JP2000347432A - Electric charge transferring material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electric charge transferring material stable without crystallization, capable of transferring an electric charge at room temperature, large in mobility of a charge, easy in alignment and forming film and showing no fluidity by constituting the material of the polymer of a polymerizable liquid crystal composition containing virgate liquid crystals having polymerization capability. SOLUTION: This charge transferring material comprises the polymer of a polymerizable liquid crystal composition containing virgate liquid crystals having polymerization capability. The liquid crystal having polymerization capability is preferably a cyclic alcohol, single-functional acrylate or single- functional methacrylate having a crystalline bone structure of at least two six-member rings in one molecule. As the single-functional acrylate or methacrylate, the compounds shown by the formula are exemplified. In the formula, X is hydrogen atom or methyl group; (n) is an integer of 0 or 1; (p) is an integer of 1-4; Z is hydrogen or a halogen atom or a cyano, 1-20C alkyl, alkoxy, alkenyl or alkenyloxy group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge transporting material useful for an electronic device such as an electrophotographic photoreceptor, an organic light emitting device, a photoelectric conversion device, and an image recording device. And a charge transport material comprising a polymer of a polymerizable liquid crystal composition containing a polymerizable rod-shaped liquid crystal capable of transporting both, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, many inorganic materials such as amorphous Se and Si and low-molecular or high-molecular organic materials have been known as charge transport materials. In particular, organic charge transport materials are widely used mainly for electrophotographic photoreceptors because of their low toxicity and low production cost.

[0003] Conventional organic charge transport materials are low-molecular-weight hole transport materials represented by triphenylmethane, triphenylamine and carbazole derivatives; low-molecular electron transport materials represented by trinitrofluorenone, diphenoquinone and derivatives thereof. Examples include a transport material, a charge transporting polymer represented by polyvinyl carbazole, polysilane, and the like. A low molecular hole transport material or an electron transport material is dispersed in a polymer such as polycarbonate to form a film,
Alternatively, a film is formed by a method such as vacuum evaporation, and a printer,
It is used as a charge transport layer of an electrophotographic photosensitive member such as a copying machine or an organic light emitting device. The charge transporting polymer is
The film is formed alone or mixed with other materials, and used as a charge transport layer.

In most cases, the outermost layer of the electrophotographic photoreceptor is provided with a charge transport layer made of a molecular dispersion polymer in which a charge transport material is dispersed in a thermoplastic resin such as polycarbonate. However, the abrasion resistance of these charge transporting layers is not sufficient, and when used as an electrophotographic photoreceptor such as a copying machine or a printer, the photoreceptor wears out due to friction with a developing roll, paper, blades, etc. There was the problem of being short.

On the other hand, an organic light-emitting device uses an amorphous charge-transporting layer obtained by depositing a charge-transporting substance.
The thermal stability of the charge transport layer is not sufficient, which is a factor that hinders the longevity of the organic light emitting device.

[0006] Thus, a new charge transporting material that solves these problems and has good charge transporting ability has been demanded.

As a solution to the problem of such an organic charge transport material, JP-A-9-316442 and JP-A-10-312711 propose liquid crystal charge transport materials. The liquid crystal charge transport materials disclosed in these publications are such that a rod-like liquid crystal material exhibits a large hole and electron mobility at a temperature at which a smectic phase is exhibited, and uses this as a charge transport material. The application possibility to an element, a thin film transistor, a sensor, etc. is shown. Further, it has been shown that this liquid crystalline charge transporting material can transport both holes and electrons, and for example, when used for an organic light emitting device, the layer configuration of the device can be simplified.

However, the materials disclosed in these publications have a high liquid crystal phase transition temperature. Therefore, when these materials are used as a charge transporting material, the entire device must be kept at a high temperature. It was not practical. In addition, since these materials have fluidity in a liquid crystal state, they need to be sealed in a cell and sealed, for example, and have a drawback that the form of use as a charge transport material is limited. .

On the other hand, Japanese Patent Application Laid-Open No. 11-87064 discloses a charge transporting layer made of a polymer liquid crystal material which is made of discotic liquid crystal or rod-like liquid crystal, has a charge transporting ability by hopping conduction, and is capable of alignment. The disclosed photoelectric conversion element is disclosed. Also, JP-A-11-97
No. 176 discloses an organic EL using a polymer liquid crystal material which is made of a discotic liquid crystal or a rod-shaped liquid crystal, has a charge transporting property by hopping conduction, and is capable of being oriented.
An element is disclosed. However, the polymer liquid crystal materials used therefor have drawbacks such as difficulty in alignment, poor thermal stability, and high working temperature.

