The Ionization Potential of Carrier Transport Materials in Relation to the Photosensitivity of Double Layered Photoreceptors

Double layered photoreceptors using low ionization potential molecules as the carrier transport layer (CTL) have been investigated. The ionization potential (lp) was estimated by the ¿ technique calculation and the polarographic oxidation potential. A good correlation was obtained between the photosensitivity and the lp value of the CTL. However this result could not be explained simply by the energy level misfit of the carrier generation layer (CGL) and the CTL. Styryl dye bases, cyanine dye bases, and oxazoles were selected as CTL materials on the basis of their transparency and high solubility in polymers. The photoreceptors using these CTL materials showed much higher sensitivities than the well-known polyvinylcarbazole- trinitrofluorenone (PVK-TNF) system. The peak value of the spectral sensitivity in the system composed of an oxazole, OX-2, and a disazo pigment, chlorodianeblue (CDB), was 0.17 m 2/mJ at 650 nm.