An organic light-emitting diode comprising, i) an anode A; ii) a hole-conducting layer B formed from at least one hole-conducting material; iii) a light-emitting layer C; iv) an electron-conducting layer D; v) a cathode E; where the layers A, B, C, D and E are arranged in the aforementioned sequence and one or more further layers may be arranged between layers A and B, B and C, C and D and/or D and E, wherein the light-emitting layer C comprises at least one hole-conducting material CA and at least one phosphorescence emitter CB, wherein a hole-blocking layer formed from at least one hole blocker material and/or exciton blocker material is present between the light-emitting layer C and the electron-conducting layer D in direct contact to the light-emitting layer C, characterized in that the at least one phosphorescence emitter CB is a transition metal-carbene complex of the general formula I in which the symbols are each defined as follows: M 1 is a metal atom selected from the group consisting of transition metals of groups IB, IIB, IIIB, IVB, VB, VIB, VIIB, VIIIB, the lanthanides and IIIA of the Periodic Table of the Elements (CAS version) in any oxidation state possible for the particular metal; carben is a carbene ligand which may be uncharged or monoanionic and mono-, bi- or tridentate; the carbene ligand may also be a bis- or triscarbene ligand; L is a mono- or dianionic ligand, preferably a monoanionic ligand, which may be mono- or bidentate; K is an uncharged mono- or bidentate ligand; n is the number of carbene ligands, where n is at least 1, preferably 1 to 6, and the carbene ligands in the complex of the formula I may be the same or different when n>1; m is the number of ligands L, where m may be 0 or ≧1, preferably 0 to 5, and the ligands L may be the same or different when m>1; o is the number of ligands K, where o may be 0 or ≧1, preferably 0 to 5, and the ligands K may be the same or different when o>1; p is the charge of the complex: 0, 1, 2, 3 or 4; W - is a monoanionic counterion; where the sum of n+m+o and p depends on the oxidation state and coordination number of the metal atom used, the charge of the complex and on the denticity of the carbene, L and K ligands, and on the charge of the carbene and L ligands, with the condition that n is at least 1, and that the at least one hole-conducting material of the hole-conducting layer B and the at least one hole-conducting material CA of the light-emitting layer C are carbene complexes of formula I, where the carbene complexes of the hole-conducting materials in layers B and C differ from the carbene complex of of the phosphorescence emitter CB, wherein the carbene complexes of the hole-conducting materials in layers B and C are the same or different, and the band gap of the carbene complexes used as the hole-conducting material is greater than the band gap of the at least one phosphorescence emitter CB. i) an anode A; ii) a hole-conducting layer B formed from at least one hole-conducting material; iii) a light-emitting layer C; iv) an electron-conducting layer D; v) a cathode E; M 1 is a metal atom selected from the group consisting of transition metals of groups IB, IIB, IIIB, IVB, VB, VIB, VIIB, VIIIB, the lanthanides and IIIA of the Periodic Table of the Elements (CAS version) in any oxidation state possible for the particular metal; carben is a carbene ligand which may be uncharged or monoanionic and mono-, bi- or tridentate; the carbene ligand may also be a bis- or triscarbene ligand; L is a mono- or dianionic ligand, preferably a monoanionic ligand, which may be mono- or bidentate; K is an uncharged mono- or bidentate ligand; n is the number of carbene ligands, where n is at least 1, preferably 1 to 6, and the carbene ligands in the complex of the formula I may be the same or different when n>1; m is the number of ligands L, where m may be 0 or ≧1, preferably 0 to 5, and the ligands L may be the same or different when m>1; o is the number of ligands K, where o may be 0 or ≧1, preferably 0 to 5, and the ligands K may be the same or different when o>1; p is the charge of the complex: 0, 1, 2, 3 or 4; W - is a monoanionic counterion; where the sum of n+m+o and p depends on the oxidation state and coordination number of the metal atom used, the charge of the complex and on the denticity of the carbene, L and K ligands, and on the charge of the carbene and L ligands, with the condition that n is at least 1, and that the at least one hole-conducting material of the hole-conducting layer B and the at least one hole-conducting material CA of the light-emitting layer C are carbene complexes of formula I, where the carbene complexes of the hole-conducting materials in layers B and C differ from the carbene complex of of the phosphorescence emitter CB, wherein the carbene complexes of the hole-conducting materials in layers B and C are the same or different, and the band gap of the carbene complexes used as the hole-conducting material is greater than the band gap of the at least one phosphorescence emitter CB.