[0010]

The problem to be solved by the present invention is that it is stable without crystallization, exhibits a charge transporting ability at room temperature, has a large charge mobility, and is easy to align and form a film. Another object of the present invention is to provide a charge transport material that does not exhibit fluidity.

[0011]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies focusing on a polymerizable rod-like liquid crystal compound. Have been found to be able to solve the problem, and have completed the present invention.

The present invention has been made in order to solve the above problems.
(1) A charge transport material comprising a polymer of a polymerizable liquid crystal composition containing a polymerizable rod-shaped liquid crystal is provided.

In order to solve the above-mentioned problems, the present invention provides (2) a method for producing a charge transport material in which a polymerizable liquid crystal composition containing a polymerizable rod-like liquid crystal is polymerized by light irradiation or electron beam irradiation. provide.

Further, the present invention, in order to solve the above-mentioned problems, provides (3) an electronic device comprising the charge transport material described in (1) above as a constituent element.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The polymerizable rod-like liquid crystal constituting the charge transport material of the present invention is generally a polymerizable liquid crystal having a skeleton and a polymerizable functional group in a molecule recognized as a rod-like liquid crystal in this technical field. Compound. The rigid core has a ring, and this ring may be a carbon ring in which the atoms constituting the ring are only carbon or a heterocyclic ring containing atoms other than carbon. The ring may be a single ring or a condensed ring, or may have a spiro bond. Further, the ring may be saturated or aromatic, but preferably has at least one aromatic ring in one molecule.
The number of atoms constituting the ring is 3, 4, 5, 6, 7, 8,
It may be 9, 10 or more.

The ring having 3 to 5 atoms constituting the ring of the rod-shaped liquid crystal includes, for example, cyclopropane, oxirane, cyclobutane, cyclopentane, cyclopentanone, tetrahydrofuran, dioxolan-2-one, furan, pyrrole, pyrroline , Pyrrolidine, oxazole, isoxazole, thiophene, thiazole, isothiazole, thiadiazole, imidazole, imidazoline, imizazolidine, pyrazole, pyrazoline, pyrazolidine, 1,2,3-triazole, 1,2,4-triazole, tetrazole, etc. Is mentioned. Further, the ring constituting the rod-shaped liquid crystal may be a bicyclo ring such as bicyclo [2.2.2] octane.

The ring having 6 atoms constituting the ring of the rod-shaped liquid crystal includes, for example, benzene, pyridine, pyrazine, pyridazine, pyrimidine, 1,2,4-triazine,
Examples include 3,5-triazine, tetrazine, dihydrooxazine, cyclohexane, cyclohexene, cyclohexadiene, cyclohexanone, piperidine, piperazine, tetrahydropyran, dioxane, tetrahydrothiopyran, dithiane, oxathiane, dioxaborinane, and the like. Examples of the ring having 7 or more atoms constituting the rod-shaped liquid crystal ring include biphenyl, naphthalene, dioxanaphthalene, tetralen, quinoline, coumarin, quinoxaline, decalin, indane, phenylbenzoxazole, phenylbenzthiazole, phenanthrene, and dihydro. Phenanthrene, perhydrophenanthrene, dioxaperhydrophenanthrene, fluorene,
Fluorenone, cycloheptane, cycloheptatrienone, cholesteryl, and the like. Examples of the ring having a spiro bond include, for example, 1,5-dioxaspiro (5.5) undecane and 1,5-dithiaspiro (5.
5) Undecane, and the like.

These rings may have a substituent, for example, for the purpose of lowering the melting point of the rod-shaped liquid crystal. Substituents suitable for such purposes include, for example, alkyl groups, alkoxy groups, alkoxyalkenyl groups, alkylthio groups, acyloxy groups, and halogen atoms.
These substituents may include an aryl group or a heterocyclic ring, and further include an ether group, an ester group, a carbonyl group, a thioether group, a sulfoxide group, a sulfonyl group,
It may have a functional group such as an amide group.

