JPH0331258B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a photoreceptor, and more particularly to a novel photoreceptor having a photosensitive layer containing a specific azo compound. [Prior Art] Conventionally, inorganic photoreceptors having a photosensitive layer mainly composed of an inorganic photoconductive compound such as selenium, zinc oxide, cadmium sulfide, silicon, etc. have been widely used as photoreceptors. However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, etc. For example, when selenium crystallizes, its properties as a photoreceptor deteriorate, making it difficult to manufacture, and it also crystallizes due to heat, fingerprints, etc.
The performance as a photoreceptor deteriorates. In addition, cadmium sulfide has problems in moisture resistance and durability, and zinc oxide has problems in durability, etc. In order to overcome these drawbacks of inorganic photoreceptors, research and development have been actively conducted in recent years on organic photoreceptors having photosensitive layers containing various organic photoconductive compounds as main components. For example, Japanese Patent Publication No. 50-10496 describes an organic photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2,4,7-trinitro-9-fluorenone. However, this photoreceptor is not necessarily satisfactory in sensitivity and durability. In order to improve these drawbacks, attempts have been made to develop organic photoreceptors with higher performance by assigning the carrier generation function and the carrier transport function to different substances. Many studies have been conducted on such so-called function-separated type photoreceptors because each material can be selected from a wide range and a photoreceptor having arbitrary performance can be produced relatively easily. Many compounds have been proposed as carrier generating substances for such functionally separated photoreceptors. Examples of using inorganic compounds as carrier generating substances include, for example, Japanese Patent Publication No. 43-16198.
There is an amorphous selenium described in the issue, which is used in combination with an organic photoconductive compound, but the carrier generation layer made of amorphous selenium crystallizes due to heat, deteriorating its properties as a photoreceptor. This shortcoming has not been improved. Many photoreceptors have also been proposed that use organic dyes or organic pigments as carrier generating substances. For example, as a photoreceptor containing a bisazo compound in the photosensitive layer,
No. 56-46237, No. 58-194035, etc. are already known. However, these bisazo compounds or trisazo compounds are not necessarily satisfactory in terms of sensitivity, residual potential, or stability during repeated use, and the selection range of carrier transport materials is also limited. It does not fully satisfy the wide range of demands of photographic processes. Furthermore, in recent years, Ar lasers and He lasers have been used as light sources for photoreceptors.
-Gas lasers such as Ne lasers and semiconductor lasers are beginning to be used. A characteristic of these lasers is that they can be turned on and off in a time-series manner, making them particularly promising light sources for copying machines with image processing functions, including intelligent copying machines, and printers for computer output. Among these, semiconductor lasers are attracting attention because their nature does not require electrical signal/optical signal conversion elements such as acousto-optic elements, and they can be made smaller and lighter. However, this semiconductor laser has a low output power compared to a gas laser, and the oscillation wavelength is also long (approximately
780 nm or more), the spectral sensitivity of conventional photoreceptors is too high on the short wavelength side, and as it is, it is impossible to use them as photoreceptors using semiconductor lasers as light sources. [Object of the Invention] An object of the present invention is to provide a photoreceptor containing a specific azo compound that is stable against heat and light and has excellent carrier generation ability. Another object of the present invention is to provide a photoreceptor with high sensitivity, low residual potential, and excellent durability whose characteristics do not change even after repeated use. Still another object of the present invention is to provide a photoreceptor containing an azo compound that can effectively act as a carrier generating material even in combination with a wide variety of carrier transport materials. Still another object of the present invention is to provide a photoreceptor having sufficient practical sensitivity even to long wavelength light sources such as semiconductor lasers. [Structure of the Invention] As a result of intensive research to achieve the above object, the present inventors discovered that an azo compound represented by the following general formula [ ] can act as an active ingredient of a photoreceptor, and the present invention This is the completed version. General formula [] In the formula, Y ₁ and Y ₂ are respectively an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group,
or a group selected from hydroxyl groups, l is an integer of 0 or 1, m and n are integers of 0 to 3 (however, m and n are not both 0), A is

