JPH10158642A - Hole transport material and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hole transport material which has excellent hole transportation capacity and durability and can be used as a photosensitive material or an organic photoconductive material by using a compound having a triphenylamine structure. SOLUTION: A compound represented by the formula (wherein R<1> to R<6> are each a (substituted) aryl, provided that at least one of them is an aryl the adjoining substituents of which form a cycloalkyl ring); and Ar<1> to Ar<3> are each a (substituted) arylene) is used. In the formula, it is desirable that R<1> , R<3> and R<5> are each an aryl the adjoining substituents of which form a cycloalkyl ring and that the aryl group having the formed cycloalkyl ring is (substituted) tetrahydronaphthalene. This material is obtained by for example reacting tris(p-bromophenyl)amine with a 5-8 molar time amount of a substituted aromatic diamine compound at 200 deg.C for 50hr in the presence of a catalyst such as potassium carbonate or copper.

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 triphenylamine structure, and the triphenylamine compound can be used as a photosensitive material or an organic photoconductive material. It can be used as a hole transporting material for an organic electroluminescence (EL) element or an electrophotographic photosensitive member used for the above.

[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
No. 19,132), stilbene derivatives (JP-A-58-1)
No. 90,953, JP-A-59-195,658) and the like.

[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. In general, an EL is composed of a light emitting layer and a pair of counter electrodes sandwiching the light emitting layer. In light emission, when an electric field is applied between both electrodes, electrons are injected from the cathode side and holes are injected from the anode side. Further, the electrons are recombined with holes in the light emitting layer, and energy is emitted as light when the energy level returns from the conduction band to the valence band.

[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). This method uses a metal chelate complex for a phosphor layer and an amine compound for a hole injection layer to obtain high-luminance green light emission, and has a luminance of 1000 at a DC voltage of 6 to 7 V.
(Cd / m ² ) and a maximum luminous efficiency of 1.5 (lm / W), which is close to the practical range.

An organic EL device is a device having a light emitting layer containing an organic fluorescent compound between a metal cathode layer and a transparent anode layer. Also, in order to obtain high-luminance light emission at low voltage,
An element is formed by adding an electron injection layer and a hole injection layer. In these organic EL elements, excitons are generated by recombination of electrons injected from the cathode and holes injected from the anode, and light is emitted in the process of extinguishing the excitons (Japanese Patent Application Laid-Open No. H10-163,197). 5
9-194393, JP-A-63-295695). However, if light emission is continued for a long time by applying a DC voltage, crystallization of an organic compound or the like is promoted, a leak current easily flows through the element, and the element is destroyed. Therefore, as a hole transporting material used for the hole injection layer, 4,4 ′, 4 ″ -tris (N, N′-diphenylamino) triphenylamine (TDATA), 4,4 ′,
It is improved by using a compound such as 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) (JP-A-4-30868).
No. 8). These compounds are difficult to crystallize because the molecules are twisted to form a three-dimensional shape, and are excellent in thin film forming property, but are not sufficient. Therefore, there is a problem that the element is easily deteriorated when light is emitted for a long time.

As described above, the organic EL devices up to now are:
Luminous luminance and luminous stability during repeated use are not yet sufficient. For the development of organic EL devices having higher luminous luminance, high luminous efficiency and excellent stability during repeated use, excellent holes are required. The development of a durable hole transporting material having a transporting ability is desired.

Further, as a technique utilizing a hole transport material, an electrophotographic photosensitive member can be mentioned. 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 such an electrophotographic photoreceptor are that an appropriate potential is maintained in a dark place, that there is little discharge of charges in a dark place, and that charges are quickly discharged by light irradiation. And the like. Conventional electrophotographic photoreceptors have used inorganic photoconductors such as selenium, selenium alloys, zinc oxide, cadmium sulfide, and tellurium. These inorganic photoconductors are
Although it has advantages such as high durability and a large number of printing presses, problems such as high manufacturing cost, poor workability, and toxicity are pointed out. To overcome these drawbacks, photoreceptors using organic compounds have been developed.However, electrophotographic photoreceptors using conventional organic photoconductive materials as hole-transporting materials have had a problem of chargeability, sensitivity and At present, electrophotographic characteristics such as residual potential are not always satisfied, and it has been desired to develop a hole transporting material having excellent charge transporting ability and durability.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a durable hole transporting material having excellent hole transporting ability, and further to use this hole transporting material. Accordingly, it is an object of the present invention to provide a long-life organic EL element, an electrophotographic photoreceptor having excellent stability during repeated use, and the like.

