Electronic device comprising at least one light emitting layer between an anode (10, 20) and a cathode (13, 25), the device further comprising between the cathode (13, 25) and the anode (10, 20) at least one mixed layer characterized by comprising (i) in elemental form, an electropositive element selected from Li, Na, K, Be, Sc, Y, La, Lu, Ti and V, and (ii) at least one covalent electron transport matrix compound comprising at least one polar group selected from a) phosphine oxide group, wherein the reduction potential of the covalent electron transport matrix compound, if measured by cyclic voltammetry under the same conditions, has the value which is more negative than the value obtained for 4,7-diphenyl-1,10-phenanthroline, preferably more negative than for (9-phenyl-9H-carbazole-2,7-diyl)bis(diphenylphosphine oxide), more preferably more negative than for (9,9-dihexyl-9H-fluorene-2,7-diyl)bis(diphenylphosphine oxide), highly preferably more negative than for 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, even more preferably more negative than for 3-phenyl-3H-benzo[b]dinaphto[2,1-d:1',2'-f]phosphepine-3-oxide, most preferably more negative than for pyrene and still preferably more negative than for [1,1'-binaphthalen]-2,2'-diylbis(diphenylphosphine oxide) or b) diazole group, wherein the reduction potential of the covalent electron transport matrix compound, if measured by cyclic voltammetry under the same conditions, has the value which is more negative than the value obtained for 4,7-diphenyl-1,10-phenanthroline, preferably more negative than for (9-phenyl-9H-carbazole-2,7-diyl)bis(diphenylphosphine oxide), more preferably more negative than for (9,9-dihexyl-9H-fluorene-2,7-diyl)bis(diphenylphosphine oxide), highly preferably more negative than for 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, even more preferably more negative than for 3-phenyl-3H-benzo[b]dinaphto[2,1-d:1', 2'-flphosphepine-3-oxide, most preferably more negative than for pyrene and still preferably more negative than for [1,1'-binaphthalen]-2,2'-diylbis(diphenylphosphine oxide). (i) in elemental form, an electropositive element selected from Li, Na, K, Be, Sc, Y, La, Lu, Ti and V, and (ii) at least one covalent electron transport matrix compound comprising at least one polar group selected from a) phosphine oxide group, wherein the reduction potential of the covalent electron transport matrix compound, if measured by cyclic voltammetry under the same conditions, has the value which is more negative than the value obtained for 4,7-diphenyl-1,10-phenanthroline, preferably more negative than for (9-phenyl-9H-carbazole-2,7-diyl)bis(diphenylphosphine oxide), more preferably more negative than for (9,9-dihexyl-9H-fluorene-2,7-diyl)bis(diphenylphosphine oxide), highly preferably more negative than for 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, even more preferably more negative than for 3-phenyl-3H-benzo[b]dinaphto[2,1-d:1',2'-f]phosphepine-3-oxide, most preferably more negative than for pyrene and still preferably more negative than for [1,1'-binaphthalen]-2,2'-diylbis(diphenylphosphine oxide) or b) diazole group, wherein the reduction potential of the covalent electron transport matrix compound, if measured by cyclic voltammetry under the same conditions, has the value which is more negative than the value obtained for 4,7-diphenyl-1,10-phenanthroline, preferably more negative than for (9-phenyl-9H-carbazole-2,7-diyl)bis(diphenylphosphine oxide), more preferably more negative than for (9,9-dihexyl-9H-fluorene-2,7-diyl)bis(diphenylphosphine oxide), highly preferably more negative than for 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, even more preferably more negative than for 3-phenyl-3H-benzo[b]dinaphto[2,1-d:1', 2'-flphosphepine-3-oxide, most preferably more negative than for pyrene and still preferably more negative than for [1,1'-binaphthalen]-2,2'-diylbis(diphenylphosphine oxide). a) phosphine oxide group, wherein the reduction potential of the covalent electron transport matrix compound, if measured by cyclic voltammetry under the same conditions, has the value which is more negative than the value obtained for 4,7-diphenyl-1,10-phenanthroline, preferably more negative than for (9-phenyl-9H-carbazole-2,7-diyl)bis(diphenylphosphine oxide), more preferably more negative than for (9,9-dihexyl-9H-fluorene-2,7-diyl)bis(diphenylphosphine oxide), highly preferably more negative than for 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, even more preferably more negative than for 3-phenyl-3H-benzo[b]dinaphto[2,1-d:1',2'-f]phosphepine-3-oxide, most preferably more negative than for pyrene and still preferably more negative than for [1,1'-binaphthalen]-2,2'-diylbis(diphenylphosphine oxide) or b) diazole group, wherein the reduction potential of the covalent electron transport matrix compound, if measured by cyclic voltammetry under the same conditions, has the value which is more negative than the value obtained for 4,7-diphenyl-1,10-phenanthroline, preferably more negative than for (9-phenyl-9H-carbazole-2,7-diyl)bis(diphenylphosphine oxide), more preferably more negative than for (9,9-dihexyl-9H-fluorene-2,7-diyl)bis(diphenylphosphine oxide), highly preferably more negative than for 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, even more preferably more negative than for 3-phenyl-3H-benzo[b]dinaphto[2,1-d:1', 2'-flphosphepine-3-oxide, most preferably more negative than for pyrene and still preferably more negative than for [1,1'-binaphthalen]-2,2'-diylbis(diphenylphosphine oxide).