【formula】

【formula】

[Formula] or

[Formula], Q is a substituted or unsubstituted carbamoyl group (

[Formula]), substituted or unsubstituted sulfamoy group (

[Formula]), R ₄ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms.
Unsubstituted aralkyl group, substituted or unsubstituted phenyl group, R ₅ is a hydrogen atom, substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, substituted or unsubstituted aromatic carbocyclic group (for example, substituted or unsubstituted Substituted phenyl group, substituted or unsubstituted naphthyl group, substituted or unsubstituted anthryl group, etc.), or substituted or unsubstituted aromatic heterocyclic group (such as substituted or unsubstituted carbazolyl group, substituted or unsubstituted dibenzo group, etc.) (furyl group, etc.). Substituents for these groups include, for example, carbon atoms with 1
~4 substituted/unsubstituted alkyl groups (e.g. methyl group, ethyl group, isopropyl group, tertiary butyl group,
trifluoromethyl group, etc.), substituted/unsubstituted aralkyl groups (e.g., benzyl group, phenethyl group, etc.), halogen atoms (chlorine atom, bromine atom, fluorine atom, iodine atom), substituted/unsubstituted aralkyl groups with 1 to 4 carbon atoms Substituted alkoxy groups (e.g. methoxy, ethoxy, isopropoxy, tertiary butoxy, 2-chloroethoxy, etc.), hydroxy groups, substituted/unsubstituted aryloxy groups (e.g. p-chlorophenoxy, 1- naphthoxy group, etc.), acyloxy group (e.g., acetyloxy group, p-cyanobenzoyloxy group, etc.), carboxyl group, its ester group (e.g., ethoxycarbonyl group, m-bromophenoxycarbonyl group, etc.), carbamoyl group ( For example, aminocarbonyl group, tertiary butylaminocarbonyl group, anilinocarbonyl group, etc.), acyl group (e.g. acetyl group, o-nitrobenzoyl group, etc.), sulfo group, sulfamoyl group (e.g. aminosulfonyl group, tertiary butyl group, etc.) aminosulfonyl group, p-tolylaminosulfonyl group, etc.),
Preferred examples include amino group, acylamino group (e.g., acetylamino group, benzoylamino group, etc.), sulfonamide group (e.g., methanesulfonamide group, p-toluenesulfonamide group, etc.), cyano group, nitro group, etc. is a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms (e.g., methyl group,
ethyl group, isopropyl group, butyl group, trifluoromethyl group, etc.), halogen atom (chlorine atom, bromine atom, fluorine atom, iodine atom), substituted or unsubstituted alkoxy group having 1 to 4 carbon atoms (e.g. methoxy group) , ethoxy group, tertiary butoxy group, 2-chloroethoxy group, etc.) cyano group, nitro group. Z is an atomic group necessary to form a substituted or unsubstituted aromatic carbocycle or a substituted or unsubstituted aromatic heterocycle, and specifically, for example, a substituted or unsubstituted benzene ring, a substituted or Represents an atomic group forming an unsubstituted naphthalene ring, a substituted or unsubstituted indole ring, a substituted or unsubstituted carbazole ring, etc. Examples of substituents for the atomic group forming these rings include a series of substituents such as those listed as substituents for R ₄ and R ₅ , but halogen atoms (chlorine, bromine, fluorine, etc.) are preferred. atom, iodine atom), a sulfo group, and a sulfamoyl group (for example, an aminosulfonyl group, a p-tolylaminosulfonyl group, etc.). R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group,
Substituted/unsubstituted amino group, carboxyl group, ester group thereof, substituted/unsubstituted carbamoyl group, cyano group, preferably hydrogen atom, carbon number 1-4
Substituted/unsubstituted alkyl groups (e.g., methyl group, ethyl group, isopropyl group, tertiary butyl group,
trifluoromethyl group, etc.) and cyano group. A' is a substituted or unsubstituted aryl group, preferably a substituted or unsubstituted phenyl group, and the substituents for these groups include a series of substituents such as those listed as substituents for R ₄ and R ₅ . Preferably, halogen atoms (chlorine atom, bromine atom, fluorine atom, iodine atom), substituted or unsubstituted alkyl groups having 1 to 4 carbon atoms (for example, methyl group, ethyl group, isopropyl group, tertiary butyl group, trifluoromethyl group, etc.), substituted or unsubstituted alkoxy groups having 1 to 4 carbon atoms (for example, methoxy group, ethoxy group, isopropoxy group, tertiary butoxy group, 2-chloroethoxy group). R ₂ and R ₃ represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, preferably a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms ( For example, methyl group,
ethyl group, isopropyl group, tertiary butyl group, trifluoromethyl group, etc.), substituted or unsubstituted phenyl group (for example, phenyl group, p-methoxyphenyl group, m-chlorophenyl group, etc.). Among the azo compounds represented by the general formula [] used in the present invention, particularly preferred compounds are l=1, that is, the compounds represented by the following general formula [], since they have excellent sensitivity even in the wavelength region of 780 nm or more. It has a structure that allows General formula [] In the formula, Y ₁ ′ and Y ₂ ′ are groups selected from alkyl groups or halogen atoms, and A, m, and n are general formulas []
is the same as Specific examples of the bisazo compound useful in the present invention represented by the general formula [] include those having the following structural formula, but the bisazo compound of the present invention is not limited thereby. . Something expressed by the general formula [] in the general formula []. General formula []

