Enhanced stability and optoelectronic properties of double perovskite Cs2AgSbI6 by Br doping for solar cells

Abstract

Lead halide perovskite photovoltaic cells offer much higher energy conversion efficiency. However, new non-toxic semiconductor compounds are being sought due to instability and lead toxicity. The stable double perovskite Cs2AgSbI6 is the base material for this investigation since it has been demonstrated to be an effective and ecologically replacement for lead halide perovskites. In this study, the cubic space phase of the bromine alloy double inorganic halide perovskite Cs2AgSb(I1−xBrx)6 was analyzed using density functional theory (DFT). The band gap was widened with increasing percentages of Br doping, and theoretical calculations were used to determine the best structures for these compounds. Theoretically, its optoelectronic characteristics are computed using the GGA-PBE and GGA-TB-mBJ approximations. We found that Cs2AgSb(I1−xBrx)6 is stable under typical conditions with a band gap below 2 eV. Thus, it is advised to utilize Cs2AgSb(I1−xBrx)6 for solar cell applications. The spectroscopic limited maximum efficiency (SLME) technique was used to analyze theoretical efficiency (η), with the gap energy, absorption coefficient, and absorption estimated from the typical AM1.5G solar spectrum at 25 °C serving as key input factors. We attained an η of 18 % for Cs2AgSb(I0.50Br0.50)6 at a thickness of 800 nm.