A metal-carbene complex of the general formula wherein M is Ir or Pt, R 1 and R 2 are independently of each other a linear or branched alkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 3 to 20 carbon atoms, substituted or unsubstituted aryl radical, optionally bearing at least one functional group and having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having a total of 5 to 18 carbon atoms and/or heteroatoms, A 1, A 2, A 3 and A 4 are independently from each other CR 3 or N; each R 3 is independently of each other H, a linear or branched alkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 3 to 20 carbon atoms, substituted or unsubstituted aryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having a total of 5 to 18 carbon atoms and/or heteroatoms; or a group with donor or acceptor action; K and L are independently from each other a bidentate monoanionic ligand; for M is Ir, o is 1, 2 or 3, m is 0, 1, or 2, n is 0, 1, or 2 and m+n+o= 3 and for M is Pt, o is 1, or 2, m is 0, or 1, n is 0, or 1 and m+n+o=2. M is Ir or Pt, R 1 and R 2 are independently of each other a linear or branched alkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 3 to 20 carbon atoms, substituted or unsubstituted aryl radical, optionally bearing at least one functional group and having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having a total of 5 to 18 carbon atoms and/or heteroatoms, A 1, A 2, A 3 and A 4 are independently from each other CR 3 or N; each R 3 is independently of each other H, a linear or branched alkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 3 to 20 carbon atoms, substituted or unsubstituted aryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radical optionally interrupted by at least one heteroatom, optionally bearing at least one functional group and having a total of 5 to 18 carbon atoms and/or heteroatoms; or a group with donor or acceptor action; K and L are independently from each other a bidentate monoanionic ligand; for M is Ir, o is 1, 2 or 3, m is 0, 1, or 2, n is 0, 1, or 2 and m+n+o= 3 and for M is Pt, o is 1, or 2, m is 0, or 1, n is 0, or 1 and m+n+o=2.