Inorganic photovoltaic cells based on BiFeO3: spontaneous, element substitution, lattice matching, light polarization and their relationship to photovoltaic performance

Inorganic ferroelectric perovskite oxides are more stable than hybrid perovskites. However, their solar energy harvest efficiency is not so good. Here, by fabricating a serious of BiFeO3 based devices, we investigated four factors that influence the photovoltaic performance, including spontaneous polarization, mechanism of leakage current suppression by Co element substitution, terminated atoms species in the heterogeneous structure with the electrode, and polarized light irradiation with the framework of density functional theory combined with non-equilibrium Green's function theory under built in electric field or finite bias. The results showed that 1)the photocurrent is larger only under a suitable electronic band gap rather than larger spontaneous polarization; 2) the BiFeO3 based solar cell degradation could be suppressed by Co element substitution due to the dark current suppression; 3) the photocurrent reaches the largest in Bi ions terminated interface than the case of Fe or O with SrTiO3 devices; 4) the power conversion efficiency could be largely enhanced if the polarized direction of the monochromatic light is perpendicular to the spontaneous polarization direction. The results will deepen the understanding of experimental results of BiFeO3 based solar cells.