Abstract
Solution processing enables organic devices to be fabricated cost-effectively, while deep-red emitters enable displays with high color saturation and lighting with high light quality. However, limited deep-red emitters were reported with solution-process feasibility and high efficiency. We demonstrate here a high-efficiency, solution-process-feasible deep-red emitter by coupling the highly efficient phosphorescent complex with a highly thermally stable fluorescent compound. The device exhibits a maximum external quantum efficiency of 11.2% at 10 cd m -2 and 8.4% at 100 cd m -2 . The latter is coupled with an ultradeep red emission (0.70, 0.27) and a potential color saturation of 108%. Besides the intrinsically high-efficiency nature of the phosphorescent complex, the record high efficiency may be attributable to the spirally configured fluorene moiety in the fluorescent compound to prevent concentration-quenching effect, a proper host to enable an effective host-to-guest energy transfer, and the employed cohost with electron-trapping character to enable a balanced carrier injection.