Jiang Chenglin, Miao Jingsheng, Zhang Danwen, Wen Zhenhua, Yang Chuluo, Li Kai
Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518055, China.
College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
Research (Wash D C). 2022 Jun 24;2022:9892802. doi: 10.34133/2022/9892802. eCollection 2022.
Organic push-pull systems featuring through-space charge transfer (TSCT) excited states have been disclosed to be capable of exhibiting thermally activated delayed fluorescence (TADF), but to realize high-efficiency long-wavelength emission still remains a challenge. Herein, we report a series of strongly emissive orange-red and red TSCT-TADF emitters having (quasi)planar and rigid donor and acceptor segments which are placed in close proximity and orientated in a cofacial manner. Emission maxima ( ) of 594-599 nm with photoluminescence quantum yields (PLQYs) of up to 91% and delayed fluorescence lifetimes of down to 4.9 s have been achieved for new acceptor-donor-acceptor (A-D-A) molecules in doped thin films. The presence of multiple acceptors and the strong intramolecular -stacking interactions have been unveiled to be crucial for the efficient low-energy TSCT-TADF emissions. Organic light-emitting diodes (OLEDs) based on the new A-D-A emitters demonstrated electroluminescence with maximum external quantum efficiencies (EQEs) of up to 23.2% for the red TSCT-TADF emitters. An EQE of 18.9% at the brightness of 1000 cd m represents one of the highest values for red TADF OLEDs. This work demonstrates a modular approach for developing high-performance red TADF emitters through engineering through-space interactions, and it may also provide implications to the design of TADF emitter with other colours.
具有通过空间电荷转移（TSCT）激发态的有机推拉体系已被证明能够表现出热激活延迟荧光（TADF），但要实现高效的长波长发射仍然是一个挑战。在此，我们报道了一系列具有（准）平面且刚性的供体和受体片段的强发射橙红色和红色TSCT-TADF发射体，这些片段紧密相邻并以共面方式排列。对于掺杂薄膜中的新型受体-供体-受体（A-D-A）分子，已实现了594-599nm的发射最大值（ ），光致发光量子产率（PLQYs）高达91%，延迟荧光寿命低至4.9s。已发现多个受体的存在以及强分子内 -堆积相互作用对于高效的低能量TSCT-TADF发射至关重要。基于新型A-D-A发射体的有机发光二极管（OLED）显示出电致发光，红色TSCT-TADF发射体的最大外量子效率（EQEs）高达23.2%。在1000cd m亮度下的EQE为18.9%代表了红色TADF OLED的最高值之一。这项工作展示了一种通过设计空间相互作用来开发高性能红色TADF发射体的模块化方法，并且它也可能为其他颜色的TADF发射体的设计提供启示。
