JP2917426B2 - Photoconductor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photoconductor containing an oxazole-based or oxadiazole-based laser dye as an additive.

2. Description of the Related Art Generally, in electrophotography, an electrostatic latent image is formed by charging and exposing a photosensitive layer surface of a photoreceptor, and then developing with a developer to visualize the image. A direct method of fixing a photoreceptor to obtain a copy image, a powder image transfer method of transferring a visible image on a photoreceptor onto a transfer material such as paper, and fixing the transferred image to obtain a copy image, or a photosensitive method. 2. Related Art A latent image transfer method of transferring an electrostatic latent image on a body onto transfer paper, and developing and fixing the electrostatic latent image on the transfer paper is known.

As a material constituting a photosensitive layer of a photoreceptor used in this type of electrophotography, conventionally, selenium, gadmium sulfide,
Inorganic photoconductive materials such as zinc oxide are known.

These photoconductive materials have a number of advantages, such as less charge dissipation in a dark place, or the ability to quickly dissipate charge by light irradiation, but have various disadvantages. For example, in the case of a selenium-based photoconductor, manufacturing conditions are difficult, the manufacturing cost is high, and the selenium-based photoconductor is susceptible to heat and mechanical shock.
Cadmium sulfide photoreceptors and zinc oxide photoreceptors do not provide stable sensitivity in humid environments, and dyes added as sensitizers cause charge deterioration due to corona charging and photobleaching due to exposure, resulting in long-term However, there is a disadvantage that stable characteristics cannot be provided over a wide range.

On the other hand, various organic photoconductive polymers such as polyvinyl carbazole have been proposed, but these polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film-forming properties and lightness. However, they are still inferior to inorganic photoconductive materials in terms of sufficient sensitivity, durability and stability due to environmental changes.

The low molecular weight organic photoconductive compound is preferable in that the physical properties of the film or the electrophotographic properties can be produced by selecting the type and composition ratio of the binder used in combination. Since it is used together with the material, high compatibility with the binder is required.

A photoreceptor in which these high molecular weight and low molecular weight organic photoconductive compounds are dispersed in a binder resin has drawbacks such as a large residual potential due to many carrier traps and low sensitivity. Therefore, it has been proposed to solve the above-mentioned drawbacks by blending a charge transport material with a photoconductive compound.

Also, a function-separated type photoreceptor has been proposed in which the charge generation function and the charge transport function of the photoconductive function are shared by different substances. In such a function-separated type photoreceptor, many organic compounds are mentioned as the charge transporting material used for the charge transporting layer, but there are various problems in practice. For example, 2,5-bis (P-diethylaminophenyl) 1,3,4-oxadiazole described in U.S. Pat. No. 3,189,447 has low compatibility with a binder and tends to precipitate crystals. U.S. Patent 3,820,989
The diarylalkane derivative described in Japanese Patent Application Laid-Open Publication No. H08-27139 has good compatibility with a binder, but changes in sensitivity when used repeatedly. In addition, the hydrazone compound described in JP-A-54-59143 has a relatively good residual potential characteristic, but has a drawback of poor charging ability and repetition characteristics.

Thus, in order to satisfy the practicality as a photoreceptor, it is necessary to be excellent in repetition characteristics, light fatigue characteristics, their durability, etc. in addition to sensitivity and charging ability.

However, the organic photoreceptor generally has a problem in that the initial surface potential or light attenuation characteristics are not constant due to repeated use, and there is a problem that light fatigue is severe and durability is poor.

Techniques for improving the photosensitivity and durability of the photoreceptor include, for example, JP-A-60-191264 and JP-A-59-12.
No. 3845 is known.

JP-A-60-191264 discloses a technique capable of achieving excellent photosensitivity and repetition characteristics of initial surface potential by including a hydrazone compound in a photosensitive layer. This technique discloses that addition of an acridine dye, a thiazine dye or an oxazine dye is effective for further sensitizing photosensitivity. However, the photoreceptor still has a disadvantage that when repeatedly used, electrophotographic characteristics such as surface potential and residual potential are not stable.

