New buffer interlayer for improving device performances of organic small molecule solar cells

We investigate the effects of polytetrafluoroethylene (PTFE) on organic photovoltaic (OPV) devices with structure of ITO/PTFE/ poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS)/copper phthalocyanine(CuPc)/C 60 / bathocuproine(BCP)/Al by inserting thermally evaporated PTFE films between indium-tin-oxide (ITO) and PEDOT:PSS 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 PEDOT:PSS 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.