Abstract: A method for manufacturing a multi-cation perovskite layer, including: a) supply of a substrate having a deposition face, b) deposition of a precursor solution including precursors comprising CsX, FAY, PbZ2, with X, Y and Z = I, Br, and an FAC1 additive, the molar ratio of cesium to lead is between approximately 4 % and 22%, the molar ratio of FAC1 relative to lead between 0.1% and 5%, and the perovskite layer has an empirical formula of the type CsxFA(1-x+w)Pb(IyBr(1-y))3 with x between 0.04 and 0.22, y between 0 and 1 and w between 0.001 and 0.05, c) sweeping of the wet film by an inert gas to crystallize the perovskite layer, and heat treatment so that the deposition face has a temperature ranging from about 25° C. to 80° C. C at least during step b).