JP-A-59-123845 discloses an electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated by adding an electron donating substance such as phenazine and triazole to the charge generation layer. Discloses a technique for improving the injection efficiency of carriers generated in the charge generation layer into the charge transport layer and improving the photosensitivity characteristics. It is not intended to improve.

Japanese Patent Application Laid-Open No. 62-249167 discloses that a thioxanthone-based compound is added to a photosensitive layer to stabilize repetition characteristics, and Japanese Patent Application Laid-Open No. 62-262053 discloses that a thiuram monosulfide-based compound is added to a photosensitive layer. Stabilizing the repetition properties by adding a compound; and
No. 6 discloses stabilizing the repetition characteristics by adding a triphenylmethane dye.

However, in any of the above-mentioned photoreceptors, further improvement in the photoreceptor characteristics such as repetition characteristics and durability is desired, and the type of the additive differs from the additive disclosed in the present application.

Problems to be Solved by the Invention The present invention has been made in view of the above circumstances, and has initial characteristics (sensitivity, surface potential, etc.) even when used repeatedly.
It is an object of the present invention to provide a photoreceptor which can maintain a stable image quality and can form a stable copy image with little deterioration.

This object is achieved by adding an oxazole-based or oxadiazole-based laser dye to the photosensitive layer.

Means for Solving the Problems That is, the present invention provides a photosensitive member having a photosensitive layer containing a charge transport material on a conductive support, wherein the photosensitive layer is a single layer or a laminated structure of a charge transport layer and a charge generation layer. And
An oxadiazole-based laser dye represented by the following general formula [I] or an oxazole-based laser dye represented by the following general formula [II] in a layer containing a charge transport material among layers constituting a photosensitive layer; [Wherein, Ar ₁ represents a phenyl group, a naphthyl group, a biphenyl group, an alkylphenyl group or a halogenated phenyl group; Ar ₂ represents a phenyl group, a naphthyl group or a biphenyl group; n represents a number of 1 or 2 . ] Wherein Ar ₃ represents a phenyl group, a naphthyl group, a biphenyl group, an alkylphenyl group or a halogenated phenyl group; Ar ₄ represents a phenyl group, a naphthyl group or a biphenyl group; R represents a hydrogen atom, a methyl group or a halogen Represents an atom; n represents a number of 1 or 2. ] It relates to the photoreceptor containing.

As described above, by adding an oxazole-based or oxadiazole-based laser dye to a photosensitive layer containing a charge-transporting substance, it is possible to obtain a high-performance photoreceptor with little change in initial characteristics even when used repeatedly. .

In the present invention, the oxazole-based or oxadiazole-based laser dye is various derivatives having oxazole or oxadiazole as a basic skeleton, and means those used as a laser dye. In the present invention, a dye having a relatively high quantum yield of fluorescence is required to be a laser dye. More specifically, in the case that from the singlet excited state S ₁ small transition probability to the triplet excited state T _1, although such as by dissolving in a suitable solvent is required, which is particularly excited by the laser beam, the emission intensity of the fluorescent Means something strong. Here, the laser light refers to, for example, a gas laser, a group laser, a flash lamp, or the like.

Examples of the compound that can be used in the present invention include the following general formula [I]: [Wherein, Ar ₁ represents a phenyl group, a naphthyl group, a biphenyl group, an alkylphenyl group or a halogenated phenyl group; Ar ₂ represents a phenyl group, a naphthyl group or a biphenyl group; n represents a number of 1 or 2 .

Or an oxadiazole compound represented by the following general formula [II]: Wherein Ar ₃ represents a phenyl group, a naphthyl group, a biphenyl group, an alkylphenyl group or a halogenated phenyl group; Ar ₄ represents a phenyl group, a naphthyl group or a biphenyl group; R represents a hydrogen atom, a methyl group or a halogen Represents an atom; n represents a number of 1 or 2.

Examples thereof include, but are not particularly limited to, oxazole-based compounds represented by the formula: Those used as dyes can also be used.

Specifically, compounds represented by the following structural formulas can be exemplified.

The photoreceptor of the present invention has a photosensitive layer containing one or more oxazole-based or oxadiazole-based laser dyes.

