First-principles study of defect properties in Sn-based perovskites

Sn-based halide perovskites have attracted interest for applications in solar cells due to their nontoxicity compared to Pb-based perovskites and ideal bandgaps. The power conversion efficiency, however, is limited due to the low defect tolerance and p-type self-doping. In this work, we use density functional theory (DFT) calculation to investigate defect properties in Sn-based perovskites. By calculating the defect formation energies and charge state transition levels, we identify the origin of p-type doping and propose dopants that compensate the p-type doping. We also discuss the defect origin of nonradiative recombination. Our work will provide insights and guidelines for experimental synthesizing conditions for improved device performance.