Electrophotographic selenium photoreceptor

摘要

In order to increase the life, measured in the number of printable copies, of an electrophotographic selenium photoreceptor used in an optical printer or a copying machine, the receptor has a coating layer as the outer layer of a laminate comprising a conductive base, a charge-carrier transport layer comprising amorphous selenium or an amorphous Se/Te alloy, a charge-carrier production layer comprising an amorphous Se/Te alloy containing from 20 to 50% by weight of tellurium, and the coating layer. The life of the coating layer is extended by increasing the As concentration in the outer coating layer. Greatly differing coefficients of thermal expansion between the charge-carrier production layer and the coating layer mean that cracking can occur. In order to prevent this and simultaneously to extend the life of the photoreceptor, the outer coating layer is in the form of a two-layer structure, where the inner or lower layer adjacent to the charge-carrier production layer has a lower arsenic content than the outer surface layer, the thickness of the outer surface layer being greater than that of the lower layer and being not more than 8 mu m.