Vapor phase deposition of lead-free halide perovskite alloy CsSn_1-x Zn _x Br₃

Abstract We have investigated vapor phase deposition of lead-free all-inorganic perovskite CsSn 1- x Zn x Br 3 thin films (x = 0, 0.01, 0.02, 0.04, 0.10, 0.20 and 1.00) by co-evaporation of CsBr, SnBr 2 , and ZnBr 2 . We found that zinc ions can be incorporated into the perovskite lattice by substitution of up to 4% tin ions. Incorporation of zinc ions narrowed the band gap and suppressed oxidation of Sn 2+ .The deposited CsSn 1- x Zn x Br 3 polycrystalline thin films were of better quality compared to pure CsSnBr 3 , showing improved morphologies with fewer pinholes and larger grains. These properties of CsSn 1- x Zn x Br 3 will lead to the realization of efficient and stable lead-free perovskite solar cells.