Multiferroic BiFeO₃ materials have driven great interest due to their potential in solar-spectrum energy harvesting, optoelectronic and photodetection devices. Here we report effects of electric-field poling on electronic hybridization and domain structure, and their correlations with photovoltaic responses in the ITO/(Bi_0.93Gd_0.07)FeO₃ ceramic/Au heterostructure under 405 nm and 532 nm irradiations. Photovoltaic conversion, photoresponsivity (R) and specific detectivity (D*) are sensitive to ceramic thickness, photon energy, light intensity and electric-field poling. The photoresponsivity and detectivity in the 1 kV/cm poled photovoltaic cell under low-intensity 405 nm irradiation can respectively reach ∼4.5 × 10⁻² A/W and 2.5 × 10¹¹ Jones, which are larger than ∼2.8 × 10⁻² A/W and 1.56 × 10¹¹ Jones in the unpoled cell. This study demonstrates fast response times of ∼1 × 10⁻³ s and ∼2 × 10^-2 s respectively under 405 nm and 532 nm irradiations. The improved photoresponse was driven jointly by the p-n junction, the field-modulated Schottky barriers and the network of grain boundaries and domain walls.[ Link to this article]

Keywords Photovoltaic conversion Polar nano-region Domain wall Photoresponsivity Specific detectivity Response time