Efficiency enhancement of inverted organic photovoltaic devices with ZnO nanopillars fabricated on FTO glass substrates

ZnO nanopillars are grown on a ZnO seed layer on fluorine-doped tin oxide (FTO)-coated glass substrates for the fabrication of inverted organic photovoltaic devices based on poly(3-hexylthiophene) and (6,6)-phenyl C61-butyric acid methyl ester. It is found that the oriented ZnO nanopillars play an important role in collecting photogenerated electrons and act as an electron-transport path to the cathode. OPV devices with a ZnO nanopillar layer grown on a ZnO seed layer exhibit a threefold increase in power conversion efficiency compared with that of devices with a ZnO seed layer only.