▎ 摘　　要

We report the enhanced photovoltaic properties in polycrystalline BiFeO3 (BFO) thin films with graphene as top electrodes. The short circuit current density (J(sc)) and open circuit voltage of the heterojunction are measured to be 25 mu A/cm(2) and 0.44 V, respectively, much higher than the reported values for polycrystalline BFO with indium tin oxide (ITO) as top electrodes. Influence of HNO3 treatment on the photovoltaic properties is studied, and a significant photocurrent density improvement from 25 mu A/cm(2) to 2.8 mA/cm(2) is observed. A metal-intrinsic semiconductor-metal model is proposed to explain the graphene induced enhancement comparing with traditional ITO. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3644134]