The invention relates to copper(I) complexes of the formula A, formula (A), in which X* = Cl, Br, I, CN and/or SCN (independently of one another); Ν*∩Ε = a bidentate ligand, where E = phosphanyl/arsenyl group of the form R
2 E (where R = alkyl, aryl, alkoxyl, phenoxyl, or amid); N* = imine function which is a component of an N heteroaromatic 5- or 6-ring selected from the group consisting of oxazole, imidazole, thiazole, isoxazole, isothiazole, pyrazole, 1,2,3-triazole, 1,2,3-oxadiazole, 1,2,5-oxadiazole, 1,2,3-thiadiazole, 1,2,5-thiadiazol, pyridine, pyrimidine, triazine, pyrazine, and pyridazine; and ,,∩" = at least one carbon atom that is likewise a component of the aromatic group, said carbon atom being directly adjacent to both the imine nitrogen atom as well as to the phosphorous or arsenic atom.