Interface modification of polymer solar cells using graphene oxide and TiO2 NPs

The photovoltaic behavior and stability of P3HT:PCBM bulk heterojunction polymer solar cells (PSCs) were studied in detail, in which graphene oxide (GO) and TiO2 nanocrystalline particles (TiO2 NPs) were used as hole transport layer (HTL) and electron transport layer (ETL), respectively. The power conversion efficiency (PCE) of PSC deviceswith the GO as the HTL reached 3.09%, which is comparable to those using the PEDOT: PSS as the HTL. The PCE was further improved by using TiO2 NPs buffer layer as the ETL and reached 3.32%. The interface capacitance analysis and electrochemical impedance measurement confirmed that the GO as the HTL in PSCs has better interface properties than the PEDOT: PSS. The device stability showed that PSCs with the GO layer are much more stable than those with the PEDOT: PSS layer. The PCEs of PSC devices with both GO and TiO2 NPs layers could retain 60% of its initial value after 180 h exposure in high humidity atmospheric environment (air humidity similar to 80%). The study showed that the combination of GO and TiO2 NPs acted as the HTL and ETL, respectively, has the potentials for preparing efficient and stable PSCs devices, which can match with the printing or coating techniques. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim