Photocarrier generation and injection at the interface in double-layered organic photoconductors

Abstract

Photocarrier generation and injection processes in double-layered organic photoconductors consisting of carrier generation layer (CGL) and carrier transport layer (CTL) were studied by means of photoacoustic and xerographic time-of-flight methods. In the photoacoustic method, the photocarrier generation efficiency in the CGL was derived by measuring the decrease in photoacoustic signal due to carrier recombination in the CGL. On the other hand, in the xerographic method, the ratio of the number of holes emitted into the CTL to that of absorbed photons in the CGL was obtained from the temporal change in surface voltage under light pulse irradiation. From comparing two experimental results, we evaluated the injection efficiency of holes at the CGL/CTL interface. The injection efficiency is determined by the trapping of holes at the CGL/CTL interface.