JPH01314250A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain high sensitivity, small residual potential, unchangeable characteristics even at the time of repeated uses, and superior durability by incorporating a specified asymmetric squarium compound excellent in carrier generating function. CONSTITUTION:The asymmetric squarium compound to be used is represented by formula I in which one of Ar1 and Ar2 is a group represented by formula II and the other is represented by formula III; each of R0, R1, and R2 is H, halogen, alkyl, or the like; Y is -SO2-R8; R8 is H, alkyl, or the like; each of R3-R6 is H, halogen, or alkyl; R9 is alkyl or the like; each of R10 and R11 is alkyl or phenyl; and R12 is H, OH, methyl, or the like, thus permitting electrophotographic characteristics, such as sensitivity, resistance to rise of residual potential, and potential stability to be enhanced and deterioration due to fatigue to be reduced at the time of repeated uses.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a photosensitive layer containing a specific asymmetric squareium compound.

[Prior Art] Conventionally, inorganic photoreceptors having a photosensitive layer containing an inorganic photoconductive compound such as selenium, zinc oxide, cadmium sulfide, or silicon as a main component have been widely used as electrophotographic photoreceptors. However, these are not necessarily satisfactory in terms of sensitivity, thermal stability, moisture resistance, durability, manufacturing cost, etc. For example, when selenium crystallizes, its properties as a photoreceptor deteriorate, making it difficult to manufacture.Also, selenium crystallizes due to heat, fingerprints, etc., and its performance as a photoreceptor deteriorates. In addition, cadmium sulfide has problems with moisture resistance and durability, and zinc oxide has problems with 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. 5G-10496 describes an organic photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2,4,7-dolinitro-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.

[Problems to be Solved by the Invention] Many compounds have been proposed as carrier-generating substances in the above-mentioned functionally separated electrophotographic photoreceptor. An example of using an inorganic compound as a carrier generator is amorphous selenium described in Japanese Patent Publication No. 43-16198, which is used in combination with an organic photoconductive compound. The drawback that the carrier generation layer made of selenium crystallizes due to heat and deteriorates the characteristics as a photoreceptor has not been improved.

Furthermore, many electrophotographic photoreceptors using organic dyes or organic pigments as carrier-generating substances have been proposed. Typical examples include bisazos, trisazos, phthalocyanines,
Viryliums, squareiums, etc. are known.
Phthalocyanines, trisazos, and squaliums have been reported to have sensitivity from the visible region to the near-infrared region.

However, phthalocyanines have the disadvantage that their spectral sensitivity is biased toward long wavelengths and red color reproducibility is poor, and trisazo compounds do not have excellent electrical properties and sufficient sensitivity.

Although the squalium compounds disclosed in Japanese Patent Application Laid-open No. 49-105536 have relatively high sensitivity, they have drawbacks in chargeability, dark decay, etc., and have not been able to achieve both high sensitivity and low dark decay.

Furthermore, in recent years, Ar laser has been used as a light source for electrophotographic photoreceptors.
Gas lasers such as l-1e-Ne lasers and semiconductor lasers are beginning to be used. These lasers are characterized by being capable of 0N10FF in time series, and are particularly promising as a light source for copying machines with image processing functions, such as intelligent copiers, 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 acoustic engineering elements, and they can be made smaller and lighter. However, this semiconductor laser has a lower output than a gas laser, and the oscillation wavelength is also long (approximately 78 On- or more), so the spectral sensitivity of conventional electrophotographic photoreceptors is on the short wavelength side. However, there were no practically satisfactory sensitivity characteristics.

[Object of the Invention] An object of the present invention is to provide an electrophotographic photoreceptor containing a specific asymmetric squareium compound having excellent carrier generation ability.

Another object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity, low residual potential, and excellent durability whose characteristics do not change even after repeated use.

Yet another object of the present invention is to provide an electrophotographic photoreceptor containing an asymmetric squalium compound that can effectively act as a carrier generating substance even in combination with a wide variety of carrier transporting proboscises.

Still another object of the present invention is to provide an electrophotographic photoreceptor that has sufficient practical sensitivity even to long wavelength light sources such as semiconductor lasers.

Still other objects of the present invention will become apparent from the description in Mei Jllll.

