Effect of hole transporting layers on the performance of PCPDTBT:PCBM organic solar cells

Abstract

We study the performance of PCPDTBT:C 71-PCBM organic photovoltaics (OPVs) for three hole transporting layers (HTL); PEDOT:PSS, nickel oxide (NiO) and molybdenum trioxide (MoO 3). We show that devices fabricated with nickel oxide HTL demonstrate the highest power conversion efficiency and theoretical data using a transfer matrix model confirms that this is as a result of increased absorption in the active layer as well as a result of improved series resistance and improved matching of energy levels. Device degradation is studied and lifetime is highest for the NiO and MoO 3 based devices, proving that OPVs with this material system are less sensitive to the environmental effects of water, oxygen and irradiance. © 2012 IOP Publishing Ltd.