Thermally stimulated current studies of hole transport in a layered organic photoconductor

Thermally stimulated current (TSC) measurements have been peformed on a layered organic photoconductor based on p-diethylaminobenzaldehyde diphenylhydrazone (DEH) dispersed in bisphenol A polycarbonate. Well-defined transient current peaks were observed, indicative of a hole transport process having an activation energy of ∼0.5 eV at an applied electric field of 10 V/μm. This TSC feature is attributed to carriers which are thermally activated from electron donor states associated with the DEH molecules responsible for transport in this medium. This transport peak is clearly distinguished from the higher temperature secondary structure which is attributed to trap states. Measurements of the steady-state photoconductivity over a range of temperatures also yield approximately the same activation energy for the transport process.