JP3079903B2 - Hole transport material and its use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hole transporting material having a phenanthrene structure.
It can be used as a photosensitive material or an organic photoconductive material. More specifically, it can be used as a hole transporting material for an organic electroluminescence (EL) element used for a flat light source or display or an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Organic photoconductive materials that 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. 5
9,143, U.S. Pat. No. 4,150,978), triarylpyrazoline derivatives (U.S. Pat.
No. 989, JP-A-51-93,224 and JP-A-55-93.
No. 108,667), arylamine derivatives (US Pat. No. 3,180,730, US Pat. No. 4,232,10).
3, JP-A-55-144250, JP-A-56-1
19,132, JP-A-5-39248), stilbene derivatives (JP-A-58-190,953, JP-A-59-9553)
No. 195,658) are disclosed.

[0003] One of the techniques using a hole transport material is an organic EL device. E using organic substances
The L element is expected to be used as a solid-state light-emitting inexpensive large-area full-color display element, and many developments have been made. Generally, an EL element is composed of a light emitting layer and a pair of opposed electrodes sandwiching the layer. In light emission, when an electric field is applied between both electrodes, electrons are injected from the cathode side, holes are injected from the anode side , and the electrons recombine with holes in the light emitting layer, and the energy level is changed to the conduction band. This is a phenomenon in which energy is emitted as light when returning to the valence band from.

[0004] Conventional organic EL devices have a higher driving voltage and lower luminous luminance and luminous efficiency than inorganic EL devices.
In addition, the characteristic deterioration was remarkable, and it had not been put to practical use.
2. Description of the Related Art In recent years, an organic EL in which a thin film containing an organic compound having high fluorescence quantum efficiency that emits light at a low voltage of 10 V or less is laminated.
Devices have been reported and are of interest (see Applied Physics Letters, vol. 51, p. 913, 1987). In this method, the metal chelate complex is converted into a phosphor layer,
High brightness green light emission is obtained by using an amine compound for the hole injection layer, and the brightness is several hundreds at a DC voltage of 6 to 7V.
It achieves cd / m ² and maximum luminous efficiency of 1.5 lm / W, and has performance close to the practical range.

[0005] However, organic EL devices up to now have improved luminous intensity due to the improved structure, but do not yet have sufficient luminous brightness. In addition, there is a major problem that the stability upon repeated use is poor. Therefore, in order to develop an organic EL device having higher emission luminance and excellent stability in repeated use, it is desired to develop a hole transporting material having excellent hole transporting ability and durability. It is rare.

Further, as a technique using a hole transport material, there is an electrophotographic photosensitive member. The electrophotographic method is
This is one of the image forming methods invented by Carlson.
In this method, after a photoconductor is charged by corona discharge, an optical image is exposed to obtain an electrostatic latent image on the photoconductor, toner is attached to the electrostatic latent image and developed, and the obtained toner image is printed on paper. Transfer to The basic characteristics required of the photoreceptor in such an electrophotographic system are that an appropriate potential is maintained in a dark place, that the electric charge is less discharged in the dark place, and that the electric charge is quickly discharged by light irradiation. And so on. 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 printing presses, but problems such as high production cost, poor workability, and toxicity have been pointed out. . To overcome these drawbacks, organic photoconductors have been developed.However, conventional electrophotographic photoconductors using organic photoconductive materials as hole transport materials are not suitable for charging, sensitivity and residual potential. At present, electrophotographic properties are not always satisfactory, and have excellent charge transport ability,
The development of a durable hole transport material has been desired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a durable hole transporting material having excellent hole transporting ability. It is an object of the present invention to provide an organic EL device and an electrophotographic photosensitive member having excellent stability during use.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that at least one kind of hole transporting material represented by the general formula [1] has a large hole transporting ability and can be used when the element is repeatedly used. The inventors have also found that the stability is excellent, and have reached the present invention. That is, the present invention is a hole transporting material represented by the following general formula [1]. General formula [1]

Embedded image [Wherein, R ^{1 to} R ⁶ each independently represent 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,
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 provides the hole transport material according to claim 2, wherein the general formula [1] is the general formula [2]. General formula [2]

Embedded image [Wherein, R ^{1 to} R ⁸ represent the same meaning as described above. ]

Further, the present invention relates to an electrophotographic photosensitive member using a charge generation material and a hole transport material on a conductive substrate, wherein the above-described hole transport material is used. It is.