The number of these rings in one molecule is not limited. For example, in the case of a 6-membered ring, the number is preferably 2 or more and 30 or less, more preferably 2 or more and 20 or less, and more preferably 2 or more
The following are particularly preferred. When two or more rings are linked using a linking group, such linking groups include, for example,-
O -, - S -, - COO -, - OCO -, - CH 2 CH 2
—, —CH ＝ CH—, —CH≡CH—, —OCH ₂ —,
-CO-N (R) -, - N (R) -CO -, - CH 2 O
-, -CH = CH-COO-, -OCO-CH = CH
-, A single bond, and the like (R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms).

The number of cores in one molecule is not limited, and may be a twin type having two cores, a star type or an oligomer type having a plurality of cores. The number of cores in one molecule is preferably 1 or more and 20 or less, more preferably 1 or more and 10 or less, and particularly preferably 1 or more and 6 or less.

The polymerizable functional group of the polymerizable rod-shaped liquid crystal used in the present invention reacts with the same type or different types of groups by energy such as light or heat to form a new bond. As such a polymerizable functional group, for example,
Acryloyloxy group, methacryloyloxy group, Cl
CH = CHCOO-, acrylamide group, methacrylamide group, ClCH = CHCONH-, a vinyl group, CH ₂
= CCl-, CHCl = CH-, CH 2 = CHO-, allyl group, isopropenyl group, -N = C = O, -N = C =
S, -O-C≡N, -OH, -COOH, -NH 2, epoxy group, an ethynyl group, a mercapto group, a maleimide, maleimide having a substituent, nadimide, nadimide having a substituent, and the like. Among these polymerizable functional groups, an acryloyloxy group, a methacryloyloxy group, a vinyl group, an epoxy group, an ethynyl group or a mercapto group is preferable, and an acryloyloxy group, a methacryloyloxy group, a vinyl group or an ethynyl group is more preferable.
An acryloyloxy group, a methacryloyloxy group or a vinyl group is more preferable, and a compound that is an acryloyloxy group or a methacryloyloxy group is more preferable.
Acryloyloxy groups are most preferred. Although the number of polymerizable functional groups in one molecule is not limited, it is preferably 1 or more and 10 or less, more preferably 1 or more and 5 or less. In the case of a compound having a plurality of polymerizable functional groups in one molecule, the types of the polymerizable functional groups may be different. For example, in the case of a compound having two polymerizable functional groups, one may be a methacryloyl group and the other may be a vinyl ether group.

These polymerizable functional groups may be directly bonded to the core, or may be bonded to the core via a spacer. The spacer is not particularly limited, but for example, a methylene spacer having 2 to 20 carbon atoms is preferable. The carbon atom in the methylene spacer is -O
-, -S-, -CO-, -COO-, -OCO- or-
It may be substituted with OCO-O-. The methylene spacer may be branched, for example, a swallow tail type.

The polymerizable rod-shaped liquid crystal used in the present invention may be used alone or as a mixture of two or more. When a rod-shaped liquid crystal having polymerizability is used alone, it is necessary that the compound has liquid crystallinity. On the other hand, in the case of using a mixture of a plurality of polymerizable rod-shaped liquid crystals,
It is sufficient that the compound exhibits liquid crystallinity in a mixed state, and not all compounds need to exhibit liquid crystallinity. For example, a compound having a liquid crystallinity and a compound having a core but not exhibiting liquid crystallinity exhibit liquid crystallinity by mixing. A composition may be prepared.

The liquid crystal phase of the polymerizable rod-shaped liquid crystal of the present invention or the polymerizable liquid crystal composition containing the rod-shaped liquid crystal may be used without any particular limitation as long as it is generally recognized as a liquid crystal phase in this technical field. Among them, those which exhibit a nematic phase, a chiral nematic phase, a smectic A phase, a smectic C phase, a chiral smectic C phase, and a cholesteric phase are preferable. In addition, when showing a smectic C phase (or a chiral smectic C phase), when showing a smectic A phase in a temperature region above the smectic C phase (or a chiral smectic C phase), and when showing a smectic A phase, It is preferable to show a phase series that develops a nematic phase in the temperature range above the smectic A phase, since good orientation characteristics can be obtained. There is no particular limitation on the temperature at which the rod-shaped liquid crystal having polymerizability or the polymerizable liquid crystal composition containing the rod-shaped liquid crystal exhibits a liquid crystal phase, but the alignment and other steps are facilitated. It is preferably at most 150 ° C, particularly preferably at most 100 ° C.

