Studies of injection and transport in polymeric media: the connection to key issues in electrophotographic technology

Trap free, flexible but robust glassy polymeric coatings which can efficiently transport injected charge were developed to support the commercialization of large area organic photoreceptors (OPC) required for a variety of electrophotograpic printers and publishing engines. The drive toward specific optimization of these materials systems for xerography stimulated scientific research and then directly benefited from it. Molecularly doped polymers (MPD) whose chemical content and morphology are engineered have in particular provided an extraordinarily "transparent" laboratory for the study of hopping transport, trapping, and injection phenomena. Starting with these molecularly doped polymers a convoluted pattern of common features has been identified in the drift mobility behavior of a wide variety of disordered molecular media including conjugated polymers. As a result, theoretical work has been impelled to focus on their shared characteristics, disorder and the possibility of site relaxation as the mechanisms likely to dominate charge motion. The fact that in response to the requirements of xerography these transport media could be made trap free by employing molecular design principles provided in turn, a unique venue for the exploration of contact behavior on disordered organic solids. (C) 2003 Elsevier B.V. All rights reserved.