Electroluminescence from triplet metal—ligand charge-transfer excited state of transition metal complexes

Triplet metal—ligand charge-transfer (MLCT) excited-state emissions of some osmium(II) complexes Os(CN)2(PPh3)2X(X = bipyridine derivatives or anthroline derivatives) are enhanced upon incorporation into the poly(N-vinyl carbazole) (PVK) matrix. By employing a cell of indium—tin oxide (ITO)-coated glass/Os complex:PVK/2-(4-biphenyl)-5-(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD)/AI configuration, a stable and uniform red electroluminescence is observed over 8 V d.c. bias.