In a positively charging single layer type electrophotographic photoreceptor having an over coat layer, an electrophotographic photoreceptor that is excellent in mechanical strength, electric characteristics, and adhesiveness, an electrophotographic photoreceptor cartridge, and an image formation device are provided. In a positively charging electrophotographic photoreceptor having a single layer type photosensitive layer and an over coat layer, the Martens hardness on the photoreceptor surface satisfies the prescribed condition, and preferably the photosensitive layer satisfies the particular relational expression of the contents and the molecular weights of the hole transporting substance and the electron transporting substance contained therein, thereby solving the problem.

An electrophotographic photoreceptor includes a conductive substrate, and a lamination type photosensitive layer disposed on the conductive substrate and including a charge generation layer and a charge transport layer, in which the charge transport layer contains a polyester resin (1) having a dicarboxylic acid unit (A) represented by Formula (A) and a diol unit (B) represented by Formula (B), and a charge transport material, and in a case where a weight-average molecular weight Mw of the polyester resin (1) contained in the charge transport layer is defined as A (10,000), a value of a ratio M1/M2 of a mass M1 of the charge transport material contained in the charge transport layer to a mass M2 of the charge transport layer is defined as Cs, and an average thickness of the charge transport layer is defined as Ds (μm), expressions of 5≤A≤40, 0.28≤Cs≤0.55, 27≤Ds≤50, and 2.5≤(A×Ds)/(Cs×100)≤70.0 are satisfied.

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In Formula (A), n.sup.1 represents 1, 2, or 3, n.sup.1 number of m.sup.1's each independently represent 0, 1, 2, 3, or 4, m.sup.1 number of Ra.sup.1's each independently represent an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms.

In Formula (B), Rb.sup.1 and Rb.sup.2 each independently represent a hydrogen atom, an alkyl group having 1 or more and 20 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, or an aralkyl group having 7 or more and 20 or less carbon atoms, Rb.sup.3, Rb.sup.4, Rb.sup.5, Rb.sup.6, Rb.sup.7, Rb.sup.8, Rb.sup.9, and Rb.sup.10 each independently represent a hydrogen atom, an alkyl group having 1 or more and 10 or less carbon atoms, an aryl group having 6 or more and 12 or less carbon atoms, an aralkyl group having 7 or more and 20 or less carbon atoms, or an alkoxy group having 1 or more and 6 or less carbon atoms, and Rb.sup.1 and Rb.sup.2 may be bonded to each other to form a cyclic alkyl group.

The present invention relates to an electrophotographic photoreceptor comprising: a conductive support; and a photosensitive layer on the conductive support, wherein the photosensitive layer contains a charge transport substance, a binder resin, and a compound which has a molecular weight of equal to or less than 350, and is represented by General Formula (1).

An electrophotographic photosensitive member includes a single-layer type photosensitive layer including phthalocyanine or a derivative thereof and an electron transport material. The electron transport material includes at least one first compound represented by formula (1) or (2) shown below and at least one second compound represented by formula (3), (4), or (5) shown below. A total amount of the at least one first compound and the at least one second compound is no less than 60 parts by mass and no greater than 120 parts by mass relative to 100 parts by mass of the binder resin. An amount of the at least one first compound is no less than 35 parts by mass and no greater than 80 parts by mass. An amount of the at least one second compound is no less than 25 parts by mass and no greater than 40 parts by mass. ##STR00001##

There is provided an electrophotographic photoreceptor including: a conductive support; and a photosensitive layer and a protective layer containing a cured product obtained by curing a curable compound, which are sequentially disposed on the conductive support. An area ratio A/B is 0.0045 or less, where A is an absorbance area at a wavelength of 1647 cm.sup.−1 to 1627 cm.sup.−1 and B is an absorbance area of a peak at a wavelength of 1800 cm.sup.−1 to 1647 cm.sup.−1 in an infrared absorption spectrum measurement of the protective layer. The photosensitive layer contains at least a hole transport material (HTM) and a radical acceptor compound. The electrophotographic photoreceptor is an electrophotographic photoreceptor including a protective layer with a high curing degree and having good initial electrical characteristics, excellent strong exposure characteristics, and excellent transfer repeatability.

An electrophotographic photoreceptor includes a conductive support, an undercoat layer on the conductive support, and a charge generation layer on the undercoat layer, in which the charge generation layer contains a phthalocyanine compound, the undercoat layer contains an electron transport compound, and a difference between an energy level of the lowest unoccupied molecular orbital of the phthalocyanine compound and an energy level of the lowest unoccupied molecular orbital of the electron transport compound is less than 0.45 eV.

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

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A ratio n.sub.1/n.sub.2 of the number n.sub.1 of repeats of the repeating unit represented by formula (1) to the number n.sub.2 of repeats of the repeating unit represented by formula (2) is at least 1.0.

An electrophotographic photoreceptor, including a photosensitive layer formed on an electroconductive substrate. The photosensitive layer includes a charge-generating material and an electron-transporting material, and the electron-transporting material includes first and second electron-transporting materials. A difference in lowest unoccupied molecular orbital (LUMO) energy between the first electron-transporting material and the charge-generating material is in a range from 1.0 to 1.5 eV, and a difference in LUMO energy between the second electron-transporting material and the charge-generating material is in a range from 0.6 to 0.9 eV. A ratio of mass of the second electron-transporting material to a total of mass of the first electron-transporting material and the mass of the second electron-transporting material is in a range from 3 to 40%.

The undercoat layer contains metal particles and a polyamide resin. The metal particle has a core and a coat layer covering at least a part of the core. The core contains titanium oxide. The coat layer contains at least a metal oxide different from titanium oxide. The metal oxide different from the titanium oxide is located on the outermost surface of the metal particles. The polyamide resin has an amide bond and an alkylene group. The absorption rate of the first peak derived from the amide bond to the second peak derived from the alkylene group to the first absorbance measured by infrared spectroscopy is ≥0.70.

A photosensitive layer included in an electrophotographic photosensitive member contains at least a charge generating material, a hole transport material, and a binder resin. The hole transport material includes a compound (1). The binder resin includes a polyarylate resin having at least one repeating unit (10) and at least one repeating unit (11). Alternatively, the binder resin includes a polycarbonate resin having a repeating unit (20) and a repeating unit (21). The general formulas (1), (10), (11), (20), and (21) are as follows ##STR00001##