Abstract: The present invention relates to a process for producing a layer of a crystalline A/M/X material, which crystalline A/M/X material comprises a compound of formula [A]a[M]b[X]c, wherein: [M] comprises one or more first cations, which one or more first cations are metal or metalloid cations; [A] comprises one or more second cations; [X] comprises one or more halide anions; a is an integer from 1 to 6; b is an integer from 1 to 6; and c is an integer from 1 to 18, wherein the process comprises disposing on a substrate a precursor composition comprising: (a) a first precursor compound comprising a first cation (M), which first cation is a metal or metalloid cation; and (b) a solvent, and wherein the solvent comprises: (i) a non-polar organic solvent which is a hydrocarbon solvent, a chlorohydrocarbon solvent or an ether solvent; and (ii) a first organic amine comprising at least three carbon atoms. Also described are compositions useful in the process of the invention.

Abstract: The present invention relates to a process for producing a layer of a crystalline A/M/X material, which crystalline A/M/X material comprises a compound of formula [A]a[M]b[X]c, wherein: [M] comprises one or more first cations, which one or more first cations are metal or metalloid cations; [A] comprises one or more second cations; [X] comprises one or more halide anions; a is an integer from 1 to 6; b is an integer from 1 to 6; and c is an integer from 1 to 18, wherein the process comprises disposing on a substrate a precursor composition comprising: (a) a first precursor compound comprising a first cation (M), which first cation is a metal or metalloid cation; and (b) a solvent, and wherein the solvent comprises: (i) a non-polar organic solvent which is a hydrocarbon solvent, a chlorohydrocarbon solvent or an ether solvent; and (ii) a first organic amine comprising at least three carbon atoms. Also described are compositions useful in the process of the invention.