Ab-initio calculation of electronic properties of all-inorganic Pb-based mixed-halide perovskites

Mixed lead-halide perovskite films have recently become a subject of intensive study in the nanophotonic community due to their unique optical properties. In this work we present theoretical investigations of the electronic band structure of full inorganic mixed-halide perovskites in a continuous range of chemical compositions. We demonstrate that in the orthorhombic geometry independently on the particular halogen concentrations the optical band gap remains direct, varying in the absolute value, with the fundamental absorption edge corresponding to the high symmetry point Γ of the band structure. This tunability of the optical band gap in inorganic mixed-halide perovskites is highly promising and has various possible nanophotonic and photovoltaic applications.