Improved exciton dissociation at semiconducting polymer:ZnO donor:acceptor interfaces via nitrogen doping of ZnO

Abstract

Exciton dissociation at the zinc oxide/poly(3-hexylthiophene) (ZnO/P3HT) interface as a function of nitrogen doping of the zinc oxide, which decreases the electron concentration from approximately 1019 cm-3 to 1017 cm-3, is reported. Exciton dissociation and device photocurrent are strongly improved with nitrogen doping. This improved dissociation of excitons in the conjugated polymer is found to result from enhanced light-induced de-trapping of electrons from the surface of the nitrogen-doped ZnO. The ability to improve the surface properties of ZnO by introducing a simple nitrogen dopant has general applicability. Nitrogen doping of ZnO is shown to dramatically improve exciton dissociation at the interface between ZnO and a conjugated polymer. The improvements in exciton dissociation and device photocurrent follow from a reduction in the ZnO electron concentration and enhanced light-induced de-trapping of electrons from the surface of the nitrogen-doped ZnO. © 2014 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.