One-step solution synthesis and stability study of inorganic perovskite semiconductor Cs2SnI6

Inorganic perovskite semiconductor Cs 2 SnI 6 is a promising solar light absorber material to replace its unstable organic-inorganic counterpart in perovskite solar cells. However, at present its synthesis method is still complex and expensive. Here we report a simple one-step solution method to synthesize the Cs 2 SnI 6 powder, and then the effects of reactant type, reactant ratio and reaction solvent on the purity, crystallinity, optical and electrical properties, air and thermal stability of the Cs 2 SnI 6 power were studied. We find that pure and crystalline Cs 2 SnI 6 powder can be achieved in acetonitrile or anhydrous ethanol with a CsI:SnI 2 ratio of 1:1, or with a CsI:SnI 4 ratio of 3:2 (or 2:1). Cs 2 SnI 6 film with better crystallinity usually has a stronger optical absorption, a lower carrier concentration, a higher carrier mobility, and a better air and thermal stablity. Optical absorption of Cs 2 SnI 6 synthesized in anhydrous ethanol and acetonitrile keeps almost unchanged at the anneal temperature up to 150 °C.