Hua Lei, Wu Han, Yan Shouke, Zhu Weiguo, Ren Zhongjie, Wang Yafei
School of Materials Science & Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications, Changzhou University, Changzhou, 213164, China.
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.
Chemistry. 2025 Jul 2;31(37):e202501391. doi: 10.1002/chem.202501391. Epub 2025 Jun 4.
Achieving efficient orange-red emission in thermally activated delayed fluorescence (TADF) emitters remains challenging due to the hard to achieve great balance between a small singlet-triplet energy gap and high radiative decay rates. In this study, a modification site engineering strategy for secondary donors to optimize excited-state properties for orange-red emitters is proposed. Two isomeric emitters, ND28DBT and ND37DBT, were synthesized by introducing dibenzothiophene (DBT) units at different positions of a naphthalimide-dimethylacridine (NAI-DMAc) core. The theoretical analysis indicates that ND37DBT possesses a more favorable excited-state configuration, which facilitates an efficient reverse intersystem crossing (RISC) process and accelerates the radiative decay rate. As a result, ND37DBT showed a high photoluminescence quantum yield (PLQY) (70%), a fast RISC rate (6.25 × 10 s), and an excellent external quantum efficiency (EQE) (22.1%) with minimal roll-off in 100 cd m. This work demonstrates that precise control of secondary donor modification sites offers a powerful molecular design strategy for developing high-efficiency orange-red TADF materials.
由于难以在较小的单重态-三重态能隙与高辐射衰减率之间实现良好平衡，在热激活延迟荧光（TADF）发光体中实现高效橙红色发射仍然具有挑战性。在本研究中，提出了一种用于二级供体的修饰位点工程策略，以优化橙红色发光体的激发态性质。通过在萘二甲酰亚胺-二甲基吖啶（NAI-DMAc）核的不同位置引入二苯并噻吩（DBT）单元，合成了两种异构体发光体ND28DBT和ND37DBT。理论分析表明，ND37DBT具有更有利的激发态构型，这有利于高效的反向系间窜越（RISC）过程并加速辐射衰减率。结果，ND37DBT表现出高光致发光量子产率（PLQY）（70%）、快速的RISC速率（6.25×10⁵ s⁻¹）以及优异的外量子效率（EQE）（22.1%），在100 cd m⁻²时滚降最小。这项工作表明，精确控制二级供体修饰位点为开发高效橙红色TADF材料提供了一种强大的分子设计策略。
