Investigations of charging and discharge in the dark of organic electrographic photoreceptors

This work deals with physical processes that occur in organic electrophotographic photoreceptors (OEP) formed of charge photogeneration layer (CGL), charge transport layer (CTL) and barrier layers during their dosed charging and discharge in the dark. It has been found that there are no detectable charge carrier injection–extraction processes in CTL during its dosed charging and space charge does not form in it. However, during the dosed charging of OEP, when potential exceeds 50–60 V, an intense injection of holes from CGL into CTL begins. At lower potential values, the geometric capacitance of the OEP is only charged. Hole density in the CGL reservoir depends on the initial exposure to white or red (780 nm) light and exceeds (6–10)×1011 cm2. Discharge in the dark of positively charged OEP is caused by hole injection from deep levels existing in CGL and from surface levels of OEP. Activation energy of these levels decreases with the initial charging potential.