Pb-free perovskite solar cells composed of Sn/Ge(1:1) alloyed perovskite layer prepared by spin-coating

Abstract Since the DMSO seriously oxidizes the GeI 2 which is one of the ingredients for the Sn/Ge perovskite, it was difficult to make high-quality films by using the conventional DMSO/DMF solvent. We now first report the MASn 0.5 Ge 0.5 I 3 perovskite solar cells (PSCs) prepared by a simple spin-coating technology. We found that triethanolamine (TEA)/n-methyl pyrrolidone (NMP) does not oxidize the GeI 2 and improves the stability of the precursor. The precursor solution with TEA/NMP/DMF gave high-quality perovskite films. The cell gave a power conversion efficiency of 2.18%. This is the first report proving that Sn/Ge PSCs are fabricated by a conventional solution process.