Although OLEDs employing DiKTa-based TADF emitters have achieved excellent EQEmax, aggregation remains an issue at higher doping concentrations within the emissive layer, resulting in aggregation-caused quenching (ACQ) and undesired exciton annihilation processes. Low emitter doping concentrations are usually required within the emitting layers to alleviate this problem. However, a very low doping of the emitter in the host leads to a narrower exciton recombination zone within the emitting layer (EML). The high concentration of excitons formed in host materials at high voltage are more likely to undergo bimolecular quenching processes such as triplet-triplet or triplet-polaron annihilation, which results in severe efficiency roll-off at high current density and poor device stability. In addition, there have been only a few reports of MR-TADF LECs (Figure , Table ) and their efficiencies are much worse than those of D-A TADF LECs. Thus, there remains outstanding