High voltage hybrid organic photovoltaics using a zinc oxide acceptor and a subphthalocyanine donorElectronic supplementary information (ESI) available: XPS survey scan and C 1s of the ZnO thin film processed at 120 °C and 160 °C. See DOI: 10.1039/c4cp02733g

We demonstrate hybrid organic photovoltaic (HOPV) bilayer devices with very high open circuit voltages ( V OC ) of 1.18 V based on a sol-gel processed zinc oxide (ZnO) acceptor and a vacuum deposited boron subphthalocyanine chloride (SubPc) donor layer. X-ray photoelectron spectroscopy (XPS) and Kelvin Probe (KP) measurements of the ZnO/SubPc interface show that the ZnO preparation conditions have a significant impact on the film composition and the electronic properties of the interface, in particular the work function and interface gap energy. Low temperature processing at 120 °C resulted in a ZnO work function of 3.20 eV and the highest V OC of 1.18 V, a consequence of the increased interface gap energy. The voltage of ZnO/SubPc hybrid devices was enhanced to 1.18 eV by optimising the ZnO thin film processing conditions