An electrophotographic photoreceptor comprising at least a photosensitive layer on a conductive substrate, wherein the photosensitive layer is a laminate having a charge transport layer and a charge generation layer, the charge transport layer contains four or more types of compounds each having a maximum absorption wavelength falling within a wavelength range of from 300 nm to 600 nm in a tetrahydrofuran solution at 25? C., and maximum absorption wavelengths falling within the wavelength range of at least four types of the compounds of said four or more types of the compounds are separated from each other by 10 nm or more.

A photosensitive layer of an electrophotographic photosensitive member is a single layer and contains a charge generating material, a binder resin, an electron transport material, a hole transport material, and resin particles. The binder resin includes a polyarylate resin. The polyarylate resin includes repeating units represented by formulas (1), (2), (3), and (4).

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The repeating unit (3) has a percentage content of greater than 0% and less than 50% to the total number of repeats of the repeating units (1) and (3). The repeating unit (4) has a percentage content of at least 35% and less than 70% to the total number of repeats of the repeating units (2) and (4).

An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single-layer photosensitive layer. The photosensitive layer contains a charge generating material, a hole transport material, an electron transport material, and a binder resin. The binder resin contains a polyarylate resin. The polyarylate resin is represented by general formula (1). The hole transport material contains a compound represented by general formula (HTM1), (HTM2), (HTM3), (HTM4), (HTM5), (HTM6), or (HTM7). The photosensitive layer has a scratch resistance depth of no greater than 0.50 m. The photosensitive layer has a Vickers hardness of at least 17.0 HV. ##STR00001## ##STR00002##

An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The photosensitive layer includes a charge generating layer and a charge transport layer. The charge generating layer contains a charge generating material. The charge transport layer contains a hole transport material and a binder resin. The charge transport layer further contains an electron acceptor compound. The hole transport material includes a compound represented by general formula (1). In general formula (1), R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and R.sup.10 each represent, independently of one another, a hydrogen atom or a methyl group.

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An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer. The photosensitive layer is a single-layer photosensitive layer and contains a charge generating material, a hole transport material, an electron transport material, and a binder resin. The binder resin has a viscosity average molecular weight of at least 25,000 and no greater than 50,000. A strain at break of the photosensitive layer is at least 4.9% and no greater than 13.0%. A scratch resistant depth of the photosensitive layer is no greater than 0.50 m.

An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer having a single-layer structure. The photosensitive layer contains a charge generating material, an electron transport material, a polycarbonate resin, and a hole transport material. The electron transport material includes a compound having a halogen atom and represented by general formula (1), (2), (3), (4), or (5). The polycarbonate resin has a terminal group having a fluoro group and represented by general formula (10). The hole transport material includes a compound represented by general formula (20), (21), (22), (23), (24), (25), (26), or (27). A charge of calcium carbonate as measured by charging the calcium carbonate through friction with the photosensitive layer is at least +6.5 C/g. The photosensitive layer has a Vickers hardness of at least 17.0 HV at 45 C.

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An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer having a single-layer structure. The photosensitive layer contains a charge generating material, an electron transport material, a polycarbonate resin, and a hole transport material. The electron transport material includes a compound having a halogen atom and represented by general formula (1), (2), (3), (4), or (5). The hole transport material includes a compound represented by general formula (20), (21), (22), (23), (24), (25), (26), or (27). A charge of calcium carbonate as measured by charging the calcium carbonate through friction with the photosensitive layer is at least +6.5 C/g. A Vickers hardness of the photosensitive layer at 45 C. is at least 17.0 HV.

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The present invention is to provide a charge transport substance having high resistance to stress within electrophotographic processes, an electrophotographic photoreceptor which has excellent high-speed responsiveness, shows a sufficient residual potential, and has high resistance to stress within electrophotographic processes, an electrophotographic cartridge, and an image-forming apparatus. The invention provides a charge transport substance having a specific structure. The invention further provides an electrophotographic photoreceptor including a photosensitive layer which contains the charge transport substance having a specific structure, an electrophotographic cartridge, and an image-forming apparatus, equipped with this electrophotographic photoreceptor.

An electrophotographic photoreceptor includes a conductive substrate; and a photosensitive layer arranged on the conductive substrate and containing, as a charge generating material, any one material selected from the group consisting of titanyl phthalocyanines, metal-free phthalocyanines, chlorogallium phthalocyanines and hydroxygallium phthalocyanines; and, as an electron transporting material, a naphthalene tetracarboxylic acid diimide compound represented by Formula (1) below, where R.sup.1 and R.sup.2 each represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkylene group, an alkoxy group, an alkyl ester group, a phenyl group optionally having a substituent, a naphthyl group optionally having a substituent, or a halogen element; and R.sup.1 and R.sup.2 are optionally the same or different:

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The photoreceptor realizes a stable print density even in a low-temperature environment by suppressing a reduction in print density that is caused by potential fluctuation of the photoreceptor in the low-temperature environment.

An electrophotographic photosensitive member with suppressed potential variation even in the case that a protective layer including a cured material of a composition having a polymerizable functional group is used is provided. An electrophotographic photosensitive member including a support, a charge generation layer, a charge transport layer containing a charge transporting material, and a protective layer, in the order presented, wherein the charge transport layer contains a polycarbonate resin having a structure selected from a group A and a structure selected from a group B, and the protective layer includes a cured material of a composition containing a compound having at least a functional group selected from chain-polymerizable functional groups and sequential polymerizable functional groups.