Specific examples of R _{1 to} R ⁶ in the general formula [1] in the present invention include a hydrogen atom, chlorine, bromine, iodine,
Substitution of fluorine or the like with a halogen atom, 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, etc. Or an unsubstituted alkyl group, a methoxy group, an 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 groups such as 6- (perfluoroethyl) hexyloxy group, substituted or unsubstituted cycloalkyl groups such as cyclopentane group and 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 And a substituted or unsubstituted heterocyclic group such as dioxane group, piperidine group and morpholine group.

Specific examples of R ^{7 to} R ⁸ include chlorine, bromine,
Iodine, fluorine halogen atom, methyl group, ethyl group,
Propyl group, butyl group, sec-butyl group, tert-
Substituted or unsubstituted alkyl groups 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 Ethoxy group, pentafluoropropoxy group,
2,2,3,3-tetrafluoropropoxy group, 1,
There is a substituted or unsubstituted alkoxy group such as a 1,1,3,3,3-hexafluoro-2-propoxy group and a 6- (perfluoroethyl) hexyloxy group, but is limited to specific examples of the above substituents. It is not something to be done.

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

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

[0015]

Embedded image

[0016]

Embedded image

Hereinafter, typical examples of the compounds of the present invention are shown 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 as a mixture. Further, it may be used in a mixture with another hole or electron transporting compound. Since the compound of the present invention has excellent hole transporting properties, 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. FIGS. 1 to 3 show examples of schematic diagrams of an organic EL device used in the present invention. In the figure, generally, electrode 2, 2 is an anode, and electrode B, 6 is a cathode. Also,
There is also an organic EL device laminated with a layer structure of (electrode A / light-emitting layer / electron injection layer / electrode B), and the compound of general formula [1]
Any device configuration can be suitably used.
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 injection layer 3, the light emitting layer 4, and the electron injection layer 5.

The light-emitting layer 4 of FIG. 1 may include, if necessary, a light-emitting substance, a light-emitting auxiliary material, a hole-transporting material for transporting carriers, and an electron-transporting material, in addition to the compound of the general formula [1] of the present invention. 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 luminance and the light emission efficiency can be increased. in this case,
For luminous efficiency, it is desirable that the luminescent substance used in the luminescent layer itself has an electron transporting property, or that the luminescent layer is made to have an electron transporting property by adding an electron transporting material to the luminescent layer.

The structure shown in 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. In this manner, by making the organic EL element have a multilayer structure, it is possible to prevent a decrease in luminance and life due to quenching. 2 and 3, the light-emitting substance, the light-emitting auxiliary material, the hole-transporting material for transporting carriers, and the electron-transporting material can be used in combination, if necessary. Further, each of the hole injection layer, the light emitting layer, and the electron injection layer may be formed in a layer structure of two or more layers.

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

In the organic EL device, at least one of the electrode A 2 and the electrode B 6 is desirably 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 set so as to secure a predetermined light transmittance by a method such as vapor deposition or sputtering using the above-described conductive substance. The electrode that extracts light emission
It is desirable that the light transmittance be 10% or more.

The substrate 1 is not limited as long as it has mechanical and thermal strengths and is transparent. Examples thereof include a glass substrate, a polyethylene plate, a polyethersulfone plate and a polypropylene plate. Transparent resin.

The layers of the organic EL device according to the present invention can be formed by any of dry film forming methods such as vacuum evaporation and sputtering and wet film forming methods such as spin coating and dipping. The thickness is not particularly limited, but each layer needs to be set to an appropriate thickness. If the film thickness is too large, a large applied voltage is required to obtain a constant light output, resulting in poor efficiency. If the film thickness is too small, pinholes and the like are generated, and sufficient light emission luminance cannot be obtained even when an electric field is applied. Normal thickness is 5nm to 10μ
The range of m is suitable, but the range of 10 nm to 0.2 μm is more preferable.

In the case of the wet film forming method, a thin film is formed by using a solution in which the material for forming each layer is dissolved or dispersed in a suitable solvent such as chloroform, tetrahydrofuran, dioxane or the like. May be. Further, in any of the organic layers, an appropriate resin or additive may be used for improving film forming properties, preventing pinholes in the film, and the like. Examples of such a resin include insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, urethane, polysulfone, polymethyl methacrylate, and polymethyl acrylate;
Examples thereof include photoconductive resins such as N-vinylcarbazole and polysilane, and conductive resins such as polythiophene and polypyrrole.

