Bulk and domain-wall effects in ferroelectric photovoltaics

Abstract

We investigate the photovoltaic (PV) effects in ferroelectrics based on the polar structure in domains and the intrinsic symmetry breaking of ferroelastic domain walls (DWs). A comprehensive analysis for $\mathrm{BiFe}{\mathrm{O}}_{3}$ films with the single-domain and 71\ifmmode^\circ\else\textdegree\fi{} domain structures reveals a major contribution of the DWs superimposed on the bulk PV effect, which can explain the enhanced PV response in the multidomain film exhibiting photovoltages greater than the band gap. Our methodology can reveal the contributions of the bulk PV and the DW-PV effects quantitatively and uncover a design strategy for enhancing ferroelectric photovoltaics.