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

[Table] Those represented by the following general formula []. General formula []

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

【table】

〔Example〕

Example 1 2 g of exemplified compound B-(16) and polycarbonate resin "Panlite L-1250" (manufactured by Teijin Chemicals) 2
g was added to 110 ml of 1,2-dichloroethane and dispersed in a ball mill for 12 hours. This dispersion was applied onto a polyester film on which aluminum had been vapor-deposited so that the film thickness after drying would be 1 μm to form a carrier generation layer, and on top of this a carrier transport layer was applied as a 4,4′-methyl-4 ″-(4-chloro)-styryl-triphenylamine (Structural formula K-(1) below)
6g of polycarbonate resin “Panlite L-
1250" dissolved in 110 ml of 1,2-dichloroethane was coated to form a carrier transport layer so as to have a dry film thickness of 15 .mu.m, thereby producing the photoreceptor of the present invention. The photoreceptor obtained as described above was subjected to the following characteristic evaluation using an electrostatic paper tester model SP-428 manufactured by Kawaguchi Electric Seisakusho Co., Ltd. After charging with a charging voltage of -6KV for 5 seconds, leave in the dark for 5 seconds, then irradiate with halogen lamp light so that the illuminance on the photoreceptor surface is 35 lux, and calculate the amount of exposure required to attenuate the surface potential by half. (Half-reduced exposure amount) E1/2 was determined. or
The surface potential (residual potential) V _R after exposure with an exposure amount of 30 lux·sec was determined. Furthermore, similar measurements were repeated 100 times. The results were as shown in Table 1.

[Table] Comparative Example 1 The following bisazo compound G was used as a carrier generating substance.
A comparative photoreceptor was prepared in the same manner as in Example 1 except that -(1) was used. When this comparative photoreceptor was measured in the same manner as in Example 1, the results shown in Table 2 were obtained.

[Table] As is clear from the above results, the photoreceptor of the present invention was extremely superior in sensitivity, residual potential, and repeated stability compared to the comparative photoreceptor. Examples 2 to 4 Exemplary compounds B-(8), -(9), as carrier-generating substances
and B-(10), and 6-methyl-1-(1-phenyl-4-
carbazolyl) methylidene amino-1,2,3,
4-tetrahydroquinoline (compound K-(2) below),
1-(1-phenyl-4-carbazolyl)methylideneamino-1,2,3,4-tetrahydroquinoline (compound K-(3) below) and 4,4'-dimethyl-4''-(4-methyl) A photoreceptor of the present invention was prepared using styryl-triphenylamine (compound K-(4) below) in the same manner as in Example 1, and the same measurements were performed. The results are shown in Table 3. Obtained.

