A polyarylate resin includes at least one type of repeating unit represented by a general formula (1), at least one type of repeating unit represented by a general formula (2), and a terminal group represented by a general formula (3). R.sup.1, R.sup.2, R.sup.3, and R.sup.4 each represent, independently of one another, a hydrogen atom or a methyl group. R.sup.5 and R.sup.6 each represent, independently of each other, a hydrogen atom or a C.sub.1-4 alkyl group. R.sup.5 and R.sup.6 may bond together to represent a C.sub.5-7 cycloalkylidene group. X.sup.1 represents a divalent group represented by a chemical formula (2A), (2B), (2C), or (2D) with the proviso that when only one type of repeating unit represented by the general formula (2) is included, X.sup.1 does not represent a divalent group represented by the chemical formula (2D). R.sup.f represents a chain aliphatic group having at least one fluoro group. ##STR00001##

An electrophotographic photoreceptor includes a conductive support and a single-layer photosensitive layer. The conductive support has an outer peripheral surface with a maximum surface roughness height (Rmax) of about 4.0 m or less, and the outer peripheral surface has a recess with a depth-to-aperture size ratio (depth/aperture size) of about 0.03 or more and about 0.12 or less. The single-layer photosensitive layer is disposed on the conductive support and has a thickness of about 20 m or more and a modulus of elasticity of about 4.5 GPa or more.

An electrophotographic photosensitive member includes a conductive substrate and a single-layer photosensitive layer. The photosensitive layer contains a charge generating material, a hole transport material, an electron transport material, an additive, and a binder resin. An optical response time is in a range from 0.05 milliseconds to 0.85 milliseconds. The optical response time is a time from irradiation of a surface of the photosensitive layer charged to +800 V with pulse light having a wavelength of 780 nm to surface potential decay of the photosensitive layer from +800 V to +400 V. An optical intensity of the pulse light is set so that the surface potential of the photosensitive layer becomes +200 V from +800 V after 400 milliseconds from pulse light irradiation of the surface of the photosensitive layer charged to the +800 V. The additive includes either of both an ultraviolet absorbing agent and an antioxidant.

An electrophotographic photosensitive member includes a conductive substrate and a photosensitive layer of a single layer. The photosensitive layer contains a charge generating material, a hole transport material, an electron transport material, and a binder resin. An optical response time is at least 0.05 milliseconds and no greater than 0.85 milliseconds. The binder resin includes a polycarbonate resin including a repeating unit represented by general formula (1) shown below and a repeating unit represented by general formula (2) shown below.

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The present invention aims to provide an electrophotographic photoreceptor including a charge transport layer and being excellent in electrical properties and adhesiveness while exhibiting sufficient abrasion resistance indispensable for prolonging the life, and an electrophotographic photoreceptor cartridge and an image forming apparatus including the electrophotographic photoreceptor, which is an electrophotographic photoreceptor including a charge transport layer including at least two layers, wherein an elastic deformation ratio of a binder resin contained in a first charge transport layer which is an outermost layer and an elastic deformation ratio of a binder resin contained in a second charge transport layer satisfy a predetermined relationship.

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.

An electrophotographic photoreceptor includes a conductive substrate and a single-layer-type photosensitive layer on the conductive substrate. The single-layer-type photosensitive layer contains a binder resin, a charge generating material, an electron transporting material, and two hole transporting materials having different redox potentials. The two hole transporting materials are a hole transporting material A and a hole transporting material B that has a redox potential lower than that of the hole transporting material A. The ratio A/B of a weight of the hole transporting material A to a weight of the hole transporting material B is about 12/1 or more and about 36/1 or less.

An electrophotographic photosensitive member includes a surface layer containing a charge transporting material and a polyester resin having a specific structure.

An electrophotographic photoreceptor of a negatively-chargeable laminate-type includes a conductive substrate; a charge generation layer provided on the conductive substrate and including a charge generating material; and a charge transport layer provided on the charge generation layer and containing, as a binder resin, a copolymerized polycarbonate resin having a repeating unit represented by Formula (1); as a hole transporting substance, a compound having a structure represented by Formula (2); as an electron transporting substance, a compound having a structure represented by Formula (3), and, as an antioxidant, a compound represented by Structural Formula (4), where a mass ratio H/(B+H) represents a ratio of mass (H) of the hole transporting substance with respect to a sum of mass (B) of the binder resin and the mass (H) of the hole transporting substance, and satisfies Formula (5), 20% by massH/(B+H)35% by mass.

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Provided is a process cartridge having a charging member and an electrophotographic photosensitive member to be charged by being in contact with the charging member, wherein the electrophotographic photosensitive member has a support and a photosensitive layer in this order, and a surface layer of the electrophotographic photosensitive member has a Martens hardness of 230 N/mm.sup.2 or less.