[0009]

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 an organic material prepared by using the same. The inventors have found that the device characteristics such as an EL device or an electrophotographic photosensitive member and the stability upon repeated use are 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 represent an aryl group which may have a substituent, provided that at least one of R ^{1 to} R ⁶ represents an aryl group in which adjacent substituents form a cycloalkyl ring. Represent. Ar ^{1 to} Ar ³ represent an arylene group which may have a substituent. ]

Further, the present invention provides a compound represented by the general formula [1]:
A hole transport material in which R ¹ , R ³ and R ⁵ are aryl groups in which adjacent substituents form a cycloalkyl ring.

Further, the present invention is the above hole transport material, wherein the aryl group in which adjacent substituents form a cycloalkyl ring is a tetrahydroxynaphthalene group which may have a substituent.

Further, 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 formed between a pair of electrodes, wherein at least one layer contains the above-mentioned hole transport material. The organic electroluminescent device is a layer.

Further, the present invention provides an organic electroluminescent device comprising an organic compound thin film including a hole transport layer and a light emitting layer formed between a pair of electrodes, wherein the hole transport layer comprises the hole transport material. It is an organic electroluminescence element which is a layer containing.

Further, the present invention provides an organic electroluminescence device comprising a light emitting layer or a plurality of organic compound thin films including the light emitting layer formed between a pair of electrodes, wherein the light emitting layer contains the above hole transport material. The organic electroluminescent device is a layer.

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

BEST MODE FOR CARRYING OUT THE INVENTION

R ^{1 to} R ^{6 in} the general formula [1] are aryl groups, and include phenyl, tolyl, naphthyl, anthranyl, phenanthrenyl, fluorenyl, acenaphthyl, azulenyl, heptalenyl, acenaphthenyl, Pyrenyl group, biphenyl group, 4-ethylbiphenyl group, terphenyl group, quarterphenyl group, benz [a] anthranyl group, triphenylenyl group, 2,3
-A benzofluorenyl group and a 3,4-benzopyrenyl group. Ar ^{1 to} Ar ³ are an arylene group, and include a phenylene group, a 2-methylphenylene group, a naphthylene group, an anthranylene group, a phenanthrenylene group, a fluorenylene group, an acenaphthylene group, a pyrenylene group, a biphenylene group, and 2,2′-dimethyl Examples include a biphenylene group, a 3,3′-dichlorobiphenylene group, a terphenylene group, and a quarterphenylene group. The aliphatic ring formed by adjacent substituents is an aliphatic ring having 4 to 8 carbon atoms, such as a cyclobutyl ring, a cyclopentyl ring, a cyclohexyl ring, a cycloheptyl ring, a cyclooctyl ring, and the like.

Representative examples of the substituents which may be substituted on the aryl group represented by the general formula [1] and the arylene group in the present invention include the following substituents. Halogen atoms include fluorine, chlorine, bromine and iodine. Examples of the substituted or unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a sec-butyl group, a te
rt-butyl group, pentyl group, hexyl group, heptyl group, octyl group, stearyl group, trichloromethyl group,
Trifluoromethyl group, cyclopropyl group, cyclohexyl group, 1,3-cyclohexadienyl group, 2-cyclopenten-1-yl group, 2,4-cyclopentadiene-1
-Iridenyl group and the like. Examples of the substituted or unsubstituted alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, a sec-butoxy group and a tert-
Butoxy, pentyloxy, hexyloxy, stearyloxy, trifluoromethoxy and the like. Examples of the substituted or unsubstituted thioalkoxy group include a methylthio group, an ethylthio group, a propylthio group, a butylthio group, a sec-butylthio group, a tert-butylthio group,
Examples include a pentylthio group, a hexylthio group, a heptylthio group, and an octylthio group.

