Abstract
We study theoretically the origin of photoconductivity in conjugated polymers. The charge carriers are released when excitons dissociate through the deep levels within the semiconductor bandgap caused by either oxidation (carbonyl group) or structure defects. Our results explain the recent observations of the temperature-independent photocurrent in the sweep-out regime and the transient photocurrent at high excitation. The tightly bound exciton versus semiconductor band controversy on the photocarrier generation process is clarified. ©2000 The American Physical Society.