ENERGY-GAP DEPENDENCE OF THE PHOTOCARRIER GENERATION EFFICIENCY IN LAYERED ORGANIC PHOTORECEPTORS

The photocarrier generation mechanism was studied in layered-type organic photoreceptors containing triphenylamine-based trisazo pigment in the carrier generation layer (CGL). The photocarrier generation efficiency strongly depended upon a series of NN-diphenyl-4-biphenylamine derivatives utilized in the carrier transport layer (CTL). The dependence was successfully elucidated by means of the energy gap law using the energy gap of the electrochemical oxidation-potential difference between the azo pigment and the N,N-diphenyl-4-biphenylamine derivatives. This confirms that photocarrier generation occurs at the CGL/CTL interface and is based on photoinduced electron transfer. The reorganization energy originated in the solid system and the extent of adiabaticity of the reaction are discussed.