The mono- or di-substituted amino groups include methylamino, dimethylamino, ethylamino, diethylamino, dipropylamino, dibutylamino, diphenylamino, bis (acetooxymethyl)
There are an amino group, a bis (acetooxyethyl) amino group, a bis (acetooxypropyl) amino group, a bis (acetooxybutyl) amino group, a dibenzylamino group and the like. Examples of the substituted or unsubstituted aryloxy group include a phenoxy group, a p-tert-butylphenoxy group, and a 3-fluorophenoxy group. Examples of the substituted or unsubstituted arylthio group include a phenylthio group and a 3-fluorophenylthio group. Examples of the substituted or unsubstituted aryl group include phenyl, biphenyl, triphenyl, terphenyl, 3-nitrophenyl, 4-methylthiophenyl, 3,5-dicyanophenyl, o
-, M- and p-tolyl groups, xylyl groups, o-, m-
And p-cumenyl group, mesityl group, pentalenyl group,
Indenyl, naphthyl, azulenyl, heptalenyl, acenaphthylenyl, phenalenyl, fluorenyl, anthryl, anthraquinolyl, 3-methylanthryl, phenanthryl, triphenylenyl, pyrenyl, chrysenyl, 2-ethyl- 1-chrysenyl group, picenyl group, perylenyl group, 6-chloroperylenyl group, pentaphenyl group, pentacenyl group, tetraphenylenyl group, hexaphenyl group, hexacenyl group,
Rubicenyl group, coronenyl group, trinaphthylenyl group, heptaphenyl group, heptaenyl group, pyranthenyl group,
Ovalenyl group and the like.

The substituted or unsubstituted heterocyclic group includes
Thionyl group, furyl group, pyrrolyl group, imidazolyl group,
Pyrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolyl, quinolyl, isoquinolyl, phthalazinyl, quinoxalinyl, quinazolinyl, carbazolyl, acridinyl, phenazinyl, furfuryl, isothiazolyl, isoxazolyl , A furazanyl group, a phenoxazinyl group, a benzothiazolyl group, a benzooxazolyl group, a benzimidazolyl group, a 2-methylpyridyl group, a 3-cyanopyridyl group, and the like, but are not specifically limited to the above substituents.

Adjacent substituents may form a 5- to 7-membered cycloalkyl, aryl, or heterocyclic ring which may contain an oxygen atom, a nitrogen atom, a sulfur atom and the like. A substituent may be further present at any position on the ring, and typical examples thereof include a phenyl group, a fluorenyl group, an anthryl group, an anthraquinonyl group, a 3-methylanthryl group, a phenanthryl group, a triphenylenyl group and a pyrenyl group. , A chrysenyl group, a 2-ethyl-1-chrysenyl group, a picenyl group, a perylenyl group, a 6-chloroperylenyl group, a pentaphenyl group, a pentacenyl group, a tetraphenylenyl group, a hexaphenyl group, a hexacenyl group,
Rubicenyl group, coronenyl group, trinaphthylenyl group, heptaphenyl group, heptaenyl group, pyranthenyl group,
Ovalenyl group and the like. As the heterocycle, a thionyl group,
Furyl, pyrrolyl, imidazolyl, pyrazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, indolyl, quinolyl, isoquinolyl, phthalazinyl, quinoxalinyl, quinazolinyl, carbazolyl, acridinyl, phenazinyl , Furfuryl, isothiazolyl, isoxazolyl, furazanyl, phenoxazinyl, benzothiazolyl, benzoxazolyl, benzimidazolyl, 2-methylpyridyl, 3-cyanopyridyl and the like.

The compound represented by the general formula [1] of the present invention can be synthesized, for example, by the following method. In a nitrobenzene solvent, a 5- to 8-fold molar substitution of a substituted aromatic diamine compound is added to tris (p-bromophenyl) amine.
By reacting with a catalyst such as potassium carbonate or copper at 200 ° C. for 50 hours, an aromatic amine compound represented by the general formula [1] is synthesized.

Representative examples of the compound represented by the general formula [1] are specifically shown in Table 1, but are not limited thereto.

