Nanoscale Size Effects on Photoconductivity of Semiconducting Polymer Thin Films

摘要

Spatial confinement effects in semiconducting polymers were investigated by meansof photoconductivity experiments on bilayer photoreceptors consisting of a conjugated poly(2,5-pyridylene benzobisthiazole) charge generation layer and a trap-free tris(p-tolyl)amine doped polycarbonate charge transporting layer. A threefold increase in quantum efficiency for photogeneration and an enhancement of photosensitivity were observed when the semiconducting polymer layer thickness was reduced from approx. 100 to approx. 10 nm. The observed nanoscale confinement effects on photoconductivity are related to the generally small exciton diffusion lengths (5-20 nm) in semiconducting polymers and the interfacial nature of the charge photogeneration process in the bilayers.