The polymerizable liquid crystal used in the present invention includes, for example, an acrylate of a cyclic alcohol, phenol or aromatic hydroxy compound having a liquid crystal skeleton having at least two 6-membered rings in one molecule, Monofunctional acrylates or methacrylates which are methacrylates are preferred. Such a monofunctional acrylate or monofunctional methacrylate is represented by the general formula (2)

[0026]

Embedded image

(Wherein X represents a hydrogen atom or a methyl group, and the 6-membered rings A, B and C each independently represent

[0028]

Embedded image

Wherein n is an integer of 0 or 1;
p represents an integer of 1 to 4, and Y ¹ and Y ² are each independently a single bond, —CH ₂ CH ₂ —, —CH ₂ O—, —O
CH ₂ —, —COO—, —OCO—, —C≡C—, —C
H = CH -, - CF = CF -, - (CH 2) 4 -, - CH
_{2 CH 2 CH 2 O -,} - OCH 2 CH 2 CH 2 -, - CH 2 =
CH ₃ CH ₂ — or —CH ₂ CH ₂ CH ＝ CH—, Y ³ represents a single bond, —COO—, —OCO—, Z
Represents a hydrogen atom, a halogen atom, a cyano group,
20 represents an alkyl group, an alkoxy group, an alkenyl group or an alkenyloxy group. )).

The following are examples of polymerizable rod-like liquid crystals that can be used in the present invention.

[0031]

Embedded image

[0032]

Embedded image

[0033]

Embedded image

[0034]

Embedded image

[0035]

Embedded image

[0036]

Embedded image

[0037]

Embedded image

The polymerizable liquid crystal composition used in the present invention includes:
A liquid crystal compound having no polymerizable functional group may be added in a range that does not exceed 10% by weight in the composition. As a liquid crystal compound having no polymerizable functional group,
Nematic liquid crystal compounds, smectic liquid crystal compounds, cholesteric liquid crystal compounds, and the like can be used without particular limitation as long as they are generally recognized as liquid crystals in this technical field, but as the added amount increases, the polymerizable liquid crystal composition becomes Since the mechanical strength of the optically anisotropic body obtained by photopolymerization tends to decrease, it is necessary to appropriately adjust the addition amount.

The polymerizable liquid crystal composition used in the present invention may contain a polymerizable compound that does not exhibit liquid crystallinity. As such a compound, any compound which is generally recognized as a polymer-forming monomer or a polymer-forming oligomer in this technical field may be used, and an acrylate compound is particularly preferable.

Further, a photopolymerization initiator can be added to the polymerizable liquid crystal composition of the present invention for the purpose of improving the polymerization reactivity. As the photopolymerization initiator,
For example, known benzoin ethers, benzophenones, acetophenones, benzyl ketals and the like can be mentioned. When the photopolymerization initiator is added, the amount is preferably 10% by weight or less of the polymerizable liquid crystal composition, and more preferably 5% by weight.
The following are particularly preferred.

In order to improve the storage stability of the polymerizable liquid crystal composition of the present invention, known heat stabilizers and antioxidants such as hydroquinone, hydroquinone derivatives such as hydroquinone monoalkyl ethers, Butyl catechol, pyrogallol, thiophenol compounds, nitro compounds, β-naphthylamine compounds, β-naphthol compounds, and the like can also be added. When the stabilizer is added, the amount of the stabilizer is 1% of the polymerizable liquid crystal composition.
It is preferably in the range of not more than% by weight.

When applied to an organic light emitting device, a light emitting material or a fluorescent material can be added to the polymerizable liquid crystal composition as required. As the light emitting material or the fluorescent material, for example, thiophene compounds, quinacridone derivatives, rubrene, coumarin compounds, styryl dyes,
Triphenylamine derivatives, oxadiazole derivatives,
Anthracene derivative, phenylanthracene derivative, 8
Metal complex dyes having quinolinol or a derivative thereof as a ligand, diphenylethylene derivatives, peyrene, coronene, tetraarylethene, and the like.

Next, a method for producing a charge transporting material using the polymerizable rod-like liquid crystal or polymerizable liquid crystal composition of the present invention will be described.

The polymerizable rod-shaped liquid crystal or polymerizable liquid crystal composition of the present invention is irradiated with an energy beam such as an electron beam or an ultraviolet ray at a temperature at which a liquid crystal phase is exhibited, thereby polymerizing the polymer and polymerizing the polymer. By immobilization, a charge transport material can be manufactured. After the polymerizable rod-shaped liquid crystal or polymerizable liquid crystal composition of the present invention is applied to a substrate, it is polymerized, or a cell is formed using two or more substrates and sealed in the cell. , May be polymerized. Further, after dripping on a substrate with a dispenser or the like, another substrate may be stacked and then polymerized.