The present organic EL device has 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 transport material, and electron transport material can also be used.

Known light-emitting substances or auxiliary materials for light-emitting substances include anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene and 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 derivatives thereof.

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 injection effect on the light emitting layer or the light emitting substance. In addition, a compound that prevents excitons generated in the light emitting layer from moving to the electron injection layer or the electron transport material and has excellent thin film forming ability can be used. Specifically, phthalocyanine compounds, naphthalocyanine compounds, porphyrin compounds, oxadiazole, triazole, imidazole,
Imidazolone, imidazolethione, pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole, hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidine triphenylamine, styrylamine triphenylamine, diamine triphenylamine, etc. And derivatives thereof, and high molecular materials such as polyvinyl carbazole, polysilane, and conductive polymers, but are not limited thereto.

The electron transporting material has a capability of transporting electrons, has an excellent electron injecting effect on a light emitting layer or a light emitting substance, and has a hole injecting layer or a hole transporting function of excitons generated in the light emitting layer. Compounds that prevent transfer to a material and have excellent thin film forming ability are exemplified. For example, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxadiazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane,
Examples include, but are not limited to, anthrones and derivatives thereof. The sensitization can also be performed 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 for any layer. At least one of a light emitting substance, a light emission auxiliary material, a hole transport material, and an electron transport material may be contained in the same layer. In order to improve the stability of the organic EL device obtained according to the present invention with respect to temperature, humidity, atmosphere, etc., a protective layer is provided on the surface of the device, or silicon oil or the like is sealed to protect the entire device. It is also possible. As described above, in the present invention, since the compound of the general formula [1] was used for the organic EL device, the luminous efficiency and the luminous brightness could be increased. Also,
This element is extremely stable against heat and current, and furthermore, it can emit light that can be used practically at a low driving voltage, so that the degradation, which was a major problem up to now, can be greatly reduced. Was.

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

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

The electrophotographic photoreceptor is a single-layer type photoreceptor having a photosensitive layer formed by dispersing a charge generating material and, if necessary, a charge transport material in a binder resin on a conductive substrate. An undercoat layer, a charge generation layer, and a hole transport layer were laminated in this order,
Alternatively, there is a laminated photoconductor in which a hole transport layer and a charge generation layer are laminated on a conductive substrate or an undercoat layer in this order. Here, the undercoat layer may not be used if unnecessary. The photoreceptor may be provided with an overcoat layer, if necessary, for the purpose of protecting the surface from an active gas and preventing filming with a 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, amorphous silicon and the like can be mentioned.

Each layer of the photoreceptor can be formed by vapor deposition or dispersion coating. The 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, or the like, and drying is performed from room temperature to 200 ° C.
It is carried out in the range of 0 minutes to 6 hours under static or blowing conditions.
The thickness of the photosensitive layer after drying is 5 to 50 μm for a single-layer type photoreceptor, and 0.01 to 5 μm, preferably 0.1 to 1 μm for a multilayer type photoreceptor. Yes, the hole transport layer is suitably 5 to 50 microns, preferably 10 to 20 microns.

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

The solvent used for 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 But 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 are not limited thereto.

The hole transport layer is formed by applying only the hole transport material or a coating solution obtained by dissolving the hole transport material in a resin. The hole transporting material used in the present photoreceptor can be used in combination with another hole transporting material in addition to the compound represented by the general formula [1]. The compound represented by the general formula [1] has good compatibility with the resin and is unlikely to precipitate crystals, and thus is advantageous for improving sensitivity and durability. If necessary, an undercoat layer can be provided between the substrate and the organic layer to improve electrophotographic properties, image properties, and the like. Examples of the undercoat layer include polyamides, casein, polyvinyl alcohol, gelatin, and polyvinyl butyral. And the like, and metal oxides such as aluminum oxide. The material of the present invention is used not only as a hole transport material for an electrophotographic photoreceptor for a copying machine or a printer, but also for 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 with reference to the following examples. Synthesis method of compound (2) 7 parts of sodium hydroxide and 0.05 parts of cuprous chloride were added to 5 parts of 9,10-diaminophenanthracene and 23 parts of 4-bromo-biphenyl, and the mixture was heated and stirred at 220 ° C. for 30 hours. Thereafter, the mixture was cooled, extracted with 200 parts of ethyl acetate, concentrated by an evaporator, and the deposited precipitate was recrystallized from methanol. 8 parts of a gray powder were obtained. 5 parts of this powder was heated and stirred at 200 ° C. for 30 hours together with 12 parts of p-iodotoluene, 20 parts of potassium carbonate, and 0.1 part of copper powder 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 C ₅₂ H ₄₀ N ₂ Calculated (%): C: 90.13 H : 5.78
N: 4.05 Actual value (%): 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 Compound (1) was placed on a washed glass plate with an ITO electrode.
Tris (8-hydroxyquinoline) aluminum complex,
The polycarbonate resin (PC-A) was dissolved in tetrahydrofuran at a ratio of 3: 2: 5, and a light-emitting layer having a thickness of 100 nm was obtained by a spin coating method. On top of that, an alloy of magnesium and silver mixed at a ratio of 10: 1 with a film thickness of 150
1 nm was obtained to obtain an organic EL device shown in FIG.
This device emitted light of 180 cd / m ² at a DC voltage of 5 V.

