Electroluminescence of an iridium complex phosphorescent material doped polymeric system

With a novel iridium complex (pbi)(2) Ir (acac) doped into carbazole copolymer, polymer doped electrophosphorescent organic light-emitting diodes with the structure of indium-tin oxide(ITO)/poly(N-vinylcarbazole) (PVK) (pbi), Ir(acac) (x)/2,9-dimethyl-4,7-diphenyl-1, 10-phenan throline (BCP) (20 nm)/8-Hydroxyquinoline aluminum(Alq(3)) 10 nm)/Mg: Ag were fabricated. The photoluminescent (PL) and electroluminescent (EL) characteristics of the polymer doped system were investigated at the low doping concentrations of 0.1% and 0.5%, respectively. The results demonstrate that the luminescent spectra with different intensities of PVK and (pbi)(2)Ir (acac) co-existed in the PL and EL spectra of blend system, which was ascribed to an incomplete energy transfer process and direct charge trapping in the electroluminescence process. The 0.1% (pbi)(2)Ir (acac) doped device achieved a white light emission with the commissions internationale de 1' eclairage (CIE) coordinates of (0.32, 0.38) when the bias voltage was 19 V; the 0.5% (pbi)(2)Ir (acac) doped device had a maximum luminance of 11827 cd.m(-2) and a maximum luminance efficiency of 4.13 cd.A(-1) corresponding to a bias of 20.6 V and 13.4 V, respectively.