Realizing Full Coverage of Stable Perovskite Film by Modified Anti-Solvent Process

Lead-free solution-processed solid-state photovoltaic devices based on formamidinium tin triiodide (FASnI(3)) and cesium tin triiodide (CsSnI(3)) perovskite semiconductor as the light harvester are reported. In this letter, we used solvent engineering and anti-solvent dripping method to fabricate perovskite films. SnCl(2) was used as an inhibitor of Sn(4+) in FASnI(3) precursor solution. We obtained the best films under the function of toluene or chlorobenzene in anti-solvent dripping method and monitored the oxidation of FASnI(3) films in air. We chose SnF(2) as an additive of CsSnI(3) precursor solution to prevent the oxidation of the Sn(2+), improving the stability of CsSnI(3). The experimental results we obtained can pave the way for lead-free tin-based perovskite solar cells (PSCs).