[0023]

[Table 1]

[0024]

[0025]

[0026]

[0027]

[0028]

The hole transporting material of the present invention may be used in a mixture with other hole or electron transporting compounds in the same layer. Since the compound of the present invention has excellent hole transporting properties, it can be used very effectively as a hole transporting material.

An organic EL device is a device in which a single or multilayer organic thin film is formed between an anode and a cathode. In the case of a single layer type, a light emitting layer is provided between an anode and a cathode. The light-emitting layer contains a light-emitting material and may further contain a hole-transport material or an electron-transport material for transporting holes injected from an anode or electrons injected from a cathode to the light-emitting material. The light emitting material may have a hole transporting property or an electron transporting property. The multilayer type includes (anode / hole injection layer / light-emitting layer / cathode), (anode / light-emitting layer / electron injection layer /
There is an organic EL device having a multilayer structure of (cathode) and (anode / hole injection layer / emission layer / electron injection layer / cathode). The compound of the general formula [1] can be used in any device 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 injection layer and the light emitting layer.
Since the hole transport material of the present invention has a function of injecting holes from the anode and a function of transporting injected holes, it can be used for any of the two or more hole injection layers. You can do it. Since the thin film formed of the compound represented by the general formula [1] has an amorphous property, it is advantageous in long-term storage when the thin film is formed, light emission life when the element is driven, and the like. Further, the compound represented by the general formula [1] has good adhesion to a metal electrode such as ITO and has a low ionization potential of the film, which is advantageous for hole injection from the anode. When two or more layers are used, it is more advantageous to use the compound of the general formula [1] for the hole injection layer on the metal electrode (anode) side.

In the light emitting layer, if necessary, a light emitting material, a doping material, a hole transporting material for transporting carriers and an electron transporting material may be used in addition to the compound of the general formula [1] of the present invention. it can. In the case of a two-layer structure, the light emitting layer and the hole injection layer are separated. With this structure, the efficiency of hole injection from the hole injection layer to the light emitting layer is improved, and the light emission luminance and the light emission efficiency can be increased. In this case, in order to emit light, it is desirable that the light emitting substance used in the light emitting layer itself has an electron transporting property, or that an electron transporting material is added to the light emitting layer. Another layer configuration includes a two-layer structure including a light emitting layer and an electron injection layer. In this case, it is desirable that the light emitting material itself has a hole transporting property, or that the hole transporting material is added to the light emitting layer.

The three-layer structure has a light emitting layer, a hole injection layer, and an electron injection layer to improve the efficiency of recombination of holes and electrons in the light emitting layer. 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. In such an element having a multilayer structure, a light emitting material, a doping material, a hole transport material for transporting carriers, and an electron transport material can be used in combination, if necessary. In addition, each of the hole injection layer, the light emitting layer, and the electron injection layer may be formed of two or more layers.

As the conductive material used for the anode of the organic EL element, those having a work function of more than 4 eV are suitable, and include carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, and 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 smaller than 4 eV are preferable, and magnesium, calcium, tin, lead, titanium,
Yttrium, lithium, ruthenium, manganese and the like and alloys thereof are used. Alloys include, but are not limited to, magnesium / silver, magnesium / indium, lithium / aluminum, and the like. The anode and the cathode may be formed of two or more layers if necessary.

In the organic EL device, it is desirable that at least one of them is sufficiently transparent in the emission wavelength region of the device in order to emit light efficiently. Further, it is desirable that the substrate is also transparent. The transparent electrode is set so as to secure a predetermined translucency by a method such as vapor deposition or sputtering using the above conductive material. The electrode on the light emitting surface desirably has a light transmittance of 10% or more. The substrate has mechanical and thermal strength, and is not limited as long as it is transparent.Examples include a glass substrate, a transparent resin such as polyethylene, polyethersulfone, and polypropylene, and a plate-like, Any of a film form may be used.

