Copper complex for the emission of light with a structure according to formula A wherein: Cu: Cu; X: Cl, Br, I, SCN, CN, and/or alkynyl (R*-≡) (R* is defined like R); P∩N: a phosphine ligand substituted with an N-hetereocycle with a structure according to formula B wherein: E: a carbon or nitrogen atom; E': a carbon or nitrogen atom, which is not substituted with a hydrogen atom; dotted bond: a single or double bond; R: alkyl group [CH 3 -(CH 2) n -] (n = 0 - 20), optionally branched or substituted with halogens (F, Cl, Br, I), or aryl group (especially phenyl), optionally substituted with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR* 3) (R* defined like R1 below) or ether groups -OR** (R** defined like R1 below), or unsaturated group such as alkenyl and alkynyl groups, optionally substituted again with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR*** 3) or ether groups -OR*** (R*** defined like R1 below), wherein R is no hydrogen atom; R', R": alkyl groups [CH 3 -(CH 2) n -] (n = 0 - 20, preferably n > 6), which can also be branched or cyclic, or aryl and heteroaryl groups, which is optionally substituted with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR* 3) or ether groups -OR* (R* defined like R1), wherein R' und R" each are directly bound to the phosphorous atom of the phosphine ligand; and wherein the N-heterocycle is an aromatic 6- or 5-membered ring, which is chosen from: wherein R1, R2, R3: defined like R, wherein R1, R2, R3 optionally is a hydrogen atom; and wherein R, R1, R2, R3 optionally form annulated ring systems; and wherein the N-heterocycle is linked to the phosphorous atom at the positions marked with "#". Cu: Cu; X: Cl, Br, I, SCN, CN, and/or alkynyl (R*-≡) (R* is defined like R); P∩N: a phosphine ligand substituted with an N-hetereocycle with a structure according to formula B wherein: E: a carbon or nitrogen atom; E': a carbon or nitrogen atom, which is not substituted with a hydrogen atom; dotted bond: a single or double bond; R: alkyl group [CH 3 -(CH 2) n -] (n = 0 - 20), optionally branched or substituted with halogens (F, Cl, Br, I), or aryl group (especially phenyl), optionally substituted with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR* 3) (R* defined like R1 below) or ether groups -OR** (R** defined like R1 below), or unsaturated group such as alkenyl and alkynyl groups, optionally substituted again with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR*** 3) or ether groups -OR*** (R*** defined like R1 below), wherein R is no hydrogen atom; R', R": alkyl groups [CH 3 -(CH 2) n -] (n = 0 - 20, preferably n > 6), which can also be branched or cyclic, or aryl and heteroaryl groups, which is optionally substituted with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR* 3) or ether groups -OR* (R* defined like R1), wherein R' und R" each are directly bound to the phosphorous atom of the phosphine ligand; E: a carbon or nitrogen atom; E': a carbon or nitrogen atom, which is not substituted with a hydrogen atom; R: alkyl group [CH 3 -(CH 2) n -] (n = 0 - 20), optionally branched or substituted with halogens (F, Cl, Br, I), or aryl group (especially phenyl), optionally substituted with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR* 3) (R* defined like R1 below) or ether groups -OR** (R** defined like R1 below), or unsaturated group such as alkenyl and alkynyl groups, optionally substituted again with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR*** 3) or ether groups -OR*** (R*** defined like R1 below), wherein R is no hydrogen atom; R', R": alkyl groups [CH 3 -(CH 2) n -] (n = 0 - 20, preferably n > 6), which can also be branched or cyclic, or aryl and heteroaryl groups, which is optionally substituted with alkyl groups, halogens (F, Cl, Br, I), silane (-SiR* 3) or ether groups -OR* (R* defined like R1), wherein R' und R" each are directly bound to the phosphorous atom of the phosphine ligand; R1, R2, R3: defined like R, wherein R1, R2, R3 optionally is a hydrogen atom; and wherein R, R1, R2, R3 optionally form annulated ring systems; and wherein the N-heterocycle is linked to the phosphorous atom at the positions marked with "#".