[Means for Solving the Problems] As a result of intensive research to achieve the above object, the present inventors discovered that a specific asymmetric squareium compound can act as an active ingredient of an electrophotographic photoreceptor. , has completed the present invention.

That is, the above object of the present invention is achieved by an electrophotographic photoreceptor characterized by having a photosensitive layer containing an asymmetric squareium compound represented by the following general formula [I] on a conductive support. Ru.

[Wherein, Ar+ and Ar2 are different from each other, one of Ar+ and Ar2 is selected from the following general formula [A], (Ro, R1 and R2 are each a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, hydroxyl group or NH
Represents Y, Y is -C-R7 or -802-Ra
(R7 and Ra each represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a phenyl group). R3-R4mR5 and R6 each represent a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl group. R9 represents a substituted or unsubstituted alkyl group. ) The other of Ar1 and Ar2 has the following general formula [8
1, [C] or [D].

General formula [81 (wherein, Rlo and Rtt, when each independently represents a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted phenyl group, , or R+.

and Rlt may cooperate with each other to form a 3- to 7-membered nitrogen-containing heterocycle. Rlt represents a hydrogen atom, a hydroxyl group, a methyl group, a trifluoromethyl group, a halogen atom, or a carboxyl group. ) General formula [C] (wherein R13 is Rlo and Ru of the general formula [B]
(However, except when Rto and R11 jointly form a ring), R14 is the same as Rlt in the general formula [81], and R45 is a hydrogen atom, a carbon atom number of 1 to 6 alkyl group, hydroxyl group, alkoxy group having 1 to 4 carbon atoms, halogen atom, nitro group, cyano group, carboxyl group, alkoxycarbonyl group having 1 to 4 carbon atoms, or trifluoromethyl group. ) General formula [D] (wherein, Rls has the same meaning as R12 in the general formula [B1), and RR and Rto each represent Rt in the general formula [C]
It is synonymous with o. ) The asymmetric squalium compound of the present invention will be specifically shown below.

The asymmetric squalium compound of the present invention has the general formula [I]
where either Ar1 or Ar2 is selected from the above-mentioned general formula [A]. General formula [A
], the alkyl group represented by Ro, R+ and R2 is preferably an alkyl group having 1 to 7 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. This alkyl group includes those having a substituent, and typical examples of the substituent include a halogen atom, a hydroxyl group, an alkoxy group, and the like. Specific examples of alkyl groups include:
Examples include a methyl group, an ethyl group, a chloromethyl group, and among these, a methyl group is preferred.

Examples of the halogen atom represented by Ro, R+, and R2 include a chlorine atom, a bromine atom, a fluorine atom, and the like.

The alkoxy groups represented by Ro, R+ and R2 preferably have 1 to 7 carbon atoms, and specific examples thereof include methoxy and ethoxy groups.

Y of NHY represented by Ro, R1 and R2 is -C-
Although R7 or -802-R8 is shown, examples of the alkyl group which may have a substituent for R7 and R8 include a methyl group, an ethyl group, and a propyl group. Examples of the phenyl group include a phenyl group and anisoyl group.

Examples of the alkyl group for R9 include methyl group, ethyl group, propyl group, heptyl group, and the like.

Specific examples of the asymmetric squalium compound useful in the present invention are shown below, but the asymmetric squalium compound of the present invention is not limited thereto.

Below is a blank example compound! death! The asymmetric squarium compound of the present invention represented by the general formula [I] is, for example, specifically disclosed in No. 62-267753 and Tetrahedron Letters N(1,10,1) 9.781-7.
82.1970 and Synthesis
) pp, 961. According to the description in 1980, it can be synthesized in four steps as shown by the formula below.

In the first step, thionyl chloride and N,N-dimethylformamide are added to squaric acid of formula (A) and reacted at about 100°C.
2-dione is obtained.

In the second step, the 3゜4-dichloro-3-cyclobutene-1,2-dione of formula (B) obtained in the first step is added to
5 molar ratio of Ar2-H of formula (C) and the above Ar2 in a solvent.
The reaction is carried out at a temperature below room temperature in the presence of AffiCffi3 in a molar ratio of 1 or more to -H to obtain a compound of formula (D>).

