Zhang Nan, Qu Lei, Hu Huan, Huo Ran, Meng Yushan, Duan Chunbo, Zhang Jing, Han Chunmiao, Xie Guohua, Xu Hui
Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Material Science, Heilongjiang University, 74 Xuefu Road, Harbin 150080, P. R. China.
Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, P. R. China.
Research (Wash D C). 2022 Dec 15;2022:0005. doi: 10.34133/research.0005. eCollection 2022.
Controllably optimizing excited-state characteristics is crucial for luminescent nanoclusters but remains a formidable challenge. Herein, we report an effective "ligand-induced asymmetrization" strategy for constructing thermally activated delayed fluorescence-featured cubic CuI nanoclusters with asymmetric configurations, named [tBCzDBFDP]CuI and [PTZDBFDP]CuI. Through changing 3,6-di--butyl-carbazole (tBCz) to phenothiazine (PTZ) with a stronger electron-donating effect, emission color is tuned from greenish blue of [tBCzDBFDP]CuI to yellow of [PTZDBFDP]CuI, as well as the triplet locally excited state of the former to the triplet charge transfer state of the latter. Temperature-correlated spectroscopic investigation indicates that in terms of triplet quenching suppression, [tBCzDBFDP]CuI is superior to [PTZDBFDP]CuI, in accord with the stabilities of their triplet locally excited state and triplet charge transfer state. As a consequence, these asymmetric CuI nanocubes endowed their cluster light-emitting diodes with the external quantum efficiencies beyond 12% for sky blue and 8% for yellow. These results suggest the significance and effectiveness of ligand engineering for optoelectronic nanoclusters.
可控地优化激发态特性对于发光纳米团簇至关重要，但仍然是一项艰巨的挑战。在此，我们报告了一种有效的“配体诱导不对称化”策略，用于构建具有不对称构型的热激活延迟荧光特性的立方碘化亚铜纳米团簇，命名为[tBCzDBFDP]CuI和[PTZDBFDP]CuI。通过将具有较强供电子效应的3,6-二丁基咔唑（tBCz）换成吩噻嗪（PTZ），发射颜色从[tBCzDBFDP]CuI的蓝绿色调至[PTZDBFDP]CuI的黄色调，同时前者的三重态局域激发态转变为后者的三重态电荷转移态。温度相关的光谱研究表明，在三重态猝灭抑制方面，[tBCzDBFDP]CuI优于[PTZDBFDP]CuI，这与它们的三重态局域激发态和三重态电荷转移态的稳定性一致。因此，这些不对称的碘化亚铜纳米立方体赋予其团簇发光二极管的外量子效率，天蓝色超过12%，黄色超过8%。这些结果表明了配体工程对光电子纳米团簇的重要性和有效性。
