New iridium complex as high-efficiency red phosphorescent emitter in polymer light-emitting devices

A new heteroleptic iridium complex Ir(1-piq)(2)pt with 1-phenylisoquinoline and 3-(pyridin-29-yl)1H- 1,2,4-triazole was synthesized and characterized. The complex was incorporated into phosphorescent polymer light-emitting devices using polyhedral oligomeric silsesquioxane-terminated polyfluorene (PFO-poss) as a host polymer doped with 30% of electron transport materials 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD). Red electrophosphorescence was observed with a peak emission at 605 nm. The highest-efficiency polymer light-emitting diode was achieved with PFO-poss doped with 2% Ir(1-piq) 2pt. An external quantum efficiency of 10.4% and a luminous efficiency of 9.4 cd A(-1) were obtained at 10.8 mA cm(-2). These values were found to be 7.67% and 5.99 cd A(-1) at 100 mA cm(-2).