The application to the substrate may be a method of applying the polymerizable liquid crystal composition of the present invention as it is, or a method of applying a coating solution obtained by dissolving the polymerizable liquid crystal composition in a solvent, followed by drying.

As the solvent used in the latter method, known and commonly used solvents can be used. Such solvents include, for example, acetone, methyl ethyl ketone, cyclohexanone, cyclopentanone, cycloheptanone, 2-
Ketones such as heptanone, methyl isobutyl ketone and butyrolactone; methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, tert
Alcohols such as butyl alcohol, pentanol, heptanol, octanol, nonanol and decanol; ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether and dioxane. Ters: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether;
Alcohol ethers such as propylene glycol monopropyl ether;

Ethyl formate, propyl formate, butyl formate,
Methyl acetate, ethyl acetate, butyl acetate, propyl acetate,
Esters such as methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, propyl butyrate; 2
-Methyl oxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate, butyl 2-oxypropionate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, 2- Monocarboxylic acid esters such as butyl methoxypropionate; cellosolve esters such as cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate; propylene glycol; Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate Nguriko - Le acids;

Diethylel glycol monomethyl ether, diethylol glycol monoethyl ether, diethylol glycol dimethyl ether, diethylol glycol
Diethylene glycols such as diethyl ether and diethyl glycol glycol methyl ethyl ether; trichloroethylene, a fluorocarbon solvent, hydrochlorofluoro.
Carbon (Hydro Chloro Fluoro Carbon; HCFC),
Hydro Fluoro Carbo
n; halogenated hydrocarbons such as HFC); perfluorinated solvents such as perfluorooctane; aromatics such as toluene and xylene; dimethylacetamide, dimethylformamide, N-methylacetamide, N-methylpyrrolidone And polar solvents such as Among these solvents, it is preferable to use a solvent having higher safety from the viewpoint of safety for the human body. These solvents may be used alone or in combination of two or more. The mixing ratio of the solvent can be appropriately adjusted as necessary, such as the required film thickness when applying the polymerizable composition to the substrate, the application conditions, and the film thickness after polymerization.

Examples of the coating method include wire bar coating, spin coating, roll coating, dip coating, spray coating, extrusion coating, car coating, and the like.
Known and commonly used coating methods such as printing, die coating, print coating, or dipping and pulling can be widely used. Among these coating methods, spin coating and die coating are preferred.

The substrate on which the polymerizable rod-shaped liquid crystal or the polymerizable liquid crystal composition of the present invention is applied, or the substrate constituting the cell in which the polymerizable rod-shaped liquid crystal or the polymerizable liquid crystal composition is filled, may be an organic material, an inorganic material or an inorganic material. Any material can be used.

As the organic material constituting the substrate, for example, polyethylene terephthalate, polycarbonate,
Polyimide, polymethyl methacrylate, polystyrene,
Examples include polyethylene, polyvinyl chloride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyarylate, polysulfone, cellulose, polyetheretherketone, and the like. Examples of the inorganic material forming the substrate include silicon, glass, and metal.

The surfaces of these substrates can be treated, for example, as electrodes. As a material constituting the electrode, for example, indium tin oxide (IT
O), indium oxide, zinc oxide, tin oxide, sodium, potassium, magnesium, aluminum, gold, silver,
How, indium, and the like.

An alignment treatment may be applied to the surface of the substrate in order to align the polymerizable rod-shaped liquid crystal in a certain direction. Examples of the orientation method include a method of rubbing the substrate surface with a cloth or the like, a method of obliquely depositing SiO ₂ on the substrate surface, and the like. When a substrate that has not been subjected to an alignment treatment is used, a rod-shaped liquid crystal having polymerizability can be aligned using an electric field or a magnetic field. These alignment means may be used alone or in combination.

When a proper orientation cannot be obtained by rubbing the substrate with a cloth or the like, an organic thin film such as a polyimide thin film or a polyvinyl alcohol thin film is formed on the substrate surface according to a known method, and this is rubbed with a cloth or the like. May be. Further, a polyimide thin film which gives a pretilt angle as used in a normal twisted nematic (TN) or super twisted nematic (STN) cell may be used. Further, a photo-alignment method can be used instead of the rubbing treatment.

