An interesting phenomenon of impurity sulfur in phthalocyanine photoreceptor device

A dual-layered photoreceptor device made from a X-form metal-free phthalocy anine (chi-H2Pc) was prepared. The effects of impurity sulfur and its chemi cal valence state in the chi-H2Pc on the properties of electrophotography h ave been studied. One of the interesting phenomena observed is the role of impurity of sulfur in chi-H2Pc is promoting the performance of photorecepto r devices. This is, the higher the sulfur impurity in chi-H2Pc, the lower t he surface residual potential on photoreceptor devices, suggesting that it would be a kind of defect assisted carrier injection from the carrier gener ation layer (CGL) into the carrier transport layer (CTL) and followed by th e trap modulated carrier transport. The photoelectron properties of a dual-layered photoreceptor device were ch aracterized by corona charging/photodischarging measurements. They are the saturated initial surface dark potential (V-0), dark decay rate DR(%) = (V- D/V-0) x 100% measured by the average potential decreases in the initial 2s after dark decay, V-D is measured after 2s dark decay, light sensitivity ( E-1/2 = E-L x t(1/2)) calculated from illuminating power (EL) and half phot odecay time (t(1/2)), and photodecay surface residual potential (V-r) after 1.5 s illumination. (C) 1999 Elsevier Science Ltd. All rights reserved.