Tailoring the Spectra of White Organic Light-Emitting Devices by Trap Effect of a Concentration-Insensitive Dopant

Highly efficient phosphorescent organic light-emitting devices (PhOLEDs) had been fabricated by using a novel iridium complex, bis[2-(3′,5′-di-tert-butylbiphenyl-4-yl)benzothiazolato-N,C2′]iridium(III) (acetylacetonate) [(tbpbt)2Ir(acac)], as the emitter. With a wide doping ratio ranging from 15 wt% to 25 wt%, the PhOLEDs maintained a comparable high performance, indicating concentration-insensitive property of the (tbpbt)2Ir(acac). On the basis of the unique characteristic of concentration insensitivity, the application of this phosphor was explored by fabricating white organic light-emitting devices (WOLEDs) with altered doping ratio, indicating that trap effect of (tbpbt)2Ir(acac) could effectively tailor WOLEDs spectra. Typically, a high-power efficiency, current efficiency, and external quantum efficiency of 30.0 lm/W, 38.8 cd/A, 18.1%, were achieved by 20 wt% doped WOLEDs.