Organic electroluminescent device comprising cathode, anode and an emitting layer, which comprises the following compounds: a) an electron-transporting compound, and b) a luminescent organic compound which has a separation between the lowest triplet state T 1 and the first excited singlet state S 1 of ≤ 0.15 eV; the LUMO, the T 1 state and the S 1 state are determined here via quantum-chemical calculations using the "Gaussian09W" software package (Gaussian Inc.) as follows: - in order to calculate organic substances without metals, a geometry optimisation is carried out using the "Ground State/Semi-empirical/ Default Spin/AM1/Charge 0/Spin Singlet" method; - an energy calculation is then carried out on the basis of the optimised geometry using the "TD-SFC/DFT/Default Spin/B3PW91" method with the "6-31 G(d)" base set (Charge 0, Spin Singlet); - for the calculation of metal-containing compounds, the geometry is optimised via the "Ground State/Hartree-Fock/Default Spin/ LanL2MB/Charge 0/Spin Singlet" method and the energy calculation is carried out analogously to the organic substances, with the difference that the "LanL2DZ" base set is used for the metal atom and the "6-31G(d)" base set is used for the ligands; - the LUMO energy level in electron volts calibrated with reference to cyclic voltammetry measurements is determined from the LUMO energy level LEh in hartree units obtained from the energy calculation as follows: LUMO eV = LEh * 27.212 − 2.0041 / 1.385; - T 1 is the energy of the triplet state having the lowest energy which arises from the quantum-chemical calculation described; - S 1 is the energy of the excited singlet state having the lowest energy which arises from the quantum-chemical calculation described; characterised in that the electron-transporting compound has an LUMO ≤ -2.5 eV. a) an electron-transporting compound, and b) a luminescent organic compound which has a separation between the lowest triplet state T 1 and the first excited singlet state S 1 of ≤ 0.15 eV; - in order to calculate organic substances without metals, a geometry optimisation is carried out using the "Ground State/Semi-empirical/ Default Spin/AM1/Charge 0/Spin Singlet" method; - an energy calculation is then carried out on the basis of the optimised geometry using the "TD-SFC/DFT/Default Spin/B3PW91" method with the "6-31 G(d)" base set (Charge 0, Spin Singlet); - for the calculation of metal-containing compounds, the geometry is optimised via the "Ground State/Hartree-Fock/Default Spin/ LanL2MB/Charge 0/Spin Singlet" method and the energy calculation is carried out analogously to the organic substances, with the difference that the "LanL2DZ" base set is used for the metal atom and the "6-31G(d)" base set is used for the ligands; - the LUMO energy level in electron volts calibrated with reference to cyclic voltammetry measurements is determined from the LUMO energy level LEh in hartree units obtained from the energy calculation as follows: LUMO eV = LEh * 27.212 − 2.0041 / 1.385; - T 1 is the energy of the triplet state having the lowest energy which arises from the quantum-chemical calculation described; - S 1 is the energy of the excited singlet state having the lowest energy which arises from the quantum-chemical calculation described;