Inorganic-organic hybrid IB-VII semiconductor compounds, in which a Group IB transition metal halide salt is coordinated with an organic heteroaromatic ligand, wherein at least one ring atom of said heteroaromatic ligand is a heteroatom independently selected from N, O and S and the Group IB metal of the halide salt is coordinated to a ring heteroatom. Also disclosed are semiconductor and light emitting devices comprising these materials, including light emitting diodes, and methods of preparing these materials and devices.