High-efficiency solution-processed WOLEDs with very high color rendering index based on a macrospirocyclic oligomer matrix host

Phosphorescent white organic light-emitting diodes (WOLEDs) with high efficiency and color rendering index (CRI) are demonstrated based on a macrospirocyclic oligomer matrix (TPA-PO)₃, which exhibits good solution processability, stable film morphology, and excellent compatibility with phosphorescent emitters. High-efficiency blue, green, orange, and red OLEDs were demonstrated with maximum current efficiencies of 21.7, 21.9, 13.1, and 6.4 cd A^-1, maximum brightness of 22475, 67757, 21232, and 8046 cd m^-2, respectively. Furthermore, by simultaneously incorporating blue, green, orange, and red emitters into a single emitting layer, a quaternary doping WOLED with a maximum current efficiency of 18.9 cd A^-1 (at 280 cd m^-2) was realized, featuring a "warm-white" light emission with correlated color temperatures ranging from 2841 to 3514 K. Importantly, color rendering index values over 90 were obtained at practical brightness of 100 ~1000 cd m^-2. Even at a high brightness of ~5000 cd m^-2, the CRI was still above 88, which is among the highest CRI values achieved for solution-processed phosphorescent WOLEDs.