The state-of-the-art luminescent materials are gained widely by utilizing thermally activated delayed fluorescence (TADF) mechanism. However, the feasible molecular designing strategy of fully exploiting triplet excitons to enhance TADF properties is still in demand. Herein, TADF emitters with multiple conversion channels of triplet excitons are designed by concisely halogenating the electron acceptors containing carbonyl moiety. Compared with the chlorinated and brominated analogues, the fluorinated emitter exhibits distinguishing molecular stacking structures, participating in the formation of trimers through integrating CH···F and C═O···H hydrogen bonds together. It is also demonstrated that the multiple channels can be involved synergistically to accelerate the spin-flip of triplet excitons, and to take charge of the relatively superior reverse intersystem crossing constant rate of 6.20 × 10⁵ s^–1, and thus excellent photoluminescence quantum yields over 90% can easily be achieved. Then the solution-processable organic light emitting diode based on fluorinated emitter can achieve a record-high external quantum efficiency value of 27.13% and relatively low efficiency roll-off with remaining 24.74% at 1000 cd m⁻². This result manifests the significance of enhancing photophysical properties through constructing multiple conversion channels of triplets excitons for high-efficiency TADF emitters and provides a guideline for the future study.

中文翻译：

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采用具有多个三重态激子转换通道的热激活延迟荧光发射器，可实现高效溶液加工 OLED

利用热激活延迟荧光（TADF）机制广泛获得了最先进的发光材料。然而，仍然需要充分利用三重态激子来增强 TADF 性能的可行分子设计策略。在此，通过对含有羰基部分的电子受体进行简明卤化，设计了具有多个三线态激子转换通道的TADF发射器。与氯化和溴化类似物相比，氟化发光体表现出独特的分子堆叠结构，通过将CH·F和C=O·H氢键整合在一起参与三聚体的形成。实验还证明，多个通道可以协同参与，加速三重态激子的自旋翻转，并承担相对优越的反向系间窜越恒定速率6.20 × 10 5 ^s –1 ^，从而获得优异的光致发光量子产率90%以上可以轻松实现。然后，基于氟化发射体的可溶液加工有机发光二极管可以实现创纪录的27.13%的外量子效率值和相对较低的效率滚降，在1000 cd m ^-2下剩余24.74% 。该结果体现了通过构建高效TADF发射器的多个三重态激子转换通道来增强光物理性质的重要性，并为未来的研究提供了指导。