Photovoltaic, photo-impedance, and photo-capacitance effects of the flexible (111) BiFeO_3 film

摘要

Ferroelectric polarization allows a depolarization electric field to separate electron-hole pairs excited by lights, and thus, the photovoltaic properties of ABO(3)-type films on a hard SrTiO3 or Si substrate have been extensively studied recently. However, there are a few reports on the photocapacitance and photoimpedance of these oxide films, especially on flexible substrates. In this work, the strong photovoltaic, giant photocapacitance, and photoimpedance effects were observed in the flexible (111) BiFeO3 films with natural downward polarization. The flexible mica/SrRuO3/BiFeO3/Au cells show a maximum photovoltaic efficiency at 150 degrees C, a 95.5% decrease in photoimpedance effects, and a 316% increase in photocapacitance effects under 405-nm-wavelength light illumination at 25 degrees C. Most importantly, these properties do not show obvious degradation when the device is bent to 3 mm radius for 10(4) times. This work is of vital importance for us to develop new flexible photoelectronic devices.