The pursuit of ideal short-delayed thermally activated delayed fluorescence (TADF) emitters is hampered by the mutual exclusion of a small singlet-triplet energy gap (ΔE_ST) and a large oscillator strength (f). Here, by attaching an multiresonance-acceptor onto a sterically-uncrowded donor, we report TADF emitters bearing hybrid electronic excitations with a main donor-to-acceptor long-range (LR) and an auxiliary bridge-phenyl short-range (SR) charge-transfer characters, balancing a small ΔE_ST and a large f. Moreover, the incorporation of dual equivalent multiresonance-acceptors is found to double the f value without affecting the ΔE_ST. A large radiative decay rate over an order of magnitude higher than the intersystem crossing (ISC) rate, and a decent reverse ISC rate of >10⁶ s⁻¹ are simultaneously obtained in one emitter, leading to a short delayed-lifetime of ~0.88 μs. The corresponding organic light-emitting diode exhibits a record-high maximum external quantum efficiency of 40.4% with alleviated efficiency roll-off and extended lifetime.

追求理想的短延迟热激活延迟荧光 (TADF) 发射器受到小单重态-三重态能隙 (Δ E _ST ) 和大振荡器强度 ( f )相互排斥的阻碍。在这里，通过将多共振受体连接到空间不拥挤的供体上，我们报告了带有混合电子激发的 TADF 发射器，主要供体-受体长程 (LR) 和辅助桥苯基短程 (SR) 电荷-转移字符，平衡小的 Δ E _ST和大的f。此外，发现双等效多共振受体的结合使f值加倍而不影响 Δ E _ST. 在一个发射器中同时获得了比系统间穿越 (ISC) 率高一个数量级的大辐射衰减率，以及 >10 6 ^s  -1^的良好反向 ISC 率，导致约 0.88 的短延迟寿命微秒。相应的有机发光二极管表现出创纪录的 40.4% 的最大外量子效率，并减轻了效率衰减并延长了使用寿命。