Indirect Control of Donor/Acceptor Interactions for Highly Efficient Space-Confined Thermally Activated Delayed Fluorescence Emitters,Advanced Functional Materials

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Indirect Control of Donor/Acceptor Interactions for Highly Efficient Space-Confined Thermally Activated Delayed Fluorescence Emitters
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2022-11-24 , DOI: 10.1002/adfm.202209708
Zi‐Qi Feng _{1,

2} , Sheng‐Yi Yang _{1,

2} , Fan‐Cheng Kong _{1,

2} , Yang‐Kun Qu _{1,

2} , Xin‐Yue Meng _{1,

2} , You‐Jun Yu _{1,

2} , Dong‐Ying Zhou _{1,

2} , Zuo‐Quan Jiang _{1,

2} , Liang‐Sheng Liao _{1,

2,

3}

Affiliation

Conformational engineering is essential to further reinforce the luminescent properties of thermally activated delayed fluorescence (TADF) materials featuring through-space charge transfer (TSCT) characteristics. Herein, two TSCT-TADF emitters (8MeDM-B and 8FDM-B) with the methyl and fluorine moieties substituted at the C8 site of the rigid spiro-fluorene bridge is reported. Derivation of the C8 site is first proposed to control the molecular configuration with the ability to indirectly tune the intramolecular interaction between donor and acceptor groups. As a result, 8MeDM-B and 8FDM-B both present small singlet-triplet energy gaps, fast reverse intersystem crossing rates, and high photoluminescence quantum yields. Interestingly, the smaller fluorine atom not the bigger methyl group exhibits more evident electrostatic repulsive force onto the central donor and thus rectifies the central spiro structure. Consequently, the high external quantum efficiency values of 28.8% and 31.7% for 8MeDM-B and 8FDM-B-based electroluminescence devices are achieved, respectively. This study offers a measure for enhancing TSCT-TADF emitters without directly modifying the donor or acceptor.

中文翻译：

间接控制高效空间受限热激活延迟荧光发射器的供体/受体相互作用

构象工程对于进一步增强具有穿透空间电荷转移 (TSCT) 特性的热激活延迟荧光 (TADF) 材料的发光性能至关重要。在此，报告了两个 TSCT-TADF 发射体（8MeDM-B 和 8FDM-B），其甲基和氟部分在刚性螺-芴桥的 C8 位点被取代。C8 位点的推导首先被提出来控制分子构型，能够间接调节供体和受体基团之间的分子内相互作用。因此，8MeDM-B 和 8FDM-B 都具有小的单重态-三重态能隙、快速的反向系间交叉率和高光致发光量子产率。有趣的是，较小的氟原子而不是较大的甲基对中心供体表现出更明显的静电排斥力，从而矫正中心螺结构。因此，基于 8MeDM-B 和 8FDM-B 的电致发光器件分别实现了 28.8% 和 31.7% 的高外量子效率值。本研究提供了一种在不直接修改供体或受体的情况下增强 TSCT-TADF 发射器的措施。

更新日期：2022-11-24

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