[Table] Example 5 A vinyl chloride-vinyl acetate-maleic anhydride copolymer "Eslec MP-10" (manufactured by Sekisui Chemical Co., Ltd.) was placed on a conductive support consisting of a polyester film laminated with aluminum foil. thickness
A 0.05 μm intermediate layer is provided, and exemplified compound B is placed on top of the intermediate layer.
2 g of -(15) was mixed with 110 ml of 1,2-dichloroethane and dispersed in a ball mill for 24 hours. The dispersion was applied to a dry film thickness of 0.5 μm to form a carrier generation layer. On this carrier generation layer, a solution of 6 g of 4-methyl-4'-styryl-triphenylamine and 10 g of methacrylic resin "Acrypet" (manufactured by Mitsubishi Rayon Co., Ltd.) dissolved in 70 ml of 1,2-dichloroethane was added after drying. A carrier transport layer was formed by coating the film to a thickness of 10 μm, thereby producing a photoreceptor of the present invention. When the same measurements as in Example 1 were carried out on this photoreceptor, the results of the first measurement were E1/2=2.3lux·sec and V _R =0V. Example 6 On the conductive support provided with the intermediate layer used in Example 5, a 1% ethylenediamine solution of Exemplary Compound B-(39) was applied to a dry film thickness of 0.3 μm, and a carrier was applied. A generation layer was formed. Then, 1-(1-ethyl-4-carbazolyl)methylidene (compound K-(5) below) 6 g and 10 g of polyester resin "Vylon 200" (manufactured by Toyobo Co., Ltd.) were dissolved in 70 ml of 1,2-dichloroethane, and this solution was applied to a dry film thickness of 12 μm to form a carrier transport layer. , a photoreceptor of the present invention was prepared. The same measurements as in Example 1 were performed on this photoreceptor, and the results shown in Table 4 were obtained. Comparative Example 2 A comparative photoreceptor was prepared in the same manner as in Example 6 except that exemplified compound B-(39) was replaced with bisazo compound G-(2) represented by the following structural formula. The same measurements as in Example 1 were performed on this photoreceptor, and the results are shown in Table 4.