Examples of the solvent used in the second step include solvents commonly used in Friedel-Crauff reactions, such as dichloromethane, carbon tetrachloride, and 1,2-dichloroethane. In addition, aluminum chloride, antimony chloride, iron chloride,
Lewis acids such as titanium chloride, boron trifluoride, tin chloride, bismuth chloride, and zinc chloride may also be used.

In the third step, the compound of formula (D) obtained in the reaction of the second step is hydrolyzed to form a compound of formula (E).

Hydrolysis can be carried out, for example, by refluxing in acetic acid containing a small amount of water.

In the fourth step, the compound of formula (E) obtained and isolated in the third step is refluxed in a solvent or by a reduced pressure method to Ar+ − of formula (F).
The target asymmetric squarium compound (I> is obtained by reacting with H. The solvent used here has a carbon number of 2
1 to 10 primary or secondary alcohols, or azeotropic mixtures of these alcohols and aromatic hydrocarbons such as benzene, toluene, and xylene can be used.

The asymmetric squalium compound of the present invention can also be obtained by a general synthesis method for squalium compounds. That is, a total of 2 moles of two different types of amine derivatives can be simultaneously reacted with 11 moles of Square Link F. However, the squalium compound obtained at this time is a mixture of an asymmetric squalium compound and a symmetric squalium compound, and it is difficult to control the ratio of the products,
The former method is preferable because it is difficult to separate and purify individual products, and there are problems such as large variations in electrical properties and a decrease in sensitivity.

Next, a specific method for synthesizing the asymmetric squareium of the present invention is not shown below.

Synthesis example (synthesis of exemplified compound 21) (Synthesis of dicyclobutenedione (B)) Squaric acid 1
00g of benzene 500-, thionyl chloride 140d and N
, N-dimethylformamide 511Q was added, and the external temperature was 10
Stir at 0°C for 2 hours. After distilling off the solvent, it is crystallized from n-hexane. After washing with n-hexane several times by decantation, drying under reduced pressure gave 58 g of dicyclobutenedione (B).
(yield 44%).

The following are blank spaces; (Synthesis of chloride (D)) 539 aluminum chloride is added to 360 d of methylene chloride, and the mixture is stirred at 0°C using a ladle. Dicyclobutenedione (B) 50
! After adding II, aniline derivative (C) 77(+ is dissolved in 120 d of methylene chloride and added dropwise while keeping the internal temperature at 0°C. Stir at internal temperature of 0°C for 6 hours.

Add 12 ml of methylene chloride and 1 ml of distilled water, stir, and leave to stand to remove 1 q of methylene chloride layer. After washing with water, dry with a sieve, and methylene chloride is distilled off under reduced pressure. Purified with a silica gel column, 94 g of crystalline product (D) (
Yield: 82%) 19.

(Synthesis of OH form (E)) Vinegar M10Qd and distilled water 10- are added to 31 g of chlorine form (D), and heated under reflux for 3 hours with stirring.

After cooling, add 4y of distilled water, add 50% hydrochloric acid and stir.
Filter with a suction funnel. Washed with water, n-hexane, dried under reduced pressure, 0)-1 body (E) 23! 1 (yield 78%) was obtained in the form of crystals.

(Synthesis of Exemplary Compound 21) Add 1-heptatool 1 and compound (F) 12 () to OH form (E) 23 (), stir and heat under reflux for 2 hours under reduced pressure. Suction filtration while hot. Washed three times with acetone 2J2 and dried under reduced pressure to obtain 21 g (yield: 64%) of target exemplary compound 21 as green crystals.

Elemental analysis HN Calculated value (%) 73.58 5.53 6.13
Actual value (%) 73.54 5,55 6.07
Spectral absorption spectrum (in methylene chloride) λ1IlaX
=640nRI Infrared absorption spectrum (in KBr) vma×=15! JOcn+-' (c=o) Melting point (
Japanese Pharmacopoeia melting point measurement method) 240°C The asymmetric squareium compound of the present invention has excellent photoconductivity, and when a photoreceptor is manufactured using the compound, the asymmetric square of the present invention is placed on a conductive support. Although it can be produced by providing a photosensitive layer in which a squareium compound is dispersed in a binder, it can be produced as a carrier generating substance by utilizing the particularly excellent carrier generating ability of the photoconductivity of the asymmetric squareium compound of the present invention. Particularly excellent results can be obtained when a so-called functionally separated type photoreceptor is constructed by using a carrier transport substance that can effectively act in combination with the photoreceptor. The functionally separated photoreceptor may be of a dispersed type, but it is more preferably a laminated type photoreceptor in which a carrier generation layer containing a carrier generation substance and a carrier transport layer containing a carrier transport substance are laminated.