Each layer of the organic EL device according to the present invention can be formed by any of a dry film forming method such as vacuum evaporation and sputtering and a wet film forming method 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 material for forming each layer is dissolved or dispersed in an appropriate solvent such as chloroform, tetrahydrofuran, dioxane or the like to form a thin film.
The solvent may be any. In any of the thin films, a suitable resin or additive may be used to improve film forming properties, prevent pinholes in the film, and the like. Examples of the resin used in the present invention include insulating resins such as polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate, and cellulose, poly-N-vinyl carbazole, and polysilane. And a conductive resin such as polythiophene and polypyrrole. Examples of the additive include an antioxidant, an ultraviolet absorber, and a plasticizer.

The light emitting material or doping material usable in the organic EL device of the present invention includes anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone,
Naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, aldazine, bisbenzoxazoline, bisstyryl, pyrazine, cyclopentadiene, quinoline metal complex, aminoquinoline metal complex, benzoquinoline metal complex, imine, diphenylethylene, vinyl anthracene , Diaminocarbazole, triphenylamine, benzidine-type triphenylamine, styrylamine-type triphenylamine, diamine-type triphenylaminepyran, thiopyran, polymethine, merocyanine, imidazole chelated oxinoid compounds, quinacridone, rubrene, and derivatives thereof. However, the present invention is not limited to these.

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 material. 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 the ability to transport electrons, has an excellent electron injection effect on the light emitting layer or the light emitting material, and has a hole injection layer or a hole transporting function for 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. Alternatively, the electron transporting material may be sensitized by adding an electron accepting material to the hole transporting material and the electron donating material to the electron transporting material.

The compound of the general formula [1] of the present invention can be used for any layer. In addition to the compound of the general formula [1], a luminescent material, a doping 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 stable against heat and current, and can obtain practically usable emission luminance at a low drive voltage. I was able to. The organic EL element of the present invention can be used for flat panel displays such as wall-mounted televisions,
The flat illuminant 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 very 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 material, can transport charges generated by absorbing light extremely efficiently, and can provide a photoreceptor with 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 in which a charge generation material and, if necessary, a charge transport material are dispersed 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.

Examples of the charge generating material include bisazo, quinacridone, diketopyrrolopyrrole, indigo, perylene,
Organic compounds such as perinone, polycyclic quinone, squarylium salt, azurenium salt, phthalocyanine, and naphthalocyanine; and inorganic materials such as selenium, selenium-tellurium alloy, cadmium sulfide, zinc oxide, and amorphous silicon.

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 μm to 50 μm in the case of a single layer type photoreceptor, and 0.05 μm in the case of a multilayer type photoreceptor.
1 μm to 5 μm, preferably 0.1 μm to 1 μm, and the hole transport layer is 5 μm to 50 μm, preferably 1 μm to 50 μm.
0 μm to 20 μm is suitable.

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, but not limited to, 100% by weight or less based on the charge generation material or the hole transport material. 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 transporting layer is formed by a method of applying only the hole transporting material, a coating solution in which the hole transporting material is dissolved in an insulating resin, or a dry film forming method such as vapor deposition.
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]. Furthermore, even when an insulating resin is used in combination to improve heat resistance and abrasion resistance, the compatibility with other resins is good, and the formed thin film is unlikely to precipitate as crystals, so sensitivity and durability are improved. This is advantageous for the improvement of

If necessary, an undercoat layer may 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, and gelatin. And resins such as polyvinyl butyral and metal oxides such as aluminum oxide. The material of the present invention can be used not only as a hole transport material such as an organic EL device or an electrophotographic photosensitive member, but also in any field of an organic photoconductive material such as a photoelectric conversion device, a solar cell, and an image sensor.

[0049]

The present invention will be described below in more detail with reference to examples. According to the DSC analysis, the compound represented by the general formula [1] of the present invention has a glass transition temperature of 100.
° C, melting point 250 ° C or higher, decomposition point 300 ° C or higher, and conventionally used as an amorphous hole transporting material 4,
4 ', 4 "-tris [N- (3-methylphenyl) -N
[Phenylamino] triphenylamine has a higher glass transition temperature, melting point, and decomposition point, indicating that the organic EL device has high heat resistance as a hole transporting material. In addition, all the compounds represented by the general formula [1] have low crystallinity and are non-crystalline compounds, so that they have good adhesion to the anode substrate and the organic thin film layer, and can be used in an environment as an organic thin film. There is also a great advantage in terms of durability, life time when used as an organic EL element, and light emission life.