[Table] Example 7 A carrier generation layer was formed in the same manner as in Example 5 except that Exemplified Compound B-(15) was replaced with Exemplified Compound B-(34). On top of this, 4-methoxy-
6 g of 4'-styryl-triphenylamine and 10 g of polycarbonate "Panlite L-1250" (manufactured by Teijin Kasei) were dissolved in 70 ml of 1,2-dichloroethane so that the film thickness after drying was 10 μm. A carrier transport layer was formed by coating to produce a photoreceptor of the present invention. When this photoreceptor was measured in the same manner as in Example 1, it was found that E1/2 = 2.2 lux·sec and V _R = 0V. Example 8 An intermediate layer with a thickness of 0.05 μm made of vinyl chloride-vinyl acetate-maleic anhydride copolymer “Eslec MP-10” (manufactured by Sekisui Chemical Co., Ltd.) was provided on the surface of an aluminum drum with a diameter of 100 mm, and then Add 4 g of Exemplified Compound B-(43) to 400 ml of 1,2-dichloroethane.
A dispersion liquid was mixed with the following and dispersed for 24 hours using a ball mill dispersion machine, and the dispersion liquid was applied so that the film thickness after drying was 0.6 μm to form a carrier generation layer. Furthermore, on top of this, 3-(p-methoxystyryl)-
30 g of 9-(p-methoxyphenyl)carbazole (compound K-(6) below) and 50 g of polycarbonate resin "Iupilon S-1000" (manufactured by Mitsubishi Gas Chemical Co., Ltd.)
and 1,2-dichloroethane A drum-shaped photoreceptor was prepared by dissolving the solution in 400 ml and applying it to a dry film thickness of 13 μm to form a carrier transport layer. The photoconductor created in this way was installed in a modified electrophotographic copying machine "U-Bix1600MR" (manufactured by Konica Corporation), and when the image was copied, the resulting copy showed high contrast, was faithful to the original image, and was clear. I got it.
Also, this did not change even after repeating this 10,000 times. Comparative Example 3 A drum-shaped comparative sample was prepared in the same manner as in Example 8, except that the exemplified compound B-(43) in Example 8 was replaced with a bisazo compound (G-(3)) represented by the following structural formula. When a photoreceptor was prepared and a copied image was evaluated in the same manner as in Example 8, only images with a lot of fog were obtained. Also, as copying is repeated,
The contrast of the copied image decreased, and after 2000 repetitions, almost no copied image could be obtained. Example 9 A layer of vinyl chloride-vinyl acetate-maleic anhydride copolymer "Eslec MF-10" (manufactured by Sekisui Chemical Co., Ltd.) was placed on a conductive support made of aluminum foil laminated on a polyester film.
A 0.05 μm intermediate layer is provided, and exemplified compound B is placed on top of the intermediate layer.
-(4) 5g and polycarbonate resin "Panlite L"
-1250'' (manufactured by Teijin Kasei Co., Ltd.) was added to 100 ml of dichloromethane and dispersed in a ball mill for 24 hours, and the dispersion was applied to a dry film thickness of 10 μm to prepare a photoreceptor. The photoconductor obtained in the above manner is charged with a +
E1/2 and E1/2 in the same manner as in Example 1 except that 6KV was used.
_VR was measured. The first result was E1/2 = 2.2 lux·sec and V _R = 0V. Example 10 1-Phenyl-3- as a carrier transport layer on a polyester film deposited with aluminum
6 g of (p-diethylaminostyryl)-5-(p-diethylaminophenyl) pyrazoline and 10 g of polyester resin "Vylon 200" (manufactured by Toyobo Co., Ltd.) were dissolved in 70 ml of 1,2-dichloroethane, and this solution was dried. The coating was applied to a film thickness of 10 μm. Next, 1 g of exemplified compound B-(12) and B
-(13) in 110 ml of 1,2-dichloroethane and dispersed in a ball mill for 24 hours. The dispersion was coated to a dry film thickness of 0.5 μm to form a carrier generation layer, and the photoreceptor of the present invention was formed. When the thus obtained photoreceptor was evaluated in the same manner as in Example 9, it was found that E1/2 = 2.2 lux·sec and V _R = +5V. Example 11 A 2% ethylenediamine solution of Exemplified Compound B-(19) was applied onto a polyester film laminated with aluminum so that the film thickness after drying was 0.5 μm to form a carrier generation layer. Furthermore, 1-[4-(N,N
-diethylamino)benzylidene]-amino-1,
2,3,4-tetrahydroquinoline (compound K-(7) below), 1-(1-ethyl-4-carbazolyl)
Methylideneamino-1,2,3,4-tetrahydroquinoline (compound K-(8) below) or 4-methoxy-4'-(4-chloro)-styryl-triphenylamine (compound K-(9) below) ) separately about 10g each and polycarbonate Resin (manufactured by Teijin Chemicals, Panlite L-1250) 14g
A solution prepared by dissolving 1,2-dichloroethane in 140 ml was coated so as to have a dry film thickness of 12 μm, and dried to obtain photoreceptors containing three different carrier transport substances. These three types of photoreceptors were manufactured by Kawaguchi Electric Manufacturing Co., Ltd.
The following characteristics were evaluated using an electrostatic paper tester model SP-428 manufactured by Co., Ltd. Charged for 5 seconds at a charging voltage of -6KV,
After leaving this in the dark for 5 seconds, halogen light is irradiated so that the material surface illuminance is 35 lux, and the exposure amount required to attenuate the surface potential by half (half-reduced exposure amount,
E1/2) was measured. In addition, the surface potential (residual potential) V _R after exposure with an exposure amount of 30 lux·sec was measured. As shown in Table 5, the results were good in combination with any carrier transport material.

[Table] Comparative Example 4 A comparative photoreceptor was prepared in the same manner as in Example 11, except that the exemplified compound B-(19) was replaced with the following bisazo compound (G-(4)), and the characteristics were evaluated. result, As shown in Table 6, the results varied depending on the carrier transport substance.

[Table] Example 12 On the conductive support provided with the intermediate layer used in Example 5, 2 g of Exemplified Compound B-(2) and 100 ml of 1,2-dichloroethane were well dispersed and mixed, and the membrane after drying was prepared. A carrier generation layer was prepared by coating it to a thickness of 0.3 μm. Then thereon as a carrier transport substance, 4.
6 g of 4'-dimethyl-4''-styryl-triphenylamine (compound K-(10) below) and polycarbonate "Panlite L-1250" (manufactured by Teijin Chemicals) A photoreceptor of the present invention was prepared by dissolving 10 g of 1,2-dichloroethane in 90 g of 1,2-dichloroethane and coating the solution so that the film thickness after drying was 10 μm to form a carrier transport layer. The electrophotographic properties of this photoreceptor at room temperatures of 25° C. and 60° C. were measured in the same manner as in Example 7. The results are shown in Table 7.

