Strain effects on electronic, optical properties and carriers mobility of Cs2SnI6 vacancy‐ordered double perovskite: A promising photovoltaic material

Abstract Perovskite halides have attracted substantial attention as materials for solar cell applications because of their fascinating optoelectronic and photovoltaic properties. We report the results of the first‐principles calculations of the strain effects on electronic and optical properties and carrier mobility of vacancy‐ordered Cs 2 SnI 6 double perovskite. The calculated band gap energy of unstrained Cs 2 SnI 6 is about 1.257 eV when using the Tran‐Blaha modified Becke Johnson (mBJ) exchange potential, which is in good agreement with experimental measurements. Under the applied strains, the energy band gap value increases up to 1.316 eV for −4% compressive strain and decreases to 1.211 eV for 4% tensile strain. This effect is mainly due to the fact that the conduction band minimum shifts under compressive and tensile strains. Based on carrier mobility calculations, we notice that under tensile strain the hole and electron carrier mobility diminish, whereas the carrier mobility increases by 16.3% for electrons and by 9.1% for holes under −4% compressive strain. Moreover, data of the calculated optical constants indicate that applied strains can affect the optical properties of Cs 2 SnI 6 perovskite.