When the asymmetric squalium compound of the present invention is used as a carrier-generating substance, carrier-transporting substances that can be used in conjunction with it include electron-accepting substances that easily transport electrons, such as trinitrofluorenone or tetranitrofluorenone. , polymers having a side chain of a heterocyclic compound such as poly-N-vinylcarbazole, triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives, polyarylalkane derivatives, phenylenediamine derivatives, hydrazone derivatives, Electron-donating substances that easily transport holes, such as amine-substituted carbon derivatives, triarylamine derivatives, carbazole derivatives, stilbene derivatives, fenodef 92113 derivatives, azine derivatives, butadiene derivatives, and Schiff base derivatives, can be used in the present invention. Carrier transport substances are not limited to these.

Various types of mechanical configurations of photoreceptors are known, and the photoreceptor of the present invention can take any of these forms.

Usually, the configuration is as shown in FIGS. 1 to 6. FIG. 1 shows an example of a photoreceptor for negative charging, in which a carrier generation layer 2 containing the above-mentioned asymmetric squareium compound as a main component is formed on a conductive support 1, and a carrier containing a carrier transporting substance as a main component is formed on the carrier generation layer 2. This is the case where the photosensitive layer 4 has the transport layer 3 in a laminated structure.

FIG. 2 shows an example of a photoreceptor for positive charging, in which a carrier generation layer 2 is provided on a carrier transport layer 3.

In this case, in order to protect the carrier generation layer, it is desirable to form an overcoat layer or an intermediate layer on the carrier generation layer.

As the overcoat layer, various scale binders can be used, but acrylic resin, isocyanate resin, etc. are preferable. Furthermore, tin oxide, titanium oxide, etc. can also be dispersed in the binder.

As the intermediate layer, the same binders and metal oxides as those for the overcoat layer can be used. Furthermore, compounds containing silicon or zirconium can also be used.

As shown in FIGS. 3 and 4, this photosensitive layer 4 may be provided via an intermediate layer 5 provided on a conductive support. When the photosensitive layer 4 has a two-layer structure in this manner, a photoreceptor having the most excellent electrophotographic properties can be obtained. Further, in the present invention, as shown in FIGS. 5 and 6, a photosensitive layer 4 comprising a carrier generating substance 7 and a carrier transporting substance dispersed in a layer 6 is formed on the conductive support 1 directly or in an intermediate manner. It may be provided via layer 5.

The carrier generation layer 2 constituting the two-layered photosensitive layer 4 may be applied directly to the conductive support 1 or the carrier transport layer 3, or if necessary, after providing an intermediate layer such as an adhesive layer or a barrier layer, for example. It can be formed by the following method.

M-1, Name of the Invention A method of applying a solution in which a squalium compound is dissolved in a suitable solvent, or a solution in which a binder is added and mixed as necessary.

M-2) A method in which the asymmetric squalium compound of the present invention is made into fine particles in a dispersion medium using a ball mill, a homomixer, etc., and a binder is added as necessary to mix and disperse the resulting dispersion.

Solvents or dispersion media used to form the carrier generation layer include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N,N-dimethylformamide, acetylene, methylethylketone, and cyclohexanone. , benzene, toluene, xylene, chloroform, 1.2-dichloroethane, 1,1.2-trichloroethane, 1.1.1-trichloroethane, trichloroethane, tetrachloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropane tools, ethyl acetate, butyl acetate, dimethyl sulfoxide, and the like.

When using a binder in the carrier generation layer or carrier transport layer, any binder can be used, but it is preferable to use a film-forming polymer that is hydrophobic, has a high dielectric constant, and is electrically insulating. preferable. Examples of such high molecular weight polymers include the following:
It is not limited to these.

