Thermally stimulated currentmeasurements on the trapping levels in a Cu-phthalocyanine binder photoreceptor

Abstract

Thermally-stimulated current (TSC) is measured in a Cu-phthalocyanine binder photoreceptor. The Cu-phthalocyanine powder used has an ε-type crystal form. The binder is polyurethane. It is found that the measured TSC curves have peaks due to thermal liberation from the hole trapping levels and that the peak TSC temperature has an electric field dependence. The following results are obtained from an analysis of these TSC curves: (1) The origin of the trapping levels is the interface between Cu-phthalocyanine particles and the insulating binder. (2) The activation energy Ea of the hole trapping levels has an electric field dependence, Ea = 0.45−0.59×10−3E1/2 eV, where the unit of E is V/cm. This dependence is explained by the Poole-Frenkel theory.