NOVELTY - Copper(I) complexes (A) are new.    USE - (A) is useful as emitter or absorber in an optoelectronic component, which is organic LED, light-emitting electrochemical cells, organic-LED sensors, preferably non-hermetically externally shielded gas and vapor sensors, organic solar cells, organic field-effect transistors, organic lasers, down-conversion elements, organic diode and organic transistors (all claimed).    ADVANTAGE - (I) are nontoxic. (I) provides optoelectronic devices with a wide range of achievable emission colors and high emission quantum yield, preferably greater than 50% without quenching effects.    DETAILED DESCRIPTION - Copper(I) complexes of formula (A) are new.    X = Cl, Br, I, CN and/or SCN;    NarcE = a bidentate ligand (B1), preferably oxazole group of formula (a) or (b), a nitrogen containing aryl group of formula (c)-(e), pyridine group of formula (f), pyrimidine of formula (g) or (h), (1,3,5)triazine group of formula (i), pyrazine group of formula (j) or pyridazine group of formula (k), where NarcE optionally comprises at least one substituent for increasing the solubility of (A) in an organic solvent, where the substituent is linear, branched or cyclic long-chain 1-30C-alkyl, linear, branched or cyclic long-chain 1-30C-alkoxy, linear or branched long-chain or cyclic 1-30C-perfluoroalkyl or short-chain polyethers with a chain length of 3-50 repeating units;    E = phosphanyl/arsenyl group of formula R2E;    R = alkyl, aryl, alkoxy, phenoxy or amide;    N1 = imine function which is a component of 5- or 6-membered N-heteroaryl ring 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-thiadiazole, pyridine, pyrimidine, triazine, pyrazine or pyridazine;    arc = at least one carbon atom that is likewise a component of the aryl group, where C atom being directly adjacent to both the imine nitrogen atom and to P or Ar atom;    Y1 = NR2, O or S; and    R1-R5 = H, halo, a substituent bonded over O, N or Si, linear, branched or cyclic alkyl, aryl, heteroaryl, alkenyl and/or alkynyl, branched or cyclic alkyl, aryl, heteroaryl and/or alkenyl groups with substituted by halo or D, branched or cyclic alkyl, donor or acceptor groups e.g. amines, carboxylates or their esters or CF3, where R2-R5 optionally forms a fused ring systems.    INDEPENDENT CLAIMS are included for:    (1) the preparation of (A);    (2) an optoelectronic component comprising (A);    (3) preparing the optoelectronic component using (A);    (4) the bidentate ligand (B1); and    (5) the preparation of 11 bidentate ligands (B1) e.g. comprising reacting 2-chloro-pyridine compound of formula (f1), 2-chloro-pyrimidine compound of formula (g1), 2-chloro-(1,3,5)triazine compound of formula (i1), 2-chloro-pyrazine compound of formula (j1) or 3-chloro-pyridazine compound of formula (k1) with a lithium compound of formula (E(R1)2Li) (T) to obtain pyridine group (f), pyrimidine group (g), triazine group (i), pyrazine group (j) or pyridazine group (k), respectively.