Sublattice mixing in Cs2AgInCl6 for enhanced optical properties from first-principles

Abstract

Lead-free double perovskite materials (viz., Cs2AgInCl6) are being explored as stable and nontoxic alternatives of lead halide perovskites. In order to expand the optical response of Cs2AgInCl6 in the visible region, we report here on the stability, electronic structure, and optical properties of Cs2AgInCl6 by sublattice mixing of various elements. We have employed a hierarchical first-principles-based approach starting from density functional theory (DFT) with appropriate exchange-correlation functionals to beyond DFT methods under the framework of many body perturbation theory (viz., G0W0@HSE06). We have started with 32 primary set of combinations of metals M(I), M(II), M(III), and halogen X at Ag/In and Cl sites, respectively, where the concentration of each set is varied to build a database of nearly 140 combinations. The most suitable mixed sublattices are identified to engineer the bandgap of Cs2AgInCl6 to have its application in optoelectronic devices under visible light.