Example 1 Compound (1) was vacuum-deposited on a washed glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 30 nm. Next, a tris (8-hydroxyquinoline) aluminum complex was vacuum-deposited to form a 50-nm-thick light-emitting layer, on which a 150-nm-thick electrode was formed using an alloy of magnesium and silver mixed at a ratio of 10: 1. Thus, an organic EL device was obtained.
The hole injection layer and the light emitting layer are formed in a vacuum of 10 ^-6 Torr,
The deposition was performed at a substrate temperature of room temperature. This device has a luminous luminance of 120 (cd / m ² ) at a DC voltage of 5 V and a luminous efficiency of 1.
2 (lm / W) was obtained.

Example 2 An organic EL device was manufactured in the same manner as in Example 1, except that the hole injection layer was formed by spin coating the compound (2) dissolved in chloroform. This element has a DC voltage of 5
Luminance luminance 130 (cd / m ² ) at V, luminous efficiency 1.9
(Lm / W) was obtained.

Example 3 A compound (3) was vacuum-deposited on a washed glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 30 nm. Next, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) was vacuum-deposited to obtain a 10-nm-thick hole transport layer. Further, a compound (19) represented by the following structure is vacuum-deposited to a thickness of 50 nm.
Then, a 150 nm-thick electrode was formed using an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to obtain an organic EL device. The hole injection layer and the light emitting layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device had a light emission luminance of 270 (cd / m ² ) and a light emission efficiency of 2.1 (lm / W) at a DC voltage of 5 V.

Embedded image Compound (19)

Examples 4 to 21 Compounds shown in Table 1 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. Next, the compound (16) was vacuum-deposited to form a 50 nm-thick light-emitting layer, on which a 100-nm-thick electrode was formed using an alloy in which magnesium and silver were mixed at a ratio of 10: 1 to form an organic EL device. Obtained. 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 characteristics shown in Table 2 at a DC voltage of 5 V.

[0054]

[Table 2]

Example 22 Compound (3) was vacuum-deposited on a washed glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 40 nm. Next, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) was vacuum-deposited to obtain a 10-nm-thick hole transport layer. Further, a tris (8-hydroxyquinoline) aluminum complex is vacuum-deposited to form a 50-nm-thick light-emitting layer, and a compound (16) is further vacuum-deposited to form a 50-nm-thick electron-injection layer. An electrode having a thickness of 150 nm was formed from an alloy in which aluminum and lithium were mixed at a ratio of 25: 1 to obtain an organic EL device. The hole injection layer and the light emitting layer are 10 ^-6 To
Vapor deposition was performed at a substrate temperature of room temperature in a vacuum of rr. This element has a light emission luminance of 500 (cd /
m ² ) and a luminous efficiency of 2.7 (lm / W).

Example 23 Compound (6) was vacuum-deposited on a washed glass plate with an ITO electrode to obtain a hole injection layer having a thickness of 40 nm. Next, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) was vacuum-deposited to obtain a 10-nm-thick hole transport layer. Further, the following compound (20) was vacuum-deposited to form a 50-nm-thick light-emitting layer, and a tris (8-hydroxyquinoline) aluminum complex was further vacuum-deposited to form a 50-nm-thick electron injection layer. Then, an electrode having a thickness of 150 nm is formed of an alloy in which magnesium and silver are mixed at a ratio of 10: 1, and the organic EL is formed.
An element was obtained. The hole injection layer and the light emitting layer are 10 ^-6 Torr
Vacuum was deposited in a vacuum at a substrate temperature of room temperature. This device has a light emission luminance of 400 (cd / m ² ) at a DC voltage of 5 V,
A luminous efficiency of 2.4 (lm / W) was obtained.