Although various forms of photoreceptors are known, an oxazole-based or oxadiazole-based laser dye may be contained in the photosensitive layer of any of the photoreceptors.

For example, a single-layer photoreceptor having a charge generating material and a photosensitive layer formed by dispersing a charge generating material in a resin binder on a support, or a charge generating layer having a charge generating material as a main component is provided on a support. And a so-called laminated photoreceptor provided with a charge transport layer thereon.

In order to produce a single-layer photoreceptor, fine particles of a charge generation material are dispersed in a resin solution and a solution in which a charge transport material and a resin are dissolved together with an oxazole-based or oxadiazole-based laser dye, and the resultant is dispersed in a conductive material. What is necessary is just to apply | coat and dry on a sexual support.

At this time, the charge transporting material is generally used in an amount of 0.01 to 2 parts by weight based on 1 part by weight of the binder resin, and the amount of the oxazole-based or oxazole-based laser dye added is 0.1 to 40 parts by weight based on the charge transporting material. % By weight, preferably 0.5
-30% by weight, more preferably 1-20% by weight. If the content is more than 40% by weight, the sensitivity deteriorates, and the residual potential increases. If the amount is less than 0.1% by weight, the effect of the present invention cannot be sufficiently obtained.

The thickness of the photosensitive layer is 3 to 30 μm, preferably 5 to 20 μm. If the amount of the charge generating material used is too small, the sensitivity is poor, and if it is too large, the chargeability is deteriorated, the mechanical strength of the photosensitive layer is reduced, and the proportion in the photosensitive layer is 1 part by weight of the resin. 0.01 to 3 parts by weight, preferably 0.2 to 2 parts by weight
The range of parts by weight is good.

To produce a laminated photoreceptor, a charge generation material is vacuum-deposited on a conductive support, or dissolved in a solvent such as an amine and applied, or a pigment is applied to a suitable solvent or a binder if necessary. It is obtained by applying and drying a coating solution prepared by dispersing in a solution in which a resin is dissolved, and then applying and drying a solution containing an oxazole-based or oxazole-based laser dye, a charge transport material and a binder.

When the charge generation layer is formed of a binder resin dispersion type, the charge generation material is used in an amount of 0.1 to 5 parts by weight with respect to 1 part by weight of the binder resin for the same reason as the case of forming the single layer type photosensitive layer.

In the charge transport layer, the ratio of the charge transport material in the layer is from 0.2 to 2 parts by weight, preferably from 0.3 to 1.3 parts by weight, based on 1 part by weight of the binder resin, and the addition of an oxazole-based or oxazole-based laser dye. The amount is 0.1 to 40% by weight, preferably 0.5 to 30% by weight, based on the charge transporting material, for the same reason as described for the single-layer type photosensitive layer.
More preferably, it is 1 to 20% by weight.

The thickness of the charge generation layer is 4 μm or less, preferably 2 μm or less, and the thickness of the charge transport layer is 3 to 30 μm, preferably 5 to 20 μm.

In the present invention, as the electrically insulating binder resin used for forming the photosensitive layer, a thermoplastic resin or a thermosetting resin, a photocurable resin, a photoconductive resin, or the like, which is known per se, is an electrically insulating resin. An adhesive can be used.

Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins,
Thermoplastic resins such as acrylic resin, ethylene-vinyl acetate resin, ion-crosslinked olefin copolymer (ionomer), styrene-butadiene block copolymer, polycarbonate, vinyl chloride-vinyl acetate copolymer, cellulose ester, polyimide, and styrene resin ; Epoxy resin, urethane resin, silicone resin, phenol resin,
Thermosetting resins such as melamine resins, xylene resins, alkyd resins, and thermosetting acrylic resins; photocurable resins; photoconductive resins such as polyvinylcarbazole, polyvinylpyrene, polyvinylanthracene, and polyvinylpyrrole.

These can be used alone or in combination.

These electrically insulative resins were measured alone to be 1 × 10 ¹² Ω
-It is desirable to have a volume resistance of not less than cm.

