Green-Yellow Electrophosphorescence from di 2,5-diphenyl-1,3,4-oxadiazole C², N³ Platinum(II) Doped PVK Devices

Employing a blend of poly (N-vinylcarbazole) (PVK) and 5-biphenyl-2-(4-tert-butyl)phenyl-1,3,4-oxadiazole) (PBD) as host matrix and a novel bicyclometalated Pt-complex containing 1,3,4-oxadiazole moiety as guest matrix with 2wt.% doping concentration, we have demonstrated efficient phosphorescence-based polymer light-emitting devices (PLEDs). The devices emitted intense green--yellow electrophosphorescence. No emission from either PVK or PBD was observed for the devices. The electroluminescence spectrum exhibited three primary peaks at 525nm, 568nm and 608nm. A maximum external quantum efficiency of 2.3% ph/el and a luminous efficiency of 3.8cd/A were achieved at a current density of 3.4mA/cm². The results demonstrate that highly efficient electrophosphorescence can be achieved from platinum complex-based polymer light-emitting devices.