Embedded image Compound (20)

Example 24 Compound (3) and rubrene were vacuum-deposited at a weight ratio of 20: 1 on a washed glass plate with an ITO electrode to form a film having a thickness of 60%.
As a result, a hole injection type light emitting layer having a thickness of nm was obtained. Furthermore, Tris (8-
(Hydroxyquinoline) aluminum complex is vacuum-deposited to form an electron injection layer having a thickness of 20 nm, on which an alloy of magnesium and silver mixed at a ratio of 10: 1 to a thickness of 150 nm.
Was formed to obtain an organic EL device. The hole injection layer and the light emitting layer were deposited in a vacuum of 10 ^-6 Torr at a substrate temperature of room temperature. This device has a light emission luminance of 660 (cd / m ² ) at a DC voltage of 5 V and a light emission efficiency of 3.4 (lm / m ² ).
W) was obtained.

Comparative Example 1 In place of the compound (1) in the hole injection layer, 4,4 ′, 4 ″-
Example 1 except that tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine was used.
An organic EL device was prepared in the same manner as described above. This element
At a DC voltage of 5 V, a light emission luminance of about 160 (cd / m ² ) and a light emission efficiency of 1.2 (lm / W) were obtained.

Comparative Example 2 Instead of compound (3) in the hole injection layer, 4,4 ′, 4 ″-
Example 2 except that tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine was used.
An organic EL device was prepared in the same manner as in Example 2. This device has a light emission luminance of about 220 (cd / m ² ) at a DC voltage of 5 V,
A luminous efficiency of 1.5 (lm / W) was obtained.

For all the organic EL devices shown in this example, continuous emission was performed at 3 (mA / cm ² ).
Although the luminance of 50% or more of the initial luminance could be observed for 1000 hours or more, the devices of Comparative Example 1 and Comparative Example 2 were continuously illuminated under the same conditions.
0% or less, and the number of dark spots also increased. The reason for the above results is that since the compound of the present invention is a non-planar compound, it is possible to form a non-crystalline thin film when forming a thin film, and that many condensed aromatic compounds are contained in the compound. Since it has a ring, the hole transporting property is improved, and the organic E
The hole injection property and the hole transport property of the L element are improved. Further, the heat resistance of the hole transport material is also improved, so that the resistance to heat generation during continuous light emission is also improved. Since the compound of the general formula [1] forms a cycloalkyl ring between adjacent substituents of the aryl group, the non-crystallinity is increased, and the adhesion between the hole injection from the substrate and the substrate is also improved. Will do. The organic EL device of the present invention achieves improvement in luminous efficiency, luminous luminance and long life, and is used together with a luminescent material, a doping material, a hole transport material, an electron transport material, a sensitizer, It does not limit the resin, the electrode material and the like, and the element manufacturing method.

Next, examples in which the hole transport material of the present invention is used for an electrophotographic photosensitive member will be described below.

Example 25 4 g of ε-type copper phthalocyanine, 2 g of compound (3) and 14 g of a polyester resin (Toyobo: Byron 200) were dispersed together with 80 g of tetrahydrofuran in a ball mill for 5 hours. This dispersion was coated on an aluminum substrate and dried to produce a 20 μm-thick single-layer electrophotographic photosensitive member.

Example 26 6 g of dibromoanthanthrone, 2 g of compound (6) and 12 g of polyester resin (Toyobo: Byron 200) were dispersed together with 80 g of tetrahydrofuran in a ball mill for 5 hours. This dispersion was coated on an aluminum substrate and dried to produce a 20 μm-thick single-layer electrophotographic photosensitive member.

Example 27 N, N'-bis (2,6-dichlorophenyl) -3,
2 g of 4,9,10-perylenedicarboximide and 2 g of polyvinyl butyral resin (Sekisui Chemical: BH-3) 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 compound (10) and a polycarbonate resin (Teijin Chemical:
Panlite L-1250) 10 g with dichloromethane 80
g. This coating solution was applied on the charge generation layer and dried to form a 20 μm-thick hole transport layer, thereby producing a laminated electrophotographic photoreceptor.

