First-principles investigation on the stability and material properties of all-inorganic cesium lead iodide perovskites CsPbI3 polymorphs

Cesium metal halide perovskites are very promising light absorbing materials for solar cells, due to their good thermal stability compared to other organometallic perovskites. Cesium lead iodide perovskite CsPbI3 is one the most promising compound from this family because of its band gap of 1.7eV suitable for a top cell in silicon tandem solar cell. Herein, we systematically investigate the structural, electronic, elastic, optical properties and some carrier transport properties of CsPbI3 perovskites polymorphs using pseudo-potential plane wave method implemented in CASTEP and ABINIT codes. We use hybrid functional within the GW approximation (GW-HSE06) and the spin-orbit coupling (GGA-PBE + SOC) to estimate the band gaps. The elastic properties indicate the flexibility and softness of CsPbI3 perovskites, they also have a high absorption coefficient values (alpha = 10(4)-10(5) cm(-1)) and low exciton binding energy which make them potential candidate for solar cells application.