High-efficiency polymer electrophosphorescent diodes based on an Ir (III) complex

Single-layer high-efficiency green electrophosphorescent light-emitting diodes were fabricated by doping an iridium complex bearing pinene group-tris(5-phenyl-10,10-dimethyl-4-aza- tricycloundeca-2,4,6-triene) Iridium(III)-into a blended host of poly(vinylcarbazole) and 2-(4-biphenylyl)-5-(4-tert-butulphenyl)-1,3,4-oxadiazol. The optimized device shows a turn-on voltage below 4 V, and a very high peak luminescent efficiency of 29.0 cdA. Comparing with the state-of-the-art electrophosphorescent devices, the present device has a much slower decrease of efficiency with increase of current density; a high efficiency of 20.7 cdA can still be achieved at a high current density of 150 mA cm2 (brightness=30 800 cd m2). © 2005 American Institute of Physics.