Examples 28 to 45 2 g of τ-type metal-free phthalocyanine and 2 g of polyvinyl butyral resin (Sekisui Chemical: BH-3) were dispersed together with 96 g of tetrahydrofuran in a ball mill for 2 hours. This dispersion is coated on an aluminum substrate and dried to a thickness of 0.3 μm.
m of charge generation layers were produced. Next, Compound 1 shown in Table 3
0 g, polycarbonate resin (Teijin Chemical: Panlite L)
-1250) in 80 g of dichloromethane. This coating solution was applied on the charge generation layer and dried to form a hole transport layer having a thickness of 20 μm, thereby producing a laminated electrophotographic photosensitive member.

The electrophotographic characteristics of the electrophotographic photosensitive member were measured by the following methods. Electrostatic copying paper test equipment (Kawaguchi Electric Works:
EPA-8100), static mode 2, corona charging -5.2 (kV), 5 (lux) white light irradiation, initial surface potential (V0), V0 when left in a dark place for 2 seconds Surface potential (V2) ratio (dark decay rate: DDR)
₂ = V2 / V0), the half-dew sensitivity (E1 / 2) and the surface potential (VR3) three seconds after light exposure were examined from the time when the charge amount decreased to half of the initial value after light exposure. Table 3 shows the electrophotographic characteristics of the electrophotographic photosensitive member of this example.

[0067]

[Table 3]

All the electrophotographic photoreceptors shown in this embodiment have surface potentials before and after repeated use of 10,000 times or more.
The electrophotographic characteristics such as sensitivity and the rate of change in image density are within 2%, indicating that the electrophotographic photosensitive member has stable electrophotographic characteristics and can hold high quality images.

Comparative Example 3 Examples 27-44 except that 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine was used for the hole transport layer. An electrophotographic photosensitive member was prepared in the same manner as in Example 1. The electrophotographic characteristics of the electrophotographic photosensitive member were as follows: initial potential (V0) =-75 (V), potential holding ratio after two seconds (DDR2) = 90 (%) ), Half-exposure dose sensitivity (E1 / 2) = 1.0 (lux.s), residual potential (VR3) after 3 seconds = -25 (V), which is inferior to the hole transport material of the present invention. In addition, the electrophotographic characteristics such as surface potential and sensitivity and the image density before and after repeated use of the electrophotographic photoreceptor more than 10,000 times show a change rate of 10% or more, and stable high-quality images are obtained. And couldn't get it.

[0070]

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 EL devices, and excellent electrophotographic characteristics such as sensitivity, hole transport characteristics, initial surface potential, and dark decay rate. Thus, an electrophotographic photoreceptor having less fatigue due to repeated use could be obtained.

Claims (7)

[Claims] 1. A hole transporting material represented by the following general formula [1]. General formula [1] [Wherein, R ^{1 to} R ⁶ represent an aryl group which may have a substituent, provided that at least one of R ^{1 to} R ⁶ represents an aryl group in which adjacent substituents form a cycloalkyl ring. Represent. Ar ^{1 to} Ar ³ represent an arylene group which may have a substituent. ] 2. The hole transport material according to claim ¹ , wherein, in the general formula [1], R ¹ , R ³ and R ⁵ are an aryl group in which adjacent substituents form a cycloalkyl ring. 3. The hole transport material according to claim 1, wherein the aryl group in which adjacent substituents form a cycloalkyl ring is a tetrahydroxynaphthalene group which may have a substituent. 4. An organic electroluminescent device comprising a light emitting layer or a plurality of organic compound thin films including a light emitting layer formed between a pair of electrodes, wherein at least one layer is a hole transporter according to claim 1. An organic electroluminescent element which is a layer containing a material. 5. An organic electroluminescence device in which an organic compound thin film including at least a hole injection layer and a light emitting layer is formed between a pair of electrodes, wherein the hole injection layer is any one of claims 1 to 3. An organic electroluminescence device, which is a layer containing the hole transporting material. 6. An organic electroluminescence device in which a light emitting layer or a plurality of organic compound thin films including the light emitting layer is formed between a pair of electrodes, wherein the light emitting layer is a hole transporting material according to claim 1. An organic electroluminescent element which is a layer containing a material. 7. An electrophotographic photoreceptor comprising a charge generation material and a hole transport material on a conductive support,
An electrophotographic photosensitive member, wherein the hole transport material is the hole transport material according to any one of claims 1 to 3.