Enhanced photovoltaic properties in graphene/polycrystalline BiFeO 3 /Pt heterojunction structure

We report the enhanced photovoltaic properties in polycrystalline BiFeO 3 (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 μ A/cm 2 and 0.44V, respectively, much higher than the reported values for polycrystalline BFO with indium tin oxide (ITO) as top electrodes. Influence of HNO 3 treatment on the photovoltaic properties is studied, and a significant photocurrent density improvement from 25 μ 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.