Candidate replacements for lead in CH3NH3PbI3 from first principles calculations

Due to its toxicity, there is a compelling need to replace lead in the organic-inorganic hybrid perovskite CH3NH3PbI3, a high-performance photovoltaic material. We use density functional theory (DFT) calculations with the generalized gradient functional PBEsol, the meta-GGA functional SCAN, and the hybrid functional HSE06, including spin-orbit coupling, to screen substituent elements based on their fundamental bandgap. Of the 27 candidate elements explored, we identify six (Mg, Si, Ge, Cd, Hg, and Zn) to be viable candidates for replacing Pb in the hybrid perovskites. We further characterize the optical absorption spectrum, with and without spin-orbit coupling, for these candidate replacements.