Effect of chlorine vacancy on the electronic and optical properties of CsSnCl3 perovskites for optoelectronic applications

In this work, we use the density functional theory (DFT)-based first-principal calculations to simulate geometric structures, electronic properties, and molecular dynamics (MD) of all inorganic CsSnCl3 perovskites without and with containing a chlorine vacancy. Our results demonstrate that the introduction of a Cl vacancy induces trap state and narrows the bandgap. The overlap between trap state and conduction band minimum (CBM) is large due to their similar chemical nature. Besides, the introduction of a Cl vacancy perturbs the Sn-Cl lattice vibration and corresponding phonon modes. Defective perovskite shows higher absorption than pristine perovskite owing to the narrower band gap.