Method of manufacturing a large-grain crystallized metal chalcogenide film, and a crystallized metal chalcogenide film prepared using the method

A method for manufacturing a film of polycrystalline metal chalcogenide(s) with large crystalline grains of sizes at least equal to half the thickness of said film, by means of a colloidal solution consisting of:

• primary amorphous nanoparticles of metal chalcogenides of formula M-C dispersed in a hydro-alcoholic solvent,
• wherein:
• M represents one or several first metals, either identical or different, selected from the group consisting of Cu, Zn, and Sn, and
• C represents one or several chalcogenide elements, either identical or different, selected from S and Se,
• wherein said primary amorphous nanoparticles have a size of less than 30 nm, wherein the alcohol is a non-toxic alcohol having a boiling temperature below the boiling temperature of water, and wherein the hydro-alcoholic solution does not contain organic ligands, said film being deposited on one or more layered material(s) forming a substrate, said metal chalcogenide being of formula M-C wherein:
• M represents Cu, Zn, and Sn, and
• C represents one or more chalcogenide elements, either identical or different, selected from S and Se, wherein the following successive steps are carried out:
• 1) a layer of amorphous nanoparticles of metal chalcogenide(s) is deposited on said substrate from said aqueous, or hydro-alcoholic colloidal solution, and
• 2) heat treatment of said layer of metal chalcogenide(s) is carried out at a temperature of at least 300° C. in order to obtain densification of said layer of metal chalcogenide(s) and crystallization of the nanoparticles, over a thickness from 0.2 to 5 μm.