Tuning the electronic dimensionality and bandgap in CsAgBiX (X = Br, Cl) for photovoltaic applications: a DFT-1/2 study of cation disorder.

Nontoxic, stable, and experimentally realized lead-free halide double perovskites, CsAgBiX (X = Br, Cl), attracted much attention for solar cell applications. However, their reduced electronic dimensionality and indirect (wide) bandgap, limiting solar energy absorption efficiency, are not mostly suitable. To address such issues, we employ the computationally efficient DFT-1/2 + SOC method to study the electronic structure of cation-ordered and cation-disordered materials comparatively.