Pressure-Induced Topological Nontrivial Phase and Tunable Optical Properties in All-Inorganic Halide Perovskites

Cesium-based all-inorganic halide perovskites CsMX3 (M = Pb, Sn; X = Cl, Br, I) have been considered as important candidates for highly-efficient, chemically stable optoelectronic devices and solar cells. Pressure can serve as an effective and clean thermodynamic approach to better performance of CsMX3. In this work, we use first-principles density functional theory calculations with both Perdew–Burke–Ernzerhof and GW + Bethe–Salpeter equation to systematically study the effects of pressure on the electronic structures, carrier transport, and optical properties of cubic phase CsMX3. Our results show that with increasing hydrostatic pressure, the optical band gap red-shifts until the pressure reaches a critical value, above which the band inversion is observed due to the spin–orbit coupling. The resulting nontrivial topological gap blue-shifts with further increasing pressure. This work provides insights into the rational design of experiments to engineer the properties of CsMX3 perovskites by applying pressure.