Liu Zhaoyu, Yao Dong, Ai Lin, Liu Huiwen, Zhang Shitong, Zhang Hao
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
Soft Matter. 2021 May 5;17(17):4550-4558. doi: 10.1039/d1sm00061f.
Fluorescent Cu nanoclusters (NCs) have shown potential in lighting and display, because Cu is cheap and easily available. Despite recent successes in improving the emission intensity of Cu NCs on the basis of aggregation-induced emission enhancement and self-assembly-induced emission enhancement, the difficulty in tuning the emission color sheds the doubt for achieving high-performance white light-emitting diodes (WLEDs). In this work, halogen effects are utilized to tune the emission color of Cu nanocluster self-assembly nanosheets (NSASs). By altering the adsorbed halogens from Cl, Br to I, the emission peak of Cu NSASs is tunable from 495 to 674 nm. In this context, halogen atoms are capable of improving the charge transfer and molecular spin coupling of Cu NCs, and thereby narrow the S0T1 gap and facilitate the intersystem crossing of excitons from a singlet to triplet state. As a result, emission spectra redshift and the population of the exiton recombination via the triplet state pathway is increased, which leads to the improvement of the photoluminescence quantum yield (PLQY). By simply introducing and/or mixing different types of cuprous halides, Cu nanocluster co-assembly nanosheets (NCASs) with full-color emission are obtained. The as-prepared Cu NSASs and NCASs are further employed to fabricate monochrome and white LEDs.
荧光铜纳米团簇（NCs）在照明和显示领域已展现出潜力，因为铜价格低廉且易于获取。尽管近期基于聚集诱导发光增强和自组装诱导发光增强在提高铜纳米团簇的发射强度方面取得了成功，但调节发射颜色的困难对实现高性能白光发光二极管（WLEDs）提出了质疑。在这项工作中，利用卤素效应来调节铜纳米团簇自组装纳米片（NSASs）的发射颜色。通过将吸附的卤素从氯、溴改变为碘，铜纳米片的发射峰可从495纳米调谐至674纳米。在此背景下，卤素原子能够改善铜纳米团簇的电荷转移和分子自旋耦合，从而缩小S0T1能隙并促进激子从单重态到三重态的系间窜越。结果，发射光谱发生红移，并且通过三重态途径的激子复合数量增加，这导致光致发光量子产率（PLQY）提高。通过简单地引入和/或混合不同类型的卤化亚铜，可获得具有全色发射的铜纳米团簇共组装纳米片（NCASs）。所制备的铜纳米片和纳米团簇共组装纳米片进一步用于制造单色和白色发光二极管。
