The utilization of triplet excitons is greatly concerned in organic luminophores. For thermally activated delayed fluorescence (TADF) emitters, the reverse intersystem crossing (RISC) which activates the triplet excitons at low temperature remains challenging without thermal stimulation. Herein, a temperature-dependent promotion relay of the triplet excitons from TADF to self-sensitized triplet − triplet annihilation up-conversion (TTA-UC) was demonstrated in an asymmetrical TADF luminophore based on 9,9-dimethyl-9,10-dihydroacridine (DMAC) donor and diphenylfonyl (DPS) acceptor. Single-crystal structure analysis combined with theoretical calculations revealed that the alternate strong-and-weak contact of the molecules reduced the singlet–triplet splitting energy (ΔE_ST), amplified the singlet–triplet coupling (SOC) strength and exciton coupling (EC), leading to highly efficient RISC process over a wide range of temperatures. Moreover, benefiting from the extreme small ΔE_ST value and large SOC strength, highly efficient blue OLEDs were achieved with the highest CE_max, PE_max and EQE_max of 32.0 cd A^-1, 33.5 lm W⁻¹ and 14.7%, and low efficiency roll-off. This work provides a design guidance for high utilization of the triplet excitons through RISC to improve the luminescence efficiency and reduce the device efficiency roll-off.

三重态激子的利用在有机发光体中受到极大关注。对于热激活延迟荧光（TADF）发射器，在低温下激活三重态激子的反向系间窜越（RISC）在没有热刺激的情况下仍然具有挑战性。在此，在基于 9,9-二甲基-9,10-二氢吖啶的不对称 TADF 发光体中证明了三重态激子从 TADF 到自敏三重态-三重态湮没上转换 (TTA-UC) 的温度依赖性促进中继（DMAC）供体和二苯甲酰（DPS）受体。单晶结构分析结合理论计算表明，分子的交替强弱接触降低了单线态-三线态分裂能（Δ E _ST），放大了单线态-三线态耦合（SOC）强度和激子耦合（EC），从而在很宽的温度范围内实现高效的RISC工艺。此外，得益于极小的Δ E _ST值和大的 SOC 强度，实现了高效蓝色 OLED，其最高CE _max、PE _max和EQE _max分别为 32.0 cd A ^-1、 33.5 lm W ^-1和 14.7% 。低效率滚降。这项工作为通过RISC高效利用三重态激子来提高发光效率并减少器件效率滚降提供了设计指导。