Highly efficient and color stable single-emitting-layer fluorescent WOLEDs with delayed fluorescent host

Abstract We demonstrated highly efficient and color stable single-emitting-layer fluorescent WOLEDs using blue thermally activated delayed fluorescent material of bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) as host and traditional orange fluorescent material of (5,6,11,12)-tetraphenyl-naphthacene (rubrene) as dopant. At a low dopant concentration of 0.6 wt%, we achieved the efficient white emission that comprised of blue host and orange dopant. The maximum current efficiency, power efficiency and external quantum efficiency were 20.2 cd A −1 , 15.9 lm W −1 and 7.48%, respectively. Besides, the Commission Internationale de I’Eclairage coordinates were almost the same with the increased voltage, which shifted from (0.359, 0.439) to (0.358, 0.430) as the voltage rose from 5 V to 8 V. The achievement of so high efficiency was attributed to the efficient up-conversion of DMAC-DPS triplet excitons and efficient energy transfer from host to dopant by Forster transfer mechanism. The more detailed working mechanism was also argued.