Photovoltaic effects in $BiFeO3$

We report a photovoltaic effect in ferroelectric $BiFeO3$ thin films. The all-oxide heterostructures with $SrRuO3$ bottom and tin doped indium oxide top electrodes are characterized by open-circuit voltages $∼0.8–0.9V$ and external quantum efficiencies up to $∼10%$ when illuminated with the appropriate light. Efficiencies are at least an order of magnitude larger than the maximum efficiency under sunlight (AM 1.5) thus far reported for ferroelectric-based devices. The dependence of the measured open-circuit voltage on film thickness suggests contributions to the large open-circuit voltage from both the ferroelectric polarization and band offsets at the $BiFeO3/tin$ doped indium oxide interface.