Examples of the charge generation material used for forming the photosensitive layer include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, cyanine dyes, styryl dyes, pyrylium dyes, and azo pigments. , Organic substances such as quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indathrone pigments, squarium salt pigments, azulene pigments, phthalocyanine pigments, and selenium, Selenium alloys such as selenium / tellurium, selenium / arsenic, cadmium sulfide, cadmium selenide, zinc oxide,
An inorganic substance such as amorphous silicon can be used. In addition, any material that absorbs light and generates charge carriers at an extremely high probability can be used.

Examples of those applicable to vacuum deposition include phthalocyanines such as metal-free phthalocyanine, titanyl phthalocyanine, and aluminum chlorophthalocyanine.

Hydrazone compounds, pyrazoline compounds, styryl compounds, triphenylmethane compounds, carbazole compounds, stilbene compounds, enamine compounds, oxazole compounds, triphenylamine compounds, tetraphenylbenzidine compounds, azine compounds as charge transport materials used for forming the photosensitive layer Various ones can be used, such as carbazole, N-ethylcarbazole, N
-Vinylcarbazole, N-phenylcarbazole, tetracene, chrysene, pyrene, perylene, 2-phenylnaphthalene, azapyrene, 2,3-benzochrysene, 3,4-
Benzopyrene, fluorene, 1,2-benzofluorene,
4- (2-fluorenylazo) resorcinol, 2-p
-Anisoleaminofluorene, p-diethylaminoazobenzene, cadion, N, N-dimethyl-p-phenylazoaniline, p- (dimethylamino) stilbene, 9
-(4-diethylaminostyryl) anthracene, 2,5
-Bis (4-diethylaminophenyl) -1,3,5-oxadiazole, 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3-phenyl- 5-pyrazolone, 2- (p-diethylaminostyryl) -6-diethylaminobenzoxazole, 2- (p-diethylaminostyryl) -6-diethylaminobenzthiazole,
Bis (4-diethylamino-2-methylphenyl) phenylmethane, 1,1-bis (4-N, N-diethylamino-2
-Ethylphenyl) heptane, N, N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, N,
N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, 1,1,2,2, tetrakis- (4-N, N-
Diethylamino-2-ethylphenyl) ethane, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diphenylaminobenzaldehyde-N, N
-Diphenylhydrazone, N-ethylcarbazole-N
-Methyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-3
-Methylbenzthiazolinone-2-hydrazone, 2-methyl-4-N, N-diphenylamino-β-phenylstilbene, α-phenyl-4-N, N-diphenylaminostilbene, 1,1-bis- ( (p-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene and the like.

These transport substances are used alone or in combination of two or more.

The photoreceptor of the present invention further comprises a plasticizer such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutylphthalate, O-terphenyl, chloranil, tetracyanoethylene, 2,4,7 together with a binder resin.
Electron-withdrawing sensitizers such as trinitrofluorenone, 5,6-dicyanobenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5-dinitrobenzoic acid,
Sensitizers such as methyl violet, rhodamine B, cyanine dyes, pyrylium salts, and thiapyrylium salts may be used.

Further, an antioxidant, an ultraviolet absorber, a dispersing aid, an anti-settling agent, and the like may be appropriately used.

As the conductive support used in the photoreceptor of the present invention,
Copper or aluminum, silver, iron, zinc, nickel or other metal or alloy foils or plates in the form of sheets or drums are used, or these metals are vacuum deposited or electroless plated on plastic films or the like. Or a material in which a layer of a conductive compound such as a conductive polymer, indium oxide or tin oxide is provided on a support such as paper or a plastic film by coating or vapor deposition.

In addition, any of the photoreceptors obtained as described above may be provided with an adhesive layer or a barrier layer and a surface protective layer as necessary.

As a material used for the intermediate layer, polyimide, polyamide, nitrocellulose, polyvinyl butyral, a polymer such as polyvinyl alcohol as it is, or a dispersion of a low-resistance compound such as tin oxide or indium oxide, aluminum oxide, zinc oxide, A deposited film of silicon oxide or the like is suitable.

 The thickness of the intermediate layer is desirably 1 μm or less.

