Crystal structure and photoluminescence properties of CuBrxI1-x(melamine) (0 ≤ x ≤ 1) complexes

Organic-inorganic copper(I) halide complexes have attracted attention due to their optoelectronic properties and non-toxic nature. In this study, we systematically synthesized copper(I) halide melamine complexes as single crystals, (CuBr(melamine) and CuI(melamine)) and polycrystalline powders, CuBrxI1-x(melamine) (0 <= x <= 1). The crystal structures of CuBr(melamine) and CuI(melamine) are isotypic with a triclinic space group P 1<overline>$$ \overline{1} $$, where copper(I) is connected with three adjacent halides along the a-axis and a single melamine ligand along the c-axis, forming an infinite stair-chain structure. The photoluminescence emission peaks of CuBrxI1-x(melamine) (0 <= x <= 1) show a red shift from 455 nm to 520 nm with the substitution of Br for I. This finding explains the structure-property relationship of organic-inorganic copper(I) halide complexes and provides guidelines for developing new organic-inorganic optoelectronic materials.