Enhancing Reverse Intersystem Crossing Rate of Red Thermally Activated Delayed Fluorescence Emitters by Simultaneously Involving Locally Excited Triplet States from Donor and Acceptor Segments
Enhancing Reverse Intersystem Crossing Rate of Red Thermally Activated Delayed Fluorescence Emitters by Simultaneously Involving Locally Excited Triplet States from Donor and Acceptor Segments
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DOI：
10.1016/j.cej.2023.141915
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发表时间：
2023-02
影响因子：
15.1
通讯作者：
Hui Wang;Xi Zhang;Lu Zhou;Xiaochun Fan;Ying-Chun Cheng;Jia Yu;Jiaxiong Chen;Kai Wang;
中科院分区：
文献类型：
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作者：
Hui Wang;Xi Zhang;Lu Zhou;Xiaochun Fan;Ying-Chun Cheng;Jia Yu;Jiaxiong Chen;Kai Wang;
加速红色热激活延迟荧光（TADF）发射体的反向系间穿越（RISC）速率至关重要，但仍然是持续的挑战。在此，我们公开了一种巧妙的分子设计，通过利用来自供体和受体片段（3LED和3LEA）的局部激发三重态的有效参与来显著地促进这样的上转换过程。令人鼓舞的是，在DBBPZ-IDPZ的情况下，通过同时使用多环大共轭供体和受体单元，获得了接近电荷转移单重态和三重态（1CT和3CT）的3LEA-3LED能级对准。由于3LED和3LEA的共同贡献，DBBPZ-IDPZ显示出15.7倍的加速RISC速率，并且相对于对照分子（36.7%）提供更高的光致发光量子产率98.1%。最终，基于DBBPZ-IDPZ的红色OLED呈现出26.0%的显著改善的外量子效率，在628 nm处具有发射最大值，这大约是对照器件（8.9%）的三倍。这是第一个精细管理3LED和3LEA同时参与RISC过程开发高效红色TADF发射器的例子。我们的工作为高性能红色TADF OLED的分子设计策略提供了新的见解。
Accelerating reverse intersystem crossing (RISC) rates of red thermally activated delayed fluorescence (TADF) emitters is crucial yet remains ongoing challenges. Herein, we disclose an ingenious molecular design to dramatically boost such an up-conversion process by leveraging effective participation of localized excited triplet states from both donor and acceptor segments (3LEDand3LEA). Inspiringly, energy level alignment with3LEA-3LEDclose to the charge-transfer singlet and triplet (1CT and3CT) states are obtained in the case of DBBPZ-IDPZ, by simultaneously employing polycyclic large-conjugation donor and acceptor units. Due to the joint contribution of3LEDand3LEA, DBBPZ-IDPZ shows 15.7 folds accelerated RISC rate and delivers a higher photoluminescence quantum yield of 98.1 % relative to the control molecule (36.7 %). Eventually, the red OLED based on DBBPZ-IDPZ presents a significantly improved external quantum efficiency of 26.0 % with an emission maximum at 628 nm, which is approximately triple that of the control device (8.9 %). This is the first example of a delicate management of3LEDand3LEAto simultaneously participate in RISC process for developing highly efficient red TADF emitters. Our work provides new insights into the molecular design tactic of high-performance red TADF OLEDs.