First-principles study of aziridinium tin iodide perovskites for photovoltaics

Abstract

Solar cells with organic–inorganic lead halide perovskites have attracted great attention in the last decade. Herein, we propose lead-free halide perovskite (CH₂)₂NH₂SnI₃, as well as alloys (CH₂)₂NH₂SnI_3−xBr_x, to avoid the toxicology of lead element. We find that the perovskite (CH₂)₂NH₂SnI₃ has much better stability than CH₃NH₃PbI₃ and possesses a band gap of 1.06 eV. Meanwhile, the alloy (CH₂)₂NH₂SnI₂Br has an ideal band gap of 1.31 eV for photovoltaics. The alloy (CH₂)₂NH₂SnI_3−xBr_x is proved to have higher optical absorption than CH₃NH₃PbI₃ in general. We thus propose that the lead-free perovskite (CH₂)₂NH₂SnI₃ and alloys (CH₂)₂NH₂SnI_3−xBr_x are probably excellent candidates for stable and high-performance photovoltaic absorber materials.