Novel iridium complex and its copolymer with N-vinyl carbazole for electroluminescent devices

A novel iridium complex having the polymerizable functional group as one of the ligands, bis(2-phenylene pyridine) acrylate iridium lr(ppy)2Ac was synthesized as a phosphorescent dopant for electroluminescent (EL) devices. It has a photoluminescence spectrum peak at about 530 nm. EL devices were fabricated by doping lr(ppy)2Ac into host materials, such as BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and poly(N-vinyl carbazole) (PVCz). Bright blue-green luminescence of about 12 000 cd/m2 was observed for an EL device having a structure of indium-tin oxide JTO)/1r(ppy)2Ac-doped TPD:PVCz/BCP/Alq3 [tris(8-hdroxyquinoline) aluniinuml/Mg:Ag. Furthermore, the iridium complex was copolymerized with N-vinyl carbazole (VCz) to form a random copolymer with a number average molecular weight of about 1000. An EL device using this hole-transport layer gave bright blue-green emission of more than 6000 cd/m2. These results indicate that lr(ppy)2Ae, especially its copolymer with VCz, can be a promising phosphorescent material for organic EL devices.