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 photosensitive member includes a photosensitive layer. The photosensitive layer contains a charge generating material and a hole transport material represented by general formula (1) shown below in a single layer. Titanyl phthalocyanine contained as the charge generating material exhibits a main peak at a Bragg angle 20.2=27.2 in a CuK characteristic X-ray diffraction spectrum and satisfies either (B) or (C), shown below, in a differential scanning calorimetry spectrum. (B) A peak is not present in a range from 50 C. to 400 C., other than a peak resulting from vaporization of adsorbed water. (C) A peak is not present in a range from 50 C. to 270 C., other than a peak resulting from vaporization of adsorbed water, and a peak is present in a range from 270 C. to 400 C. ##STR00001##

A triphenylamine derivative is represented by general formula (1). In general formula (1), R.sub.1 to R.sub.7 each represent, independently of one another, a chemical group selected from the group consisting of a halogen atom, an optionally substituted alkyl group having a carbon number of at least 1 and no greater than 6, an optionally substituted alkoxy group having a carbon number of at least 1 and no greater than 6, and an optionally substituted aryl group having a carbon number of at least 6 and no greater than 12. Also, k, l, m, n, o, and p each represent, independently of one another, an integer of at least 0 and no greater than 4. When any of k, l, m, n, o, or p represents an integer greater than 1, chemical groups R.sub.3, R.sub.4, R.sub.5, R.sub.6, or R.sub.7 bonded to the same aromatic ring may be the same or different. ##STR00001##

A diamine compound is represented by general formula (1). In the general formula (1), R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, and R.sub.10 each represent, independently of one another, a hydrogen atom, a halogen atom, an optionally substituted alkyl group having a carbon number of at least 1 and no greater than 6, an optionally substituted alkoxy group having a carbon number of at least 1 and no greater than 6, or an optionally substituted aryl group having a carbon number of at least 6 and no greater than 14. m represents an integer of at least 1 and no greater than 3. n represents an integer of at least 0 and no greater than 2. ##STR00001##

A naphthalenedicarboximide derivative is represented by general formula (1) or (2). In general formulas (1) and (2), R.sub.1, R.sub.2, and R.sub.3 each represent, independently of one another, an alkyl group which has a carbon number from 1 to 10 and which may have an aryl group having a carbon number from 6 to 14, an aryl group which has a carbon number from 6 to 14 and which may have an alkyl group having a carbon number from 1 to 10, a cycloalkyl group having a carbon number from 3 to 10, or an alkoxy group having a carbon number from 1 to 6, and m represents an integer from 0 to 4. When m represents an integer of 2 or more, chemical groups R.sub.2 may each be the same or may each be different.

##STR00001##

A charge transporting layer of an electrophotographic photosensitive member contains a polysiloxane resin having a terminal structure represented by the formula (1), at least one selected from the group consisting of a polycarbonate resin A having a structural unit represented by the formula (A) and a polyarylate resin B having a structural unit represented by the formula (B), and a charge transporting substance, wherein the content of the siloxane structure in the polysiloxane resin is not less than 0.5% by mass and not more than 10% by mass based on the total mass of whole resin in the charge transporting layer.

In a negatively-chargeable laminate-type electrophotographic photoreceptor, a charge generation layer and another charge transport layer are arranged on a conductive substrate directly or via an intermediate layer. The charge transport layer contains at least a hole-transporting substance, an electron-transporting substance and a binder resin; the mass ratio (R.sub.PN) [% by mass] between mass (P) of the hole-transporting substance and mass (N) of the electron-transporting substance is represented by the following equation (1), and satisfies the following equation (2):

R.sub.PN=(N/(P+N))100(1)

1R.sub.PN40(2); and

when a voltage of +6 kV is applied to the photoreceptor for 5 seconds via a resin sheet having a thickness of 50 m and a surface resistivity of 210.sup.7 /cm.sup.2, the surface potential difference (Vo) and half-tone potential difference (Vh) between before and after the voltage application are both 15 V or less.

An electrophotographic photosensitive member includes a conductive base; an organic photosensitive layer disposed on the conductive base, the organic photosensitive layer including a layer that constitutes a surface and contains a charge transport material, a binder resin, and silica particles in an amount of about 40% by weight or more; and an inorganic protective layer disposed on the organic photosensitive layer and having a surface roughness Ra of about 5 nm or less.

A method of forming an overcoat layer. The method comprises providing a substrate having an imaging structure formed thereon, the imaging structure comprising (i) a charge transport layer and a charge generating layer, or (ii) an imaging layer comprising both charge generating material and charge transport material. An overcoat composition is deposited on the imaging structure, the overcoat composition comprising a charge transport molecule, a fluorinated building block, a leveling agent, a liquid carrier and optionally a first catalyst. The fluorinated building block is a fluorinated alkyl monomer substituted at the and positions with a hydroxyl, carboxyl, carbonyl or aldehyde functional group or the anhydrides of any of those functional groups. The overcoat composition is cured to form an overcoat layer that is a fluorinated structured organic film, the curing comprising treating an outer surface of the overcoat composition with at least one cross-linking process. The crosslinking process forms a cross-linking gradient in the overcoat layer. If the overcoat composition comprises the first catalyst, there is an insufficient amount of the first catalyst to fully cross-link the overcoat layer.

A multi-layer 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 charge transport material, a binder resin, and silica particles. The charge transport layer is a monolayer. The charge transport layer is disposed as an outermost surface layer of the multi-layer electrophotographic photosensitive member. The silica particles have a content of at least 0.5 parts by mass and no greater than 15 parts by mass relative to 100 parts by mass of the binder resin. The binder resin includes a polyarylate resin. The polyarylate resin has a repeating unit represented by general formula (I) shown below. In general formula (I), R.sub.1-R.sub.3 and Y are defined as those described in the specification.

##STR00001##