Wang Zhaojin, Zhao Juewen, Muddassir Mohd, Guan Rongfeng, Tao Silu
Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng, Jiangsu Province 224051, P.R. China.
School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, P.R. China.
Inorg Chem. 2021 Apr 5;60(7):4705-4716. doi: 10.1021/acs.inorgchem.0c03664. Epub 2021 Mar 19.
The aggregation-induced emission (AIE) behaviors of carborane-based hybrid emitters have been extensively reported, while their combinations with the thermally activated delayed fluorescence (TADF) are still scarce. We designed and synthesized three Janus carboranes (the chemical structures resemble the double-faced god, Janus) with different carbazole moieties. All of the Janus carboranes exhibited quenched emission in solution with Φ (quantum efficiency of photoluminescence (PL)) lower than 0.01. The PL performance was improved by proceeding to the aggregates in THF/water (Φ 0.17-0.35) and further improved in the crystals or solid with Φ up to 0.99 for -, 0.85 for , and 0.61 for -, which agreed with the AIE enhancement. Although the PL of solid showed non-TADF properties with lifetimes only at several nanoseconds, the crystallographic studies have shown a root cause of π···π stacking that quenched the TADF, and the theoretical calculations forecasted small singlet-triplet energy gaps (Δ) therein. According to these findings, TADF was recovered in by doping into 1,3-bis(carbazol-9-yl)benzene (mCP). The 10 wt % doped films of have achieved a trade-off of Φ (0.84 in - and 0.83 in -) and delayed lifetime (up to 8 μs). The doped devices of organic light-emitting diodes incorporating achieved the highest external quantum efficiency at 10.1% and the maximized luminance of 5920 cd/m at a driving voltage of 8 V.
基于碳硼烷的杂化发光体的聚集诱导发光（AIE）行为已被广泛报道，然而它们与热激活延迟荧光（TADF）的结合仍然很少。我们设计并合成了三种具有不同咔唑部分的双面碳硼烷（化学结构类似于双面神Janus）。所有双面碳硼烷在溶液中均表现出猝灭发射，其Φ（光致发光（PL）量子效率）低于0.01。在四氢呋喃/水中形成聚集体时PL性能得到改善（Φ为0.17 - 0.35），在晶体或固体中进一步改善，对于 - ，Φ高达0.99；对于 ，Φ为0.85；对于 - ，Φ为0.61，这与AIE增强一致。尽管固体 的PL表现出非TADF特性，寿命仅为几纳秒，但晶体学研究表明π···π堆积是猝灭TADF的根本原因，理论计算预测其中单重态 - 三重态能隙（Δ）较小。根据这些发现，通过掺杂到1,3 - 双（咔唑 - 9 - 基）苯（mCP）中，在 中恢复了TADF。 的10 wt％掺杂薄膜实现了Φ（ - 中为0.84， - 中为0.83）和延迟寿命（高达8 μs）的平衡。包含 的有机发光二极管的掺杂器件在驱动电压为8 V时实现了最高10.1％的外量子效率和5920 cd/m的最大亮度。
