ABSTRACT
I. INTRODUCTION Xerographic photoreceptors are usually prepared in a dual-layer arrangement. In this configuration, the photogeneration of free carriers occurs in the generation layer, or at the interface between the generation and transport layers. Either electrons or holes are injected into the transport layer where they are displaced to the free surface or the substrate electrode. A fundamental requirement of the transport layer is that the mobility must be such that charge can transit the layer thickness in a time that is short compared to the time between the exposure and image development steps. A further requirement is that the transport occur in the absence of deep trapping over an extended range of fields. Polymers are widely used for transport layers. For this reason, charge transport phenomena in these materials are of considerable importance to xerography.
