NOVELTY - Copper(I) complexes (I) are new.    USE - (I) are useful as an emitter or absorber for converting UV-radiation or blue light into visible light, preferably into green, yellow or red light in an optoelectronic component, preferably organic light-emitting components, light-emitting electrochemical cells, organic light-emitting diode-based sensors, preferably non-hermetically and outwardly shielded gas- and vapor sensors, organic solar cells, organic field effect transistors, organic lasers, down-conversion elements, organic diodes, organic transistors, organic light-emitting diodes, and organic field-effect transistors (all claimed).    ADVANTAGE - (I) comprises copper, which is cheap and less toxic, and exhibits high emission quantum yield (preferably greater than 50%).    DETAILED DESCRIPTION - Copper(I) complexes of formula (I) are new.    X = Cl, Br, I, CN, OCN, SCN, alkynyl and/or N3;    T1 = bidentate ligand of formula (N1T2E) (II) (optionally substituted by at least one group Z1);    E = phosphanyl, arsanyl or antimonyl group of type (R)2E;    R = alkyl, aryl, alkoxy, phenoxy or amide;    N1 = imine, which is component of aromatic group, preferably pyridyl, pyrimidyl, pyridazinyl, triazinyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, 1,2,4-triazolyl, 1,2,4-oxadiazolyl, 1,2,4-thiadiazolyl, tetrazolyl, 1,2,3,4-oxatriazolyl and/or 1,2,3,4-thiatriazolyl;    T2 = at least one C, which is component of aromatic group, where C is located directly adjacent to imine N and P, As or Sb;    L = D1(R)3 or (R)2D2-B1-D2(R)2 (optionally substituted by at least one group Z1);    D1 = phosphanyl, arsanyl or antimonyl group of type (R)3D1;    D2 = phosphanyl, arsanyl or antimonyl group of type (R)2D2, which is bonded with other group D2 through a bridge B1;    B1 = alkylene and/or arylene or -O-, -NR- or -Si(R)2-; and    Z1 = group for increasing charge carrier transport and/or for increasing solubility of (I) in an organic solvent.    INDEPENDENT CLAIMS are also included for:    (1) preparing (I);    (2) use of (I) as an emitter or absorber in an optoelectronic component;    (3) the optoelectronic component comprising (I);    (4) producing the optoelectronic component, comprising using (I); and    (5) modifying emission- and/or absorption properties of the electronic component, comprising introducing (I) into a matrix material for conducting electrons and holes in the optoelectronic component.