Photocarrier generation site in a layered photoreceptor based on azo pigment: Effect of wet-coated formations

Abstract

The structures of interfaces between a carrier generation layer (CGL) and a carrier transport layer (CTL) which are considered to be a photocarrier generation site in a layered photoreceptor have been analyzed. It was found that the thickness of the CGL, which consists of the fluorenone-based bisazo pigment (CGM) and binder resin, was expanded about 1.5 times after the CTL was deposited by a wet-coating process. A substantial amount of the carrier transport material (CTM) had penetrated preferentially into the CGL from the CTL to the binder resin, remaining as the CTL dried out. The photocarrier generation site in such a layered photoreceptor is found not to be a planar CGL/CTL interface but a three-dimensional CGM/CTM interface spread out over the bulk of the CGL. The CTM:CGM ratio in the CGL of the layered photoreceptor is estimated to be 0.8–0.95:1 in weight. It is also considered that the number of the photocarrier generation sites originated by the CTMs in the CGL was close to the number needed to saturate the rising function of charge carrier quantum yield ΦET with rising CTM/CGM in the nominal CGL.