As the material used for the surface protective layer, a polymer such as an acrylic resin, a polyaryl resin, a polycarbonate resin, or a urethane resin as it is, or a material in which a low-resistance compound such as tin oxide or indium oxide is dispersed is suitable.

An organic plasma polymerized film can also be used. The organic plasma polymerized film is appropriately oxygen, nitrogen, halogen,
It may contain atoms of the third and fifth groups of the periodic table.

 The thickness of the surface protective layer is desirably 5 μm or less.

The photoreceptor of the present invention can be used for a photoreceptor for a laser printer.

Example 1 Bisazo compound represented by the following chemical formula [A]: One part by weight (hereinafter, parts by weight are referred to as "parts") and 1 part of a polyester resin (V-200: manufactured by Toyobo Co., Ltd.) were dispersed together with 90 parts of cyclohexanone by a sand glider. The obtained dispersion of the bisazo compound is placed on an aluminum drum,
Dry film thickness dried after application as a 0.2 g / m ^2,
A charge generation layer was formed.

A butadiene chemical compound represented by the following formula [B] is formed on the charge generation layer thus obtained: 10 parts and polycarbonate resin (Panlite K-130
0; Teijin Chemicals Co., Ltd.) 10 parts was dissolved in tetrahydrofuran 80 parts, and a coating solution containing 0.5 part of compound [2] was applied by dipping and dried to form a charge transport layer having a thickness of about 20 μm. Formed. In this way, an electrophotographic photoreceptor having two photosensitive layers was obtained.

Examples 2 to 4 In Example 1, the amount of compound [2] added was 0.25 part,
A photoconductor was prepared by the same way as that of Example 1 except that 0.75 parts and 1 part were used.

Comparative Example 1 A photoconductor was prepared by the same way as that of Example 1 except that Compound [2] was not added.

Comparative Example 2 In Example 1, instead of compound [2], 2,5-
A photoconductor was prepared by the same way as that of Example 1 except that 0.5 part of di-ter-butyl-p-cresol was added.

Comparative Example 3 In Example 1, instead of compound [2], tri-
A photoconductor was prepared by the same way as that of Example 1 except that 0.5 part of norylphenylphenyl-phosphite was added.

Comparative Example 4 A photoconductor was prepared by the same way as that of Example 1 except that 0.5 part of phenazine was added instead of compound [2].

Comparative Example 5 Example 2 was repeated, except that compound [2] was replaced by 2-
A photoconductor was prepared by the same way as that of Example 1 except that 0.5 part of (2'-hydroxy-5'-methylphenyl) benzotriazole was added.

Example 5 Bisazo compound represented by the following chemical formula [C]: One part of butyral resin (BH-3: manufactured by Sekisui Chemical Co., Ltd.) was dispersed in a sand mill together with 90 parts of cyclohexanone. The obtained dispersion liquid of the bisazo compound was applied on an aluminum drum so that the film thickness after application was 0.2 g / m ^2, and then dried.

A distyryl compound represented by the following chemical formula [D] is formed on the charge generation layer thus obtained: 10 parts, 10 parts of a polycarbonate resin (PC-Z: manufactured by Mitsubishi Gas Chemical Co., Ltd.) were dissolved in 80 parts of tetrahydrofuran, and a coating solution containing 0.3 part of the compound [3] was applied by a dipping method. A charge transport layer was formed.

Thus, a photoreceptor having a two-layered photosensitive layer was obtained.

Comparative Example 6 A photoconductor was prepared by the same way as that of Example 5 except that Compound [3] was not added.

Comparative Example 7 A photoconductor was prepared by the same way as that of Example 5 except that, instead of compound [3], 0.3 parts of surfactant polyoxyethylene nonylphenyl ether was added.

Example 6 4.5 parts of α-type titanyl phthalocyanine, 4.5 parts of butyral resin (BX-1: manufactured by Sekisui Chemical Co., Ltd.) and 0.45 of compound [6]
Parts were dispersed in a sand mill together with 500 parts of dichloroethane. The obtained dispersion was applied on an aluminum drum such that the coating liquid had a thickness of 0.2 g / m ^2, and then dried.

