Enhanced carrier photogeneration by defects in conjugated polymers and its mechanism

Abstract

Upon irradiating poly(p-phenylene vinylene) thin films with white light in air (total exposure ∼5 J/${\mathrm{cm}}^2$), an enhancement of about forty times in photocarrier generation and a similar reduction in the photoluminescence intensity are observed. The wavelength and electric-field dependence of the photoconductivity are, however, essentially unchanged. These results demonstrate the sensitivity of the conjugated polymers to photo-oxidation and the importance of extrinsic photogeneration processes in these materials. The microscopic physics of carrier generation and luminescence quenching are established, and we discuss the implications for various conjugated polymer devices.