial surface potential, and dark decay rate. It was possible to obtain an electrophotographic photosensitive member with little fatigue against repeated use. Since the hole transport material of the present invention has a high solubility in an organic solvent, it is possible to obtain a uniform thin film even when forming the hole transport layer. Further, also in the vapor deposition film, since it becomes difficult to aggregate the thin film after forming the thin film, it becomes possible to prevent the deterioration of the device. For the above reasons, stable hole transport characteristics were obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic structure of an organic EL element used in an example.

FIG. 2 is a sectional view showing a schematic structure of an organic EL device used in Examples and Comparative Examples.

FIG. 3 is a sectional view showing a schematic structure of an organic EL element used in an example.

FIG. 4 is a sectional view showing a schematic structure of an electrophotographic photosensitive member used in Examples.

FIG. 5 is a cross-sectional view showing a schematic structure of electrophotographic photosensitive members used in Examples and Comparative Examples.

[Explanation of symbols]

 1. Substrate 2. Electrode A 3. Hole injection layer 4. Light emitting layer 5. Electron injection layer 6. Electrode B 7. Al substrate 8. Photosensitive layer 9. Charge generation layer 10. Hole transport layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tan Ogawa 2-13-3 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd. (72) Inventor Toshio Enokada 2-3-3 Kyobashi, Chuo-ku, Tokyo No. Toyo Inki Manufacturing Co., Ltd.

Claims (4)

[Claims] 1. A hole transport material represented by the following general formula [1]. General formula [1] [Wherein, R ^{1 to} R ⁶ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted Carbocyclic aromatic group,
It represents a substituted or unsubstituted heterocyclic group, and R ^{7 to} R ⁸ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. ] 2. The hole transport material according to claim 2, wherein the general formula [1] is the following general formula [2]. General formula [2] [In the formula, R ^{1 to} R ¹⁰ have the same meanings as described above. ] 3. An organic electroluminescence device comprising a light emitting layer or a plurality of organic compound thin films including a light emitting layer between a pair of electrodes, at least one layer containing the hole transporting material according to claim 1. An organic electroluminescence device that does. 4. An electrophotographic photoreceptor comprising a charge generating material and a hole transporting material on a conductive substrate, wherein the hole transporting material is the hole transporting material according to claim 1 or 2. Characteristic electrophotographic photoreceptor.