Method for manufacturing a layer of multi-cation perovskite to form photo-active layer involving slot die coating or a blade coating of wet film, and sweeping of the wet film by flow of dry air or inert gas having specified speed, and application of heat treatment to substrate

A method for manufacturing a layer of perovskite with multi-cations, with a view to form a photo-active layer, the method comprising the steps of:

• a) suppling a substrate having a deposition face,
• b) depositing a precursor solution comprising at least one solvent and perovskite precursors so as to form a wet film on the deposition face, the depositing being carried out by slot die coating or via a blade coating, the precursors comprising at least CsX, FAY, PbZ2, with X, Y and Z═I, Br, and an FACl additive, the amounts being determined such that the molar ratio of cesium to lead is comprised between about 4% and 22%, preferably between 13% and 20%, that the molar ratio of FACl relative to lead is comprised between 0.1% and 5%, in particular between 0.1% and 2%, and that the perovskite layer has a empirical formula of the CsxFA(1−x+w)Pb(IyBr(1−y))3 type with x comprised between 0.04 and 0.22, y comprised between 0 and 1 and w comprised between 0.001 and 0.05, and
• c) sweeping an exposed surface of the wet film by a flow of dry air or inert gas having a speed greater than or equal to 120 m/s so as to crystallize the multi-cations perovskite layer, the method further comprising the application of a heat treatment to the substrate so that the deposition face has a temperature ranging from about 25° C. to 80° C. at least during step b).