P-1) Polycarbonate P-2) Polyester P-3) Methacrylic resin P-4) Acrylic resin P-5) Polyvinyl chloride P-6) Polyvinylidene chloride P-7) Polystyrene P-8) Polyvinyl acetate P-9 ) Styrene-butadiene copolymer p -io) Vinylidene chloride-acrylonitrile copolymer p-11) Vinyl chloride-vinyl acetate copolymer P-1
2) Vinyl chloride-vinyl acetate-maleic anhydride copolymer p-13) Silicone resin p-14) Silicone-alkyd resin P-15) Phenol formaldehyde resin p-16) Styrene-
Alkyd resin p-17) Poly-N-vinyl carbazole p-18) Polyvinyl butyral p-19) Polyvinyl formal p-20) Vinyl acetate resin P-21) Epoxy resin These binders may be used alone or in combination. It can be used as a mixture of the above.

The thickness of the carrier generation layer 2 formed in this way is
It is preferably 0.05 μm to 20 μm, more preferably 0.05 μm to 5 μm. Further, when the carrier generation layer or the photosensitive layer is a dispersion system, the asymmetric squalium compound preferably has a displacement of 5 μm or less, more preferably 1 μm or less.

As a conductive layer, a non-conductive conductive compound such as titanium oxide, tin oxide, copper iodide, carbon,
It can be formed by dispersing an organic conductive compound such as an organic semiconductor or a conductive polymer in a binder or by applying it as it is.

The asymmetric squarium compound of the present invention can be subjected to various processing to improve its dispersibility from the viewpoint of powder and granule engineering. For example, wet granulation, spray drying, freeze drying, dry pulverization, etc. can be used.

Further, by changing the crystal form, electrophotographic performance and dispersibility can be improved. For example, the crystal form may change depending on the method of dissolving with an organic amine and then neutralizing and precipitating with an acid, or depending on pressure, temperature, etc.

The conductive support used in the photoreceptor of the present invention includes a metal plate including an alloy, a metal drum, a conductive polymer,
Examples include paper, plastic films, etc., which have achieved II electrification by coating, vapor depositing, or laminating a thin layer of metal such as aluminum, palladium, gold, etc., including a 1ift compound or alloy such as indium oxide.

As an intermediate layer such as an adhesive layer or a barrier layer, in addition to the polymer used as the binder, an organic polymer material such as polyvinyl alcohol, ethyl cellulose, carboxymethyl cellulose, or aluminum oxide is used.

The photoreceptor of the present invention has the above-described structure, and as is clear from the examples described later, it has excellent charging characteristics, sensitivity characteristics, and image forming characteristics, and is particularly resistant to fatigue even when used repeatedly. It has little deterioration and excellent durability.

[Examples] The present invention will be specifically explained below using Examples, but the embodiments of the present invention are not limited thereto.

(Example 1) In a 300 d stainless steel pot, 0.75 d of polyvinyl butyral resin (trade name, XYHL), 150 d of tetrahydrofuran, and 1 1.5 d of asymmetric squalium compound.
(+), add Glass Peas 150iQ, and disperse with a sand grinder for 48 hours. Apply this dispersion liquid onto an aluminum vapor-deposited base with a wire bar so that the film thickness after drying is approximately 0.2μ, and then apply it to the carrier. Generation layer (CGL)
was formed. Next, polycarbonate resin (trade name, Panlite) 7.5 (], ethylene chloride 50112, the following carrier transport substance and -14,0a are mixed with a magnetic stirrer. This liquid is placed on the CGL, A carrier transport II (CTL) was formed by applying with an applicator so that the film thickness after drying was 20 μm.

After being placed in the oven and thoroughly dried, the electrophotographic performance was tested. That is, after being charged by performing a corona discharge of 16 KV for 5 seconds using an electrostatic copying tester manufactured by Kawaguchi Electric,
Leave it at B81 for 5 seconds, measure its surface potential V^, then irradiate the photosensitive layer with a tungsten halogen lamp with an illuminance of 14 lux, and calculate the time until the surface potential becomes half of ■^. Then, the half-reduced exposure amount E 1/2 was determined. As a result, VA -1200V, E 1/2 = 2.
It was 41ux @ sec.

Next, image characteristics and durability were tested using an LD printer manufactured by Konica ■ (semiconductor laser with a light source of 790 nm±10 na+). Good images were obtained in a picture printing test of up to 10,000 sheets.

Examples 2 to 10 Photoreceptors were prepared by changing the carrier generating substance (CGM) 1 and the carrier transporting substance (CTM) K-1 as shown in Table 1 in Example 1, and electrophotography was carried out in the same manner as in Example 1. Performance was evaluated. The results are shown in Table 1.

