Rational Design of Ir(III) Phosphors to Strategically Manage Charge Recombination for High-Performance White Organic Light-Emitting Diodes.

Constructing high-quality white organic light-emitting diodes (WOLEDs) remains a big challenge because of high demands on the electroluminescence (EL) performance including high efficiency, excellent spectral stability, and low roll-off simultaneously. To achieve effective energy transfer and trap-assisted recombination in the emissive layer, herein, four Ir(III) phosphors, namely, (), (), (), and (), were strategically designed via simple regulation of the substituent moiety and π conjugation of the chelated ligands. Their photophysical and EL properties were systematically investigated. When these phosphors are employed as doped emitters, the monochromic green organic light-emitting diodes not only exhibit a superior performance with the characteristics of 50.2 cd A, 39.2 lm W, and 15.1%, but also maintain a negligible roll-off ratio of 0.2% at 1000 cd m, which are better than those of commercial green Ir(ppy)acac and Ir(ppy) in the same device configuration. Inspired by these outstanding performances, we successfully fabricated the warm WOLED utilizing as a green component, affording a peak efficiency of 42.0 cd A, 29.3 lm W, and 18.6% and retaining at 39.9 cd A, 23.7 lm W, and 17.4% even at 1000 cd m. The results herein demonstrate the superiority of the molecular design and propose a simple method toward the development of promising Ir(III) phosphors for high-efficiency WOLEDs.