First-principles investigations on the structural and optoelectronic properties of lead-free perovskite Mn:CsSnX3

Nontoxic metal halide perovskites have become a research hotspot in the field of solar cells and other optoelectronic devices. However, low power conversion efficiency owing to their instability limits their wide practical applications. Herein, the structural stability and optoelectronic properties of 12.5% Mn-doped CsSnX3 (X = I, Br, and Cl) perovskite systems were investigated via first-principles computations. The investigations of the formation energy and mechanical parameters indicated that Mn-doping improved the structural stability. As for electronic properties, the band structures of CsSnX3 changed from direct to indirect bandgap after Mn-doping because of the modulation of the crystal field between ions caused by the substitution of Sn ions with Mn ions. The optical properties of the CsSn0.875Mn0.125X3 perovskite were studied, including absorption coefficient, extinction coefficient, reflectivity, and refractive coefficient. The results of this work provide theoretical support for the design of next-generation lead-free and low-toxicity optoelectronic and photovoltaic materials and devices.