Liu Huanling, Wang Yan, Zhao Xin, Song Yuzhi, Lin Lili, Fan Jianzhong, Wang Chuan-Kui
Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China; State Key Laboratory of Luminescent Materials and Devices, South China University of Technology.
Spectrochim Acta A Mol Biomol Spectrosc. 2025 Jan 15;325:125110. doi: 10.1016/j.saa.2024.125110. Epub 2024 Sep 7.
Red and deep red (DR) organic light-emitting diodes (OLEDs) have garnered increasing attention due to their widespread applications in display technology and lighting devices. However, most red OLEDs exhibit low luminescence efficiency, severely limiting their practical applications. To address this challenge, we theoretically design four novel TADF molecules with red and DR luminescence using intramolecular locking strategies building upon the experimental findings of DCN-DLB and DCN-DSP, and their crystal structures are predicted with the lower energy and higher packing density. The photophysical properties and luminescence mechanism of six molecules in toluene and crystal are clarified using the first principles calculation and thermal vibration correlation function (TVCF) method. The proposed design strategy is anticipated to offer several advantages: enhanced electron-donating capabilities, more rigid structures, longer emission wavelengths and higher luminescence efficiency. Specifically, we introduce oxygen atoms and nitrogen atoms as intramolecular locks, and the newly developed DCN-DBF and DCN-PHC have redshifted emission, narrow singlet-triplet energy gap (ΔE), fast reverse intersystem crossing rate and enhanced photoluminescence quantum yield (PLQY). Notably, DCN-DBF achieves both long wavelength emission and high efficiency, with emission peaks at 598 nm and 587 nm corresponding to PLQY of 52.13 % and 43.42 % in toluene and crystal, respectively. Our work not only elucidates the relationship between molecular structures and photophysical properties, but also proposes feasible intramolecular locking design strategies and four promising red and DR TADF molecules, which could provide a valuable reference for the design of more efficient red and DR TADF emitters.
红色和深红色（DR）有机发光二极管（OLED）因其在显示技术和照明设备中的广泛应用而受到越来越多的关注。然而，大多数红色OLED的发光效率较低，严重限制了它们的实际应用。为应对这一挑战，我们基于DCN-DLB和DCN-DSP的实验结果，利用分子内锁定策略从理论上设计了四种具有红色和DR发光的新型热激活延迟荧光（TADF）分子，并预测了它们具有较低能量和较高堆积密度的晶体结构。使用第一性原理计算和热振动相关函数（TVCF）方法阐明了六种分子在甲苯和晶体中的光物理性质及发光机制。所提出的设计策略预计具有几个优点：增强的供电子能力、更刚性的结构、更长的发射波长和更高的发光效率。具体而言，我们引入氧原子和氮原子作为分子内锁定基团，新开发的DCN-DBF和DCN-PHC具有红移发射、窄的单重态-三重态能隙（ΔE）、快速的反向系间窜越速率和增强的光致发光量子产率（PLQY）。值得注意的是，DCN-DBF实现了长波长发射和高效率，在甲苯和晶体中的发射峰分别位于598 nm和587 nm，对应的PLQY分别为52.13%和43.42%。我们的工作不仅阐明了分子结构与光物理性质之间的关系，还提出了可行的分子内锁定设计策略以及四种有前景的红色和DR TADF分子，可为设计更高效的红色和DR TADF发光体提供有价值的参考。
