Multiresonance thermally activated delayed fluorescence (MR-TADF) materials have attracted widespread attention due to ultrahigh definition display standards. However, many MR-TADF materials lack TADF properties in both the solution and solid states. Interestingly, the TADF characteristics appear once these MR-TADF compounds are doped in a suitable host film, but the precise mechanism involved in the host–guest interaction remains uncertain. Herein, we systematically investigated the role of host–guest interactions employing doped films (DABNA-1@mCBP and DABNA-1@DPEPO) with opposite phenomena. The results indicate that mCBP with a V-shape and enhanced rigidity could facilitate the formation of an energy spacing layer by employing short-range Coulomb energy through the MR luminescent core, which could offset the sensitivity of the stacking distance, enhancing the coupling between T₁ and T₂, and thus switch the reverse internal conversion and the higher T₂ reverse intersystem crossing process. This work is a further development of luminescence mechanisms and an update of the host–guest interaction criteria for the targeted design of doped films.

中文翻译：

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短程库仑相互作用是切换多共振热激活延迟荧光掺杂薄膜中高三重态激子利用的关键


多共振热激活延迟荧光 （MR-TADF） 材料因其超高清显示标准而受到广泛关注。然而，许多 MR-TADF 材料在固溶态和固态下都缺乏 TADF 特性。有趣的是，一旦这些 MR-TADF 化合物掺杂在合适的主膜中，TADF 特性就会出现，但主客体相互作用所涉及的确切机制仍不确定。在此，我们系统地研究了使用具有相反现象的掺杂薄膜 （DABNA-1@mCBP 和 DABNA-1@DPEPO） 的主客体相互作用的作用。结果表明，具有 V 形和增强刚度的 mCBP 可以通过通过 MR 发光芯利用短程库仑能量来促进能量间距层的形成，这可以抵消堆叠距离的敏感性，增强 T₁ 和 T₂ 之间的耦合，从而切换反向内部转换和更高的 T₂反向系统间交叉过程。这项工作是发光机制的进一步发展，也是掺杂薄膜靶向设计的主客体相互作用标准的更新。