On the charge generation layer thus obtained, 10 parts of a butadiene compound represented by the above formula [B] and a hydrazone compound represented by the above formula [E]: 40 parts and polyarylate (U-100: manufactured by Unitika) 50
A solution in which 500 parts of tetrahydrofuran was dissolved was applied and dried to form a charge transport layer having a thickness of about 15 μm.

Thus, a photoreceptor having a two-layered photosensitive layer was obtained.

Examples 7 to 10 In Example 6, the amount of compound [6] was 0.23 parts,
A photoconductor was prepared by the same way as that of Example 6 except that 68 parts, 0.9 parts and 1.35 parts were used.

Comparative Example 8 A photoconductor was prepared by the same way as that of Example 6 except that compound [6] was not added.

Comparative Example 9 A photoconductor was prepared by the same way as that of Example 6 except that 0.45 part of trinitrofluorenone was added instead of compound [6].

Comparative Example 10 In Comparative Example 6, 1H-1,2,4 was used instead of compound [6].
A photoconductor was prepared by the same way as that of Example 6 except that 0.45 part of triazole was added.

Evaluation The photoreceptor obtained in this way was converted to a commercially available electrophotographic copying machine (EP
−50 (50Φ: manufactured by Minolta Camera Co.), and corona charged at −6 KV, and the initial surface potential V ₀ (V) and the initial potential
The amount of exposure E _1/2 (lux · sec) required to obtain 2 and the decay rate DDR ₁ (%) of the initial potential when left in the dark for 1 second were measured. Table 1 shows the results.

Further, the photoreceptor was attached to a photoreceptor tester (FIG. 1) having the same configuration as the copying machine, and the electrophotographic characteristics were measured.

That is, the photoconductors obtained in Examples and Comparative Examples were mounted on the photoconductor drum (1), charged to −500 V by the charger (2), and then the initial surface potential (V ₀ ) of the photoconductor 0.3 seconds later, After charging, the surface potential (V _i ) after exposure to white light (3) from a halogen lamp and the residual electric field (V _r ) after exposure and removal of electricity by a light eraser (5) are measured by a probe (4). After each measurement, and after repeating the above process 5000 times
To measure the V _0, V _i and V _r, examined the repetition characteristics.

 The results are shown in Table 2.

Effects of the Invention The photoreceptor of the present invention can improve sensitivity and repetition stability without lowering charge retention ability, and can obtain high image stability.

[Brief description of the drawings]

 FIG. 1 is a diagram showing a schematic configuration of a photoconductor tester.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kimiyuki Ito 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Yuki Shimada Chuo-ku, Osaka-shi, Osaka 2-3-13 Azuchicho Osaka Kokusai Building Minolta Camera Co., Ltd. (56) References JP-A-58-120257 (JP, A) JP-A-58-9152 (JP, A) JP-A-63-159855 ( JP, A) JP-A-60-37561 (JP, A) JP-A-58-54344 (JP, A) JP-A-54-5433 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) G03G 5/05 104

Claims (2)

(57) [Claims] 1. A photosensitive member having a photosensitive layer containing a charge transport material on a conductive support, wherein the photosensitive layer has a single layer structure or a laminated structure of a charge transport layer and a charge generation layer. An oxadiazole-based laser dye represented by the following general formula [I] or an oxazole-based laser dye represented by the following general formula [II] in a layer containing a charge-transporting substance; [Wherein, Ar ₁ represents a phenyl group, a naphthyl group, a biphenyl group, an alkylphenyl group or a halogenated phenyl group; Ar ₂ represents a phenyl group, a naphthyl group or a biphenyl group; n represents a number of 1 or 2 . ] Wherein Ar ₃ represents a phenyl group, a naphthyl group, a biphenyl group, an alkylphenyl group or a halogenated phenyl group; Ar ₄ represents a phenyl group, a naphthyl group or a biphenyl group; R represents a hydrogen atom, a methyl group or a halogen Represents an atom; n represents a number of 1 or 2. ] A photoreceptor containing: 2. The amount of the oxadiazole-based laser dye or the oxazole-based laser dye according to claim 1 is:
A photoreceptor which is 0.1 to 40% by weight based on the charge transport material.