Strain-induced tunability of the optoelectronic properties of inorganic lead iodide perovskites APbI3 (A= Rb and Cs)

Herein we investigate the influence of biaxial strain ranges from −2% to +2% on the optoelectronic properties of APbI3 (A = Rb and Cs) perovskites through first-principles density functional theory calculations. It has been explored that the biaxial strain in APbI3 (A = Rb and Cs) can significantly increase their absorbance, both in the visible and ultraviolet light energy range. The electronic band structure shows that the RbPbI3 and CsPbI3 compounds are all semiconductors with a direct bandgap of 1.05 eV and 1.28 eV, respectively, at the R-point. However, the bandgap of APbI3 (A = Rb and Cs) reveals a decreasing trend and has a tendency towards the metallic condition when the compressive strain is applied. Besides, due to the increase of tensile strain, the bandgap of APbI3 exhibits an increasing trend. Therefore, this study would provide a systematic way to satisfy the requirements of different optoelectronic device applications through biaxial strain.