Fluoropolymer indium-tin-oxide buffer layers for improved power conversion in organic photovoltaics

We investigate the effects of polytetrafluoroethylene (PTFE) on poly (3-hexylthiophene): phenyl-C61- butyric acid methyl ester (P3HT:PCBM) based organic photovoltaic (OPV) devices by inserting thermally evaporated PTFE films between indium-tin-oxide (ITO) and P3HT: PCBM layers. Significant improvement in terms of open-circuit voltage, short-circuit current, and thereby in its commensurate power conversion efficiency is achieved compared to devices with poly (3,4-ethylenedioxythiophene): poly (styrene-sulfonate) layers. The OPVs performance enhancement is attributed to the formation of an artificial dipole layer resulting from the rich, negatively charged fluorine that facilitates the hole extraction process. This result shows the high potential of PTFE as a low cost and stable ITO buffer layer for OPV devices. (C) 2008 American Institute of Physics.