Stabilizing orthorhombic CsSnI3 perovskites with optimized electronic properties by surface ligands with inter-molecular hydrogen bond

Currently, the exploration of green tin halide perovskite solar cells (PSCs) based on orthorhombic (γ-) CsSnI3 is fundamentally hindered by its intrinsic bad stability. Herein, based on the first principles calculation, three surface-ligand-passivated configurations having inter-molecular hydrogen bonds are rationally designed and investigated for stabilizing γ-CsSnI3. It is discovered that the inter-molecular hydrogen bond could suppress the distortions of both ligands and the octahedral of perovskites, thus favoring improvement in the stability of γ-CsSnI3, which is closely related to bond strength. Moreover, the existing inter-molecular hydrogen bond could limit the localization of charge density, which helps promote electron transition and mobility with optimized carrier effective masses, thus favoring an enhanced performance of γ-CsSnI3 PSCs. The present work might give some insight on pushing forward the strategy of surface ligand passivation for engineering stabilized γ-CsSnI3 PSCs with high efficiency.