Ultra-high efficiency, stability and low-cost perovskite solar cell materials [formula omitted] for photovoltaic applications: First principles prediction

Abstract

Photovoltaic cells composed of lead-halide perovskites have shown a remarkable increase in energy conversion efficiency. However, they face instability problems which, combined with lead toxicity, have led to the search for new non-toxic semiconductor compounds. In this study, we start from a stable double perovskite, Cs2 ZrI6, which has emerged as an effective and environmentally friendly alternative to lead halide perovskites. Based on the first principles calculations, we find that the band gap decreases with increasing Ti4+ doping content. Our calculated results show that these alloys materials exhibit good structural stability and a suitable band gap (1.17 <Eg < 2.33 eV). In addition, the estimation of the theoretical efficiency was investigated by the Spectroscopic Limited Maximum Efficiency (SLME) method, in which the gap energy, absorption coefficient and absorption calculated from the standard AM1.5G solar spectrum at 25 °C are the important input parameters. We observe several high efficiencies. For Cs2Zr0.75Ti0.25I6(x=0.25), we obtain an SLME (η) of 32.96% at a thickness of 500 nm. Moreover, the obtained results show that compounds (for x=0.25, 0.50, 0.75, 1.00) are promising candidates for perovskite solar cells.