Lan Xia, Zeng Jiajie, Chen Jinke, Yang Tao, Dong Xiaobin, Tang Ben Zhong, Zhao Zujin
State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China.
School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China.
Angew Chem Int Ed Engl. 2025 Jan 2;64(1):e202414488. doi: 10.1002/anie.202414488. Epub 2024 Oct 22.
Constructing folded molecular structures is emerging as a promising strategy to develop efficient thermally activated delayed fluorescence (TADF) materials. Most folded TADF materials have V-shaped configurations formed by donors and acceptors linked on carbazole or fluorene bridges. In this work, a facile molecular design strategy is proposed for exploring sandwich-structured molecules, and a series of novel and robust TADF materials with regular U-shaped sandwich conformations are constructed by using 11,12-dihydroindolo[2,3-a]carbazole as bridge, xanthone as acceptor, and dibenzothiophene, dibenzofuran, 9-phenylcarbazole and indolo[3,2,1-JK]carbazole as donors. They hold outstanding thermal stability with ultrahigh decomposition temperatures (556-563 °C), and exhibit fast delayed fluorescence and excellent photoluminescence quantum efficiencies (86 %-97 %). The regular and close stacking of acceptor and donors results in rigidified molecular structures with efficient through-space interaction, which are conducive to suppressing intramolecular motion and reducing reorganized excited-state energy. The organic light-emitting diodes (OLEDs) using them as emitters exhibit excellent electroluminescence performances, with maximum external quantum efficiencies of up to 30.6 %, which is a leading value for the OLEDs based on folded TADF emitters. These results demonstrate the proposed strategy of employing 11,12-dihydroindolo[2,3-a]carbazole as bridge for planar donors and acceptors to construct efficient folded TADF materials is applicable.
构建折叠分子结构正成为开发高效热激活延迟荧光（TADF）材料的一种有前景的策略。大多数折叠TADF材料具有由连接在咔唑或芴桥上的供体和受体形成的V形构型。在这项工作中，提出了一种简便的分子设计策略来探索三明治结构分子，并以11,12-二氢吲哚并[2,3-a]咔唑为桥、呫吨酮为受体、二苯并噻吩、二苯并呋喃、9-苯基咔唑和吲哚并[3,2,1-JK]咔唑为供体构建了一系列具有规则U形三明治构象的新型且稳定的TADF材料。它们具有出色的热稳定性，分解温度超高（556 - 563°C），并表现出快速延迟荧光和优异的光致发光量子效率（86% - 97%）。受体和供体的规则且紧密堆积导致分子结构刚性化，具有有效的空间相互作用，这有利于抑制分子内运动并降低重组激发态能量。以它们作为发光体的有机发光二极管（OLED）表现出优异的电致发光性能，最大外量子效率高达30.6%，这是基于折叠TADF发光体的OLED的领先值。这些结果表明，所提出的以11,12-二氢吲哚并[2,3-a]咔唑为平面供体和受体的桥来构建高效折叠TADF材料的策略是适用的。
