(698a) Computational Search for Halide Double Perovskite Optoelectronics

This talk will discuss our recent search for inorganic double perovskites (A2BB’X6) with Cs on the A-site, Cl on the X-site, and a variety of cations occupying the two B-sites. We applied a tiered screening approach, starting with our recently introduced tolerance factor for perovskite stability, moving to density functional theory (DFT) to further support the stability of predicted candidates, and concluding with “beyond” DFT approaches (GW-BSE) to understand the excitonic properties of a select subset of predicted materials. We found that materials having a mixture of alkali (e.g., Na, K) and transition metal (e.g., Mn, Ni) cations on the B-site have promising thermodynamic stabilities, small band gaps, and unusual electronic structures leading to exceptionally large exciton binding energies. The origins of the stability and electronic structure of these materials were understood using crystal orbital Hamilton population (COHP) analysis to assess the bonding in these and related materials. In addition to searching for new stable materials, we also assessed practical considerations for calculating the properties of perovskite semiconductors (e.g., improving stability and band gap predictions by accounting for structural distortions).