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 Ir(PPY)(2)Ac 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 Ir(ppy)(2)Ac 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/m(2) was observed for an EL device having a structure of indium-tin oxide (ITO)/Ir(ppy)(2)Ac-doped TPD:PVCz/BCP/Alq(3) [tris(8-hdroxyquinoline) aluminum]/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/m(2). These results indicate that Ir(ppy)(2)Ac, especially its copolymer with VCz, can be a promising phosphorescent material for organic EL devices.