 This study has developed a new type of TADF emitter which combines two types of electronic transitions, a main donor to accept a LR character and an auxiliary bridge phenyl SR character, to balance a small singlet triplet energy gap and a high oscillator strength. This allows for a large radiative decay rate and a good reverse inter-system crossing rate, resulting in a short delayed lifetime of 0.88 microseconds. The emitter also shows a record high maximum external quantum efficiency of 40.4% with alleviated efficiency roll-off and extended lifetime. This article was offered by Guayun Meng, Heng Yi Dai, Qi Wang, and others.