Tuning the optoelectronic and thermoelectric properties of vacancy-ordered halide perovskites Cs2Ge(1-x)PtxCl6 (x=0, 0.25, 0.50, 0.75 and 1.00) via substitutional doping of Pt using first-principles approach

Abstract

Vacancy-ordered halide perovskites have gained considerable attention from researchers regarding non-traditional energy harvesting applications like solar cells and thermoelectric generators. However, in most of the reported cases, band gaps are larger (>3.5eV) consequently the efficiency of solar cells and thermoelectric generators becomes low. Currently, we studied non-toxic and stable vacancy-ordered halide perovskites Cs2GeCl6 and tuned its band gap via substitutional doping of Pt (0, 25, 50, 75, and 100 %) using the first-principles approach. The band gap engineering strategy of Pt doping effectively decreased the band gaps (up to 2.50eV) hence, the more attractive optical and thermoelectric parameters are obtained for instance; high absorption coefficients (similar to 10(5) cm(-1)), low reflectivity (similar to 0.3-10 %), high optical conductivity (similar to 10(15) sec(-1)), and large figure of merits (similar to 1). Based on these enhanced optical and thermoelectric performance parameters, the Pt doping strategy can be taken as an effective practice to tune the band gap significantly in order to stimulate the performance of future solar cells and thermoelectric generators.