When the orientation state is controlled by an electric field, a substrate having an electrode layer can be used. In this case, it is preferable to form an organic thin film such as the above-mentioned polyimide thin film on the electrode.

As for the polymerization method, since rapid polymerization is desirable, a method of photopolymerizing by irradiating the above-mentioned substrate with an energy ray such as an ultraviolet ray or an electron beam is preferable. The temperature at this time must be a temperature at which the liquid crystal state of the polymerizable liquid crystal composition containing the rod-shaped liquid crystal having polymerizability used in the present invention is maintained, but in order to avoid thermal polymerization, it is as close to room temperature as possible. It is preferred to polymerize at a temperature.

The charge transporting material of the present invention comprises an organic light emitting device,
Electronic devices such as optical sensors, electrophotographic photosensitive members, and image recording devices can be manufactured. When used in an organic light emitting device, the charge transporting material of the present invention to which a light emitting material is added as necessary is used as a light emitting layer as two light emitting electrodes (at least one of which is an IT
(A transparent electrode such as O). In the case of a multilayer organic light-emitting device, the charge transport material of the present invention can be used as a hole transport layer, an electron transport layer, or a light-emitting layer. When used for optical sensors,
By sandwiching the charge transporting material of the present invention between two electrodes (at least one of which is transparent), a current change due to light irradiation can be detected. When used as an electrophotographic photosensitive member or an image recording element, it can be produced by laminating a charge generation layer and the charge transport layer of the present invention on a substrate or an electrode.

The charge generation layer constituting the electrophotographic photosensitive member or the image recording element is a vapor deposition layer of a charge generation material or a layer in which the charge generation material is dispersed in a binder resin.

Examples of the charge generating material include azo pigments such as sudan red and diamble, quinone pigments such as pyrenequinone and anthantrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and phthalocyanine pigments. Is mentioned.

Examples of the binder resin include, for example, polycarbonate resin, polyvinyl butyral, polystyrene,
Examples include polyvinyl acetate and acrylic resin.

The resin-dispersed type charge generation layer comprises the charge generation material together with 0.3 to 4 times the amount of a binder resin and a solvent,
A dispersion well dispersed by a method such as a homogenizer, an ultrasonic dispersion, a ball mill, a vibrating ball mill, a sand mill, an attritor, a roll mill, and a liquid collision type high-speed disperser can be formed by coating and drying. The thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably in the range of 0.1 to 2 μm.

[0062]

The present invention will be described in more detail with reference to the following examples. However, the invention is not limited to the scope of these examples.

(Embodiment 1) Equation (3)

[0064]

Embedded image

33 parts by weight of the compound represented by the formula (4)

[0066]

Embedded image

33 parts by weight of the compound represented by the formula (5)

[0068]

Embedded image

A polymerizable liquid crystal composition (A) was prepared by mixing 34 parts by weight of the compound represented by the formula (1). The obtained composition showed a smectic A phase at room temperature, a phase transition temperature from the smectic A phase to the nematic phase was 57 ° C, and a phase transition temperature from the nematic phase to the isotropic phase was 97 ° C.
Further, 1 part by weight of a photopolymerization initiator "Irgacure-651" (manufactured by Ciba Geigy) was mixed and dissolved in 99 parts by weight of the polymerizable liquid crystal composition to obtain a liquid crystal composition (B).

A paint obtained by dispersing 2 parts by weight of titanyl phthalocyanine in a resin solution obtained by dissolving 1 part by weight of a polyvinyl butyral resin in a mixed solvent consisting of 29 parts by weight of dichloromethane and 43 parts by weight of 1,1,2-trichloroethane was applied to a resin having a thickness of 300 mm. 1mm thick with ITO electrode, 3m in size
0.3 μm thick after drying on a glass substrate of mx 3 mm
Then, the resultant was dried to form a charge generation layer. With the charge generation layer of the ITO substrate having the charge generation layer facing inside and a substrate having an ITO electrode on which another charge generation layer was not coated over a 9 μm spacer, the injection hole was removed. An adhesive was applied to the peripheral portion, and the cell was sealed by drying.

The liquid crystal composition (B) was injected into the cell thus prepared. While holding this sample in a magnetic field of 1.2 A / m, a 50 mW ultraviolet ray was irradiated for 1 minute to polymerize the liquid crystal polymer. Observation of the two samples between the polarizing films revealed that the polymerizable liquid crystal composition had a monodomain homogeneous alignment.

