Efficient photogeneration of charge carriers in a layered photoreceptor using a conjugated polymer

The field-dependent quantum efficiency φ(E) for photogeneration of charge carriers in a bilayer photoreceptor consisting of a poly(p-phenylene benzobisthiazole) charge generation layer and a hole transporting layer has been measured by the xerographic photodischarge technique. φ(E) varied from 0.10 at low fields (<105 V/cm) to 0.32 at 106 V/cm. The conjugated polymer-based photoreceptors have a photosensitivity of 13 ergs/cm2 and negligible dark decay (∼0.2 V/s). Photocarrier generation in the bilayer devices is suggested to be due to field-assisted dissociation of exciplexes formed between the conjugated polymer and the hole transporting molecule.