LAUSR

Nowadays, purely organic materials with delayed fluorescence (DF) are being enthusiastically developed and extensively utilized as light-emitting materials to fabricate OLEDs because of their high exciton utilization and metal-free nature. These DF materials usually have a small single-triplet splitting (ΔEST), and the nonradiative triplet excitons (75%) can be converted into radiative singlet excitons via thermally promoted reverse intersystem crossing (RISC) processes, endowing their OLEDs with potential internal quantum efficiencies (IQEs) approaching 100%. Although many OLEDs based on conventional DF emitters have high efficiencies and highmaximumbrightness, they usually have to face two practical obstacles which frustrate their commercial applications: namely, complicated device architectures with a host-guest doping system as the emitting layer, and serious efficiency roll-off at high luminance. Aggregation-induced emission luminogens (AIEgens) have been demonstrated to be excellent solid-state emitters, which makes them ideal materials for the fabrication of nondoped OLEDs. Moreover, AIEgens generally possess weak intermolecular interactions in the aggregated state, which is conducive to alleviating aggregation-caused exciton annihilation and efficiency roll-off. To date, many nondoped OLEDs with high performances have been constructed based