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 was vacuum-deposited to form a light-emitting layer having a thickness of 30 nm, and an alloy obtained by mixing magnesium and silver at a ratio of 10: 1 to a thickness of 100 nm.
2 nm was formed to obtain an organic EL device shown in FIG.
The light emitting layer was deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device obtained the emission luminance shown in Table 2 at a DC voltage of 5 V.

Comparative Example 1 N, N'-diphenyl-N, N'-
(3-methylphenyl) -1,1′-biphenyl-4
An organic EL device was produced in the same manner as in Examples 2 to 13, except that 4′-diamine (compound 13) was used. This device obtained the emission luminance shown in Table 2 at a DC voltage of 5 V.

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

[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 was vacuum-deposited to form a light-emitting layer having a thickness of 30 nm, and an alloy obtained by mixing magnesium and silver at a ratio of 10: 1 to a thickness of 100 nm.
2 nm was formed to obtain an organic EL device shown in FIG.
The light emitting layer was deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a DC voltage of 5
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 thickness of 20 nm. Further, N, N'-diphenyl-N, N '-(3-methylphenyl) -1,1'-biphenyl-4,4'-diamine was vacuum-deposited to obtain a hole transport layer having a thickness of 30 nm. Was. Next, a tris (8-hydroxyquinoline) aluminum complex was vacuum-deposited to form a light-emitting layer having a thickness of 30 nm, and an electrode having a thickness of 100 nm was formed thereon using an alloy in which magnesium and silver were mixed at a ratio of 10: 1. Thus, an organic EL device was obtained. The hole injection layer and the light emitting layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device emitted light of about 450 cd / m ² at a DC voltage of 5 V.

Example 16 N, N'-diphenyl-N, N '-(3-methylphenyl) -1,1'- was placed on a washed glass plate with an ITO electrode.
Biphenyl-4,4'-diamine was vacuum-deposited to obtain a hole injection layer having a thickness of 50 nm. Next, a tris (8-hydroxyquinoline) aluminum complex and a compound (11)
Is deposited by vacuum evaporation at a ratio of 3: 1 to form a 50 nm-thick light-emitting layer, on which a 150-nm-thick electrode is formed using an alloy of magnesium and silver mixed at a ratio of 10: 1. 2
Was obtained. The hole injection layer and the light emitting layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This element is approximately 360 cd / m at 5 VDC.
² luminescence was obtained.

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

As shown in Table 2, the organic EL device of this example emitted high-luminance light at a low voltage, whereas the organic EL devices of Comparative Examples 1 and 2 emitted approximately half the luminance. Also,
When light emission was continuously performed at 1 mA / cm ² for all the organic EL elements, the organic EL elements of this example were able to observe stable light emission for 1000 hours or more. Degraded to half the initial light emission luminance in 100 hours. The organic EL device of the present invention achieves luminous efficiency, improved luminous brightness and longer life,
The light emitting substance, the light emitting auxiliary material, the hole transporting material, the electron transporting material, the sensitizer, the resin, the electrode material, and the like used in combination are not limited.

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

Example 19 6 g of dibromoanthanthrone, 2 g of compound (11)
Polyester resin (Byron 200: manufactured by Toyo Defense Co., Ltd.)
12 g was dispersed in a ball mill for 5 hours together with 80 g of tetrahydrofuran. This dispersion was applied on an aluminum substrate and dried to produce a single-layer electrophotographic photosensitive member having a thickness of 15 μm as 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 together with 96 g of tetrahydrofuran in a ball mill for 2 hours. This dispersion was coated on an aluminum substrate and dried to form a charge generation layer having a thickness of 0.3 μm. Next, 10 g of the compound shown in Table 3 and a polycarbonate resin (L-125)
0; Teijin Chemicals Ltd.) 10 g with dichloromethane 80 g
Was dissolved. This coating liquid was applied on the charge generating layer and dried to form a charge transporting layer having a thickness of 20 μm, thereby producing a laminated electrophotographic photosensitive member shown in FIG.

