Use of a positively charged or neutral mono- or multinuclear copper complex comprising a structure of formula 1 in an optoelectronic device with L: ligand according to sub-formula 1 with E: arsenic or phosphorus; with R: R is at each occurrence identical or different and is H, D, an additional phenyl ring or heteroaryl ring substituted in meta-position by R' and optionally in para-position by R", such as pyridine, a linear alkyl, alkoxy or thioalkyl group having 1 to 8 C-atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 8 C-atoms or an alkenyl or alkynyl group having 2 to 8 C-atoms, wherein the aforementioned groups in each case can be substituted by one or more moieties R" and wherein one or more CH 2 -groups of the aforementioned groups can be replaced by R 3 C=CR 3 -, -C≡C-, Si(R 3) 2, C=O, C=S, C=NR 3, -C(=O)O-, - C(=O)NR 3 -, NR 3, P(=O)(R 3), -O-, -S-, SO or SO 2 and wherein one or more H-atoms inside the aforementioned groups can be replaced by D, or an aromatic ring system having 6 to 30 aromatic ring atoms, which can be substituted by one or more moieties R"', or an aryloxy group having 6 to 30 aromatic ring atoms, which can be substituted by one or more moieties R'''; with R': R' is identical or different at each occurrence and is methyl, ethyl, n-propyl, i-propyl, t-butyl, n-butyl, i-butyl, s-butyl; with R": R" is identical or different at each occurrence and is H, D, a linear alkyl, alkoxy or thioalkyl group having 1 to 8 C-atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 8 C-atoms or an alkenyl or alkynyl group having 2 to 8 C-atoms, phenyl, pyridyl, aryl; with R'": is identical or different at each occurrence and is H, alkyl or aryl; with R 3: is identical or different at each occurrence and is H, alkyl or aryl; with n = 0 or 1; with A, B: is a neutral or monoanionic, coordinating donor atom selected from each other the group consistent of N, P, As, S, O, F, Cl, Br, I, pseudo halogenide, which is optionally part of a bridging or chelating polydentate ligand and wherein in presence of B the copper complex CuLAAB is coordinated in particular tetrahedrally or pseudo tetrahedrally and in absence of B the resulting copper complex CuLAA comprises in particular a distorted trigonal planar geometry. with L: ligand according to sub-formula 1 with E: arsenic or phosphorus; with R: R is at each occurrence identical or different and is H, D, an additional phenyl ring or heteroaryl ring substituted in meta-position by R' and optionally in para-position by R", such as pyridine, a linear alkyl, alkoxy or thioalkyl group having 1 to 8 C-atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 8 C-atoms or an alkenyl or alkynyl group having 2 to 8 C-atoms, wherein the aforementioned groups in each case can be substituted by one or more moieties R" and wherein one or more CH 2 -groups of the aforementioned groups can be replaced by R 3 C=CR 3 -, -C≡C-, Si(R 3) 2, C=O, C=S, C=NR 3, -C(=O)O-, - C(=O)NR 3 -, NR 3, P(=O)(R 3), -O-, -S-, SO or SO 2 and wherein one or more H-atoms inside the aforementioned groups can be replaced by D, or an aromatic ring system having 6 to 30 aromatic ring atoms, which can be substituted by one or more moieties R"', or an aryloxy group having 6 to 30 aromatic ring atoms, which can be substituted by one or more moieties R'''; with R': R' is identical or different at each occurrence and is methyl, ethyl, n-propyl, i-propyl, t-butyl, n-butyl, i-butyl, s-butyl; with R": R" is identical or different at each occurrence and is H, D, a linear alkyl, alkoxy or thioalkyl group having 1 to 8 C-atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 8 C-atoms or an alkenyl or alkynyl group having 2 to 8 C-atoms, phenyl, pyridyl, aryl; with R'": is identical or different at each occurrence and is H, alkyl or aryl; with R 3: is identical or different at each occurrence and is H, alkyl or aryl; with n = 0 or 1; with A, B: is a neutral or monoanionic, coordinating donor atom selected from each other the group consistent of N, P, As, S, O, F, Cl, Br, I, pseudo halogenide, which is optionally part of a bridging or chelating polydentate ligand and wherein in presence of B the copper complex CuLAAB is coordinated in particular tetrahedrally or pseudo tetrahedrally and in absence of B the resulting copper complex CuLAA comprises in particular a distorted trigonal planar geometry.