US 5,232,804 : Electrophotographic element and method of making same
An electrophotographic element comprises a single aggregate photoconductive layer which contains a continuous phase that has a high glass transition temperature Tg, of at least about 110° C. The required high glass transition temperatures can be obtained by using compositions for the aggregate photoconductive layer that contain organic charge transport agents with high glass transition temperatures or polymer binders with high glass transition temperatures, or combinations of both. In a preferred embodiment an aggregating bisphenol A polycarbonate is used in combination with a cobinder polymer that has a high glass transition temperature. The electrophotographic element of the invention can be dried at temperatures of at least about 100° C., and preferably from about 110° C. to about 145° C., to eliminate the solvent used in coating. The dried photoconductive layer exhibits good physical properties and excellent photographic performance, which remains stable with continued use.