Comparative Example 3 N, N'-diphenyl-N, N'-
(3-methylphenyl) -1,1′-biphenyl-4
Except for using 4′-diamine (Compound 13), a laminated electrophotographic photosensitive member was produced in the same manner as in Examples 20 to 31.

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

Example 32 N, N'-bis (2-carbomethoxyphenyl) -3,
2,9,10-Perylenedicarboximide 2 g, polyvinyl butyral resin (BH-3: manufactured by Sekisui Chemical Co., Ltd.)
2 g together with 96 g of tetrahydrofuran in a ball mill
Time dispersed. This dispersion was coated on an aluminum substrate and dried to form a charge generation layer having a 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 on the charge generating layer and dried to form a charge transporting layer having a thickness of 20 μm, thereby producing a laminated electrophotographic photosensitive member shown in FIG.

The electrophotographic characteristics of the electrophotographic photosensitive member were measured by the following methods. Electrostatic copying paper tester (EPA-810
0; manufactured by Kawaguchi Electric Works, Ltd.), static mode 2, corona charging is -5.2 (kV), 5 (lux)
Irradiates white light, and the ratio of the initial surface potential (V ₀ ), V ₀ to the surface potential (V ₂ ) when left in a dark place for 2 seconds (dark decay rate: DDR ₂ = V ₂ / V ₀ ) , Half-exposure sensitivity (E _1/2 )
The surface potential (VR ₃ ) after 3 seconds of light exposure was examined. Table 3 shows the electrophotographic characteristics of the electrophotographic photoreceptors of Examples 18 to 32 and Comparative Examples 3 and 4.

[0062]

[Table 3]

As shown in Table 3, the electrophotographic photoreceptors of this example exhibited high chargeability and high sensitivity, whereas the electrophotographic photoreceptors of Comparative Examples 3 and 4 exhibited both chargeability and sensitivity. Was worse. Further, when the electrophotographic characteristics were measured repeatedly 10,000 times or more, all the electrophotographic photosensitive members of this example exhibited stable surface potential and sensitivity.

[0064]

According to the present invention, a compound having an excellent hole transporting ability can be obtained. The compounds provided by the present invention have higher luminous efficiency and higher brightness than conventional ones, and have excellent long-life organic EL devices and excellent initial electrophotographic properties such as sensitivity, hole transport properties, initial surface potential, and dark decay rate. Thus, an electrophotographic photoreceptor having less fatigue due to repeated use could be obtained. Since the hole transport material of the present invention has high solubility in an organic solvent, a uniform thin film can be obtained even when a hole transport layer is formed. Also, in the case of a vapor-deposited film, it is difficult to coagulate the thin film after the formation of the thin film, so that deterioration of the element can be prevented. For the above reasons, stable hole transport characteristics were obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic structure of an organic EL device used in an example.

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

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

FIG. 4 is a cross-sectional view illustrating a schematic structure of an electrophotographic photosensitive member used in an example.

FIG. 5 is a sectional view showing a schematic structure of an electrophotographic photosensitive member used in Examples and Comparative Examples.

[Explanation of symbols]

 1. Substrate 2. Electrode A3. 3. Hole injection layer Light emitting layer 5. Electron injection layer 6. Electrode B 7. Al substrate 8. Photosensitive layer 9. Charge generation layer 10. Hole transport layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshio Enoda 2-3-1 Kyobashi, Chuo-ku, Tokyo Toyo Ink Manufacturing Co., Ltd. Examiner Yoko Watanabe (56) References JP-A-6-346049 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C09K 11/06 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A hole transporting material represented by the following general formula [1]. General formula [1] [Wherein, R ^{1 to} R ⁶ each independently represent 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 R7 to R8 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] [Wherein, R ^{1 to} R ⁸ represent the same meaning as described above. ] 3. An electrophotographic photoreceptor using a charge generation material and a hole transport material on a conductive substrate, wherein the hole transport material is the hole transport material according to claim 1 or 2. An electrophotographic photosensitive member characterized by the following.