Structural, electronic and optical modeling of perovskite solar materials ASnX3 (A = Rb, K; X = Cl, Br): First principle investigations

In this paper, we present structural, electronic and optical response for inorganic lead-free tin halide perovskites ASnX(3) (A = Rb, K; X = Cl, Br) compounds, to examine their possible utilization as future photovoltaic materials. The structural optimization, energy band structure, density of states and exhaustive optical spectra for these perovskite compounds are delved using the Tran-Blaha modified Becke-Johnson exchange and correlation potential as implemented in Wien2k code. Optical performance of the compounds is accomplished through the investigation of real & imaginary dielectric tensor components, optical absorption, reflectivity and refractivity spectra. Direct band gap for RbSnCl3 (RbSnBr3) and KSnCl3 (KSnBr3) compounds is obtained as 1.46 (0.98) eV and 1.48 (0.93) eV, respectively which lies within standard photo-voltaic range. Results obtained in present computations are in decent agreement with earlier reported data, which firmly endorse the accuracy of present calculations. In addition, band gap reduction is perceived while switching from X = 'Cl' to 'Br' which has also revealed the enhancement in integrated absorption coefficient. Promising electronic and optical properties obtained for these perovskite compounds affirms their potential utilization in photo-voltaic and other optoelectronic applications.