Table 1 The CTMs in Table 1 are shown below.

-2 -3 -4 -5 -6 -9 -10 Example 11 The photoconductor was prepared in the same manner as in Example 1, except that the order of CGL and CTL was reversed. was prepared and tested. (However, the corona charge was set to +6KV.) The results are VA
-1150V, E 1/2-2.711jX・see
Met. In addition, the images in the image display test of up to 10,000 sheets were good.

fruit! ii! 112-20 In Example 11, a photoreceptor was prepared by changing the carrier generating material (CGM) 2 and the carrier transporting material (CTM) K-1 as shown in Table 2, and the electrophotographic performance was improved in the same manner as in Example 11. evaluated. The results are shown in Table 2.

The following thread ゛, white ゛ Table 2 The CTMs in Table 2 are shown below.

-11 to -12 to -13 to -15 to -18 to H3 to -19 to -20 to the following margins [Effect of the invention] According to the present invention, the light constituting the photosensitive layer of the electrophotographic photoreceptor is By using the non-squarium compound represented by the general formula [I] as the conductive substance, it has excellent electrophotographic properties such as sensitivity, residual potential, and charge retention, and has little fatigue deterioration when used repeatedly. It is possible to create an immersed electrophotographic photoreceptor that is stable against heat and light, has sufficient sensitivity even in the long wavelength region of 780 nm or more, and can be used sufficiently even in the visible light region of 780 nm or less. . Further, by using the asymmetric squalium compound of the present invention, it is possible to provide a photoreceptor having sufficient sensitivity even in combination with a wide variety of carrier transport substances.

[Brief explanation of the drawing]

1 to 6 are sectional views showing examples of the mechanical structure of the electrophotographic photoreceptor of the present invention, and 1 to 7 in the figures represent the following, respectively. 1... Conductive support 2... Carrier generation layer 3... Carrier transport layer 4... Photosensitive layer 5... Intermediate layer 6... Layer containing carrier transport substance 7... Carrier generation material

Claims (3)

[Claims] (1) An electrophotographic photoreceptor comprising, on a conductive support, a photosensitive layer containing at least one asymmetric squarium compound represented by the following general formula [I]. General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, Ar_1 and Ar_2 are different from each other,
One of _1 and Ar_2 is selected from the general formula [A] below, and the general formula [A] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R_0, R_1 and R_2 are hydrogen atoms, halogen atoms, alkyl groups, alkoxy represents a group, a hydroxyl group, or NHY.
hydrogen atom, substituted or unsubstituted alkyl group,
Or represents a phenyl group. ). R_3, R_
4, R_5 and R_6 each represent a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl group. R_9 represents a substituted or unsubstituted alkyl group. ) The other of Ar_1 and Ar_2 is selected from the following general formula [B], [C], or [D]. General formula [B] ▲ Numerical formulas, chemical formulas, tables, etc.
20 substituted or unsubstituted alkyl groups, substituted or unsubstituted phenyl groups, or R_1_0 and R_1
_1 may jointly form a 3- to 7-membered nitrogen-containing heterocycle. R_1_2 represents a hydrogen atom, a hydroxyl group, a methyl group, a trifluoromethyl group, a halogen atom, or a carboxyl group. ) General formula [C] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1_3 has the same meaning as R_1_0 and R_1_1 in the above general formula [B] (However, R_1_0 and
_1), R_
1_4 is synonymous with R_1_2 in the general formula [B],
R_1_5 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a nitro group, a cyano group, a carboxyl group, an alkoxycarbonyl group having 1 to 4 carbon atoms. Or it represents a trifluoromethyl group. ) General formula [D] ▲ Numerical formulas, chemical formulas, tables, etc. ) (2) The electronic photosensitive layer according to claim (1), wherein the photosensitive layer contains a carrier transporting substance and a carrier generating substance, and at least one of the carrier generating substances is an asymmetric squarium compound represented by the general formula [I]. Photographic photoreceptor. (3) The photosensitive layer has a laminated structure of a carrier-generating layer containing an asymmetric squarium compound represented by the general formula [I] as a carrier-generating substance, and a carrier-transporting layer containing a carrier-transporting substance. The electrophotographic photoreceptor described in 1) or (2).