Quasiparticle band structures of halide double perovskites using Wannier-localized optimally tuned screened range separated hybrid functionals

Halide double perovskites are a promising new class of materials that offer an alternative to lead halide perovskites as suitable materials to use for solar cell applications, due to their greater stability and reduced susceptibility to environmental factors. Previous calculations of the band gaps using semilocal density functionals and the GW approximation, in conjunction with the lack of experimental data available for these class of materials, has left room for ambiguity in predicting the correct fundamental band gaps of these systems. Here we use the new state of the art, Wannier-localized optimally tuned screened range separated hybrid (WOT-SRSH) functional which has recently been shown to be a promising approach for a range of standard semiconductors, insulators, and lead halide perovskites. We compare and discuss the band gaps, band structures, and optical absorption spectra for double perovskites we obtain with this method with ab initio many-body perturbation theory, prior calculations, and experiment. We also discuss the use of WOT-SRSH on other indirect gap materials.