Abstract: The present invention relates to a positive charging single-layer type electrophotosensitive material comprising a conductive substrate and a photosensitive layer formed on the conductive layer, the photosensitive layer containing a phthalocyanine compound as an electric charge generating material, wherein a large half-life exposure between a half-life exposure on positive charging and a half-life exposure on negative charging is four times or less as much as that of the other half-life exposure.

Abstract: The present invention relates to a naphthoquinone derivative of the formula (1): wherein R1 and R2 are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 alkyl group, and the electrophotosensitive material comprises a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the photosensitive layer contains the naphthoquinone derivative (1).

Abstract: The present invention provides a novel naphthoquinone derivative preferred as an electron transporting agent and an electrophotographic photosensitive material of high sensitivity which contains a novel naphtoquinone derivative having a general formula (1) ##STR1## wherein R.sup.1 represents a hydrogen atom, an alkyl group which may have a substituent, or an aryl group which may contain a substituent, and R.sup.2 represents a hydrogen atom, an alkyl group which may have a substituent, a halogenated alkyl group, an aldehyde or a nitro group. The derivative is contained in a photosensitive layer of an electrophotographic photosensitive material as an electron transporting agent.

Abstract: The present invention provides a naphthoquinone derivative represented by the general formula (1): ##STR1## wherein R.sup.1 represents an aryl group which may have a substituent; and R.sup.2 represents an alkylene group which may have a substituent, an arylene group which may have a substituent, etc.

Abstract: The present invention provides a novel tryptanthrine derivative represented by a general formula: ##STR1## wherein R.sup.1 is an oxygen atom, or group represented by a formula: ##STR2## wherein R.sup.2A and R.sup.2B are the same or different and indicate a hydrogen atom, a cyano group, an acyl group, an alkoxycarbonyl group or an alkyl group, provided that R.sup.2A and R.sup.2B are not hydrogen atoms simultaneously; andR.sup.3A, R.sup.3B, R.sup.3C, R.sup.3D, R.sup.4A, R.sup.4B, R.sup.4C and R.sup.4D are the same or different and indicate a hydrogen atom or an alkyl group which may have a substituent, provided that when R.sup.1 is an oxygen atom, any one of R.sup.3A through R.sup.4D is a cyano group.Such a tryptanthrine derivative has an excellent electron transport capability to be suitably used for the electrophotosensitive material.

Abstract: The present invention provides a tryptoanthrinimine derivative represented by the general formula (Y): ##STR1## wherein R.sup.A to R.sup.M are as defined. Such a derivative of the general formula (Y) is superior in electron transferring capability. Accordingly, an electrophotosensitive material comprising a photosensitive layer containing this derivative (Y) is superior in sensitivity.

Abstract: The present invention provides a novel trinitrofluorenonimine derivative represented by the general formula (1): ##STR1## wherein R.sup.0 is an alkyl group; and R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or different and indicate a hydrogen atom, an alkyl, an alkoxy, an aryl, an aralkyl, a halogen atom or an alkyl halide. This derivative is superior in electron transferring capability and compatibility with binding resin. Accordingly, an electrophotosensitive material comprising this derivative as an electron transferring material is superior in sensitivity.

Abstract: According to the present invention, there is provided a novel tryptoanthorine derivative represented by the formula: ##STR1## wherein R.sup.1a, R.sup.1b, R.sup.1c, R.sup.1d, R.sup.2a, R.sup.2b, R.sup.2c, and R.sup.2d are the same or different and indicate a hydrogen atom, an alkyl group or a halogenated alkyl group; provided that R.sup.1a, R.sup.1b, R.sub.1c and R.sup.1d do not indicate a hydrogen atom, simultaneously. Tryptoanthorine and a derivative thereof are suitably used for an electrophotosensitive material because of their excellent electron transferring capability.