The hole mobility of this sample was measured at a temperature of 25 ° C.
Then, a voltage of 20 V is applied with the substrate side having the charge generation layer as a positive electrode, and a nitrogen laser-excited dye laser is applied.
A light pulse of 75 nm was incident from the substrate side, and measurement was performed by the time-of-flight method. As a result, a non-dispersive TOF waveform was obtained, and the hole mobility calculated ^therefrom was 3 × 10 ⁻⁵ cm ² / V · sec.

[0073]

The charge transport material of the present invention exhibits charge transport ability at room temperature and is stable without crystallization, so that it is suitable for use in electronic devices such as organic light emitting devices, electrophotographic photosensitive members, image forming devices, and optical sensors. Very useful as a material.

Claims (13)

[Claims] 1. A charge transport material comprising a polymer of a polymerizable liquid crystal composition containing a polymerizable rod-shaped liquid crystal. 2. The charge transport material according to claim 1, wherein the polymerizable liquid crystal composition containing a polymerizable rod-shaped liquid crystal exhibits a smectic phase. 3. The polymerizable liquid crystal composition containing a polymerizable rod-like liquid crystal shows a phase sequence of a smectic phase-nematic phase-isotropic liquid phase in order from a low temperature side to a high temperature side.
The charge transport material as described in the above. 4. A polymerizable liquid crystal composition containing a polymerizable rod-like liquid crystal, comprising a cyclic alcohol, phenol or aromatic hydroxy compound having a liquid crystal skeleton having at least two 6-membered rings in one molecule as a partial structure. 4. An acrylic or methacrylic ester containing a compound having one acryloyloxy group or methacryloyloxy group in one molecule.
3. The charge transport material according to item 1. 5. A polymerizable liquid crystal composition containing a polymerizable rod-like liquid crystal, comprising a cyclic alcohol, phenol or aromatic hydroxy compound having, as a partial structure, a liquid crystal skeleton having at least two 6-membered rings in one molecule. A compound which is an acrylate ester or a methacrylate ester and has one acryloyloxy group or methacryloyloxy group in one molecule is represented by the general formula (1): (Wherein, X represents a hydrogen atom or a methyl group, and the 6-membered rings A, B and C each independently represent And n represents an integer of 0 or 1, and p represents 1 to 4.
Wherein Y ¹ and Y ² are each independently a single bond, -CH ₂ CH _2- , -CH ₂ O-, -OCH _2- , -C
OO-, -OCO-, -C≡C-, -CH = CH-,-
CF = CF -, - (CH 2) 4 -, - CH 2 CH 2 CH 2 O
_{-, - OCH 2 CH 2 CH} 2 -, - CH 2 = CHCH 2 CH 2
— Or —CH ₂ CH ₂ CH ＝ CH—, Y ³ represents a single bond, —COO—, or —OCO—, and Z is a hydrogen atom, a halogen atom, a cyano group, or an alkyl group having 1 to 20 carbon atoms. , An alkoxy group, an alkenyl group or an alkenyloxy group. 5. The charge transport material according to claim 4, which is a polymerizable liquid crystal represented by the following formula: 6. The charge transport according to claim 1, wherein the polymer is a polymer obtained by polymerizing a polymerizable liquid crystal composition containing a polymerizable rod-like liquid crystal in a homogeneously aligned state. material. 7. The mobility of electrons or holes is 1 × 10 ⁻⁵ cm.
² / V · sec or more.
The charge transport material as described in the above. 8. The method for producing a charge transport material according to claim 1, wherein the polymerizable liquid crystal composition containing the polymerizable rod-shaped liquid crystal is polymerized by light irradiation or electron beam irradiation. 9. The method for producing a charge transporting material according to claim 8, wherein the polymerizable liquid crystal composition containing the polymerizable rod-shaped liquid crystal contains a photopolymerization initiator. 10. The method for producing a charge transport material according to claim 8, wherein a polymerizable liquid crystal composition containing a polymerizable rod-like liquid crystal is polymerized at a temperature showing a liquid crystal phase. 11. The method according to claim 10, wherein the liquid crystal phase is a smectic phase. 12. The charge transport material according to claim 8, wherein the polymerizable liquid crystal composition containing the polymerizable rod-like liquid crystal is polymerized after being oriented by a magnetic field. Method. 13. An electronic device comprising the charge transport material according to claim 1 as a component.