Highly Efficient Nondoped OLEDs with Negligible Efficiency Roll-Off Fabricated from Aggregation-Induced Delayed Fluorescence Luminogens.

Purely organic emitters that can efficiently utilize triplet excitons are highly desired to cut the cost of organic light-emitting diodes (OLEDs), but most of them require complicated doping techniques for their fabrication and suffer from severe efficiency roll-off. Herein, we developed novel luminogens with weak emission and negligible delayed fluorescence in solution but strong emission with prominent delayed components upon aggregate formation, giving rise to aggregation-induced delayed fluorescence (AIDF). The concentration-caused emission quenching and exciton annihilation are well-suppressed, which leads to high emission efficiencies and efficient exciton utilization in neat films. Their nondoped OLEDs provide excellent electroluminescence efficiencies of 59.1 cd A-1 , 65.7 lm W-1 , and 18.4 %, and a negligible current efficiency roll-off of 1.2 % at 1000 cd m-2 . Exploring AIDF luminogens for the construction of nondoped OLEDs could be a promising strategy to advance device efficiency and stability.