[Table] As is clear from the above results, the photoreceptor of the present invention has good sensitivity and residual potential characteristics even at high temperatures, and is stable against heat. Example 13 2 g of Exemplified Compound B-(3) and 110 ml of 1,2-dichloroethane were well dispersed and mixed on the conductive support provided with the intermediate layer used in Example 5, and the film thickness after drying was
A carrier generation layer was created by coating the film to a thickness of 0.3 μm. In order to test the durability of this carrier generation layer against UV light, an ultra-high pressure mercury lamp (manufactured by Tokyo Shibaura Electric Co., Ltd.) was placed 30 cm away from the carrier for 10 minutes.
UV light of 1500 cd/cm ² was irradiated. Then this UV
7 g of 1-(1-ethyl-4-carbazolyl)methylideneamino-1,2,3,4-tetrahydroquinoline (compound K-(11) below) was added as a carrier transport substance onto the light-irradiated carrier generation layer. 10 g of polycarbonate [Panlite L-1250] (manufactured by Teijin Chemicals) and 1,2-dichloroethane A carrier transport layer was formed by applying a solution dissolved in 90 g to a dry film thickness of 12 μm, thereby producing a photoreceptor of the present invention. The same measurements as in Example 5 were performed on this photoreceptor. The results are shown in Table 8. Example 14 A photoreceptor of the present invention was prepared in the same manner as in Example 13, except that UV light was not irradiated after the carrier generation layer was formed, and the same measurements as in Example 5 were performed. The results are shown in Table 8.

[Table] As is clear from the above results, the photoreceptor of the present invention has excellent sensitivity and residual potential characteristics against UV light irradiation, has small fluctuations in acceptance potential, and is stable against light. can. Comparative Example 5 Compound B-(3) was converted into the following bisazo compound (G-
A photoreceptor was formed in the same manner as in Example 13 and Example 14 except that (5)) was changed, The same measurements as in Example 5 were performed. The results are shown in Table 9.

〔Effect of the invention〕

According to the present invention, by using the azo compound represented by the above general formula [] as a photoconductive substance constituting the photosensitive layer of the photoreceptor, it is possible to achieve stability against heat and light, which is the object of the present invention. It is also an excellent photoreceptor that has excellent electrophotographic properties such as charge retention, sensitivity, and residual potential, and has little fatigue change even after repeated use, and has sufficient sensitivity even in the long wavelength region of 780 nm or more. can be created.

[Brief explanation of the drawing]

FIGS. 1 to 6 are cross-sectional views showing examples of the mechanical structure of the photoreceptor of the present invention.
~7 represents the following, respectively. 1... Conductive support, 2... Carrier generation layer,
3... Carrier transport layer, 4... Photosensitive layer, 5... Intermediate layer, 6... Layer having a carrier transport substance, 7...
...Carrier generating substance.

Claims (1)

[Scope of Claims] 1. A photoreceptor comprising a photosensitive layer containing an azo compound of the following general formula [] on a conductive support. General formula [] [In the formula, Y ₁ and Y ₂ each represent an alkyl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, or a hydroxy group, l is an integer of 0 or 1, and m and n are integers of 0 to 3. represent. However, m and n never become 0 at the same time. A is [Formula] [Formula] [Formula] or [Formula], Z is an atomic group necessary to constitute a substituted or unsubstituted aromatic carbocycle, or a substituted or unsubstituted aromatic heterocycle, Q is a substituted or unsubstituted carbamoyl group, or a substituted or unsubstituted sulfamoyl group, R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted carbamoyl group, or a carboxyl group and its ester group or cyano group, A' is a substituted or unsubstituted aryl group, R ₂ and R ₃ are substituted or unsubstituted alkyl groups, substituted or unsubstituted aralkyl groups,
Or represents a substituted or unsubstituted aryl group. 2. The photoreceptor according to claim 1, wherein the photosensitive layer contains a carrier transporting substance and a carrier generating substance, and the carrier generating substance is an azo compound of the general formula []. 3. The photoreceptor according to claim 1 or 2, wherein the photosensitive layer is constituted by a laminate of a carrier generation layer containing a carrier generation substance and a carrier transport layer containing a carrier transport substance.