发光铜纳米团簇在照明和显示领域有着广阔的应用前景. 然而, 发光波长调节的难题极大地限制了其实际应用. 本工作通过溶剂调控的方式在室温条件下成功合成了具有黄色和蓝色发光的铜纳米团簇组装体. 不同溶剂环境导致铜纳米团簇的组装方式不同, 最终形成了两种典型的纳米片和纳米棒组装结构. 组装体中团簇的间距对其发光性能起决定性作用. 该合成方案具有简单易操作和耗时短等优点, 有利于团簇的规模化合成. 此外, 基于合成的金属纳米团簇组装体制备了具有不同发光颜色的发光二极管(LED).

Photoluminescent copper nanoclusters have broad application prospects in lighting and display. However, the difficulty of photoluminescence wavelength regulation greatly limits its practical application. Now, more and more studies show that the photoluminescence of metal nanoclusters cannot be simply attributed to the quantum confinement effect of the metal core, metal-metal, metal-ligand and ligand-ligand interactions play a pivotal role in the emission process. Achieving the effective regulation of these weak interactions in metal nanoclusters is the current research focus in this field. Self-assembly is an effective strategy to regulate these weak interactions in metal nanoclusters. The variation of the spatial assembly structure of metal nanoclusters will affect the charge and energy transfer process, and then affect the photoelectric properties of metal nanoclusters. Although many strategies have been proposed to regulate the assembly structure of metal nanoclusters, most of the proposed strategies need to be carried out under heating conditions, which is not conducive to the large-scale production of metal nanocluster assemblies and limits its practical application. In this paper, copper nanocluster assemblies with yellow and blue emission have been successfully synthesized by a solvent-regulated strategy at room temperature. Different solvent environments lead to different assembly modes of copper nanoclusters, and finally two typical assembly structures of nanosheet and nanorod are formed. In a high boiling solvent, such as dibenzyl ether, the solubility and fluidity of copper clusters are poor, which is conducive to the formation of loose nanosheet assembly structure. In contrast, in a low boiling solvent, such as n-hexane, the solubility and fluidity of copper clusters are better and the clusters tend to form a dense nanorod assembly structure. The spacing of clusters in the assembly plays a pivotal role in its photoluminescence performance. Compared with the single-layer nanosheet structure, the nanorod structure adds the additional interlayer interaction. This results in additional Cu(I)…Cu(I) interaction and the increasing of spacing between adjacent sulfhydryl ligands on the cluster surface. Finally, the emission wavelength of copper nanoclusters blue shifted from ca. 550 nm to ca. 490 nm. This solvent-regulated synthesis strategy is simple, easy to operate and short in time consuming, which is conducive to the large-scale synthesis of copper nanoclusters. In addition, light-emitting diodes (LEDs) with different emission colors based on the synthesized metal nanocluster assemblies were successfully prepared.