红色荧/磷光的Cu掺杂Zn-E-E'(E和E'=S,Se,Te)三元纳米晶的设计合成与应用研究

Red light is very important in such fields as biomedicine and white device. How to design and synthesize red-emitting semiconductor nanocrystals with high quantum efficiency, low cost, and harmless to environment is one of hot and difficult issues in the research area about light-emitting nanomaterials. China has abundant copper reserves, and it is of great theoretical and practical significance to develop Cu-doped light-emitting semiconductor nanocrystals and to further explore new fluorescence/phosphorescence phenomena and application prospects. In this project, the Cu-doped zinc chalcogenide Zn-E-E' (E and E' = S, Se, or Te) ternary semiconductor nanocrystals with red fluorescence/phosphorescence are synthesized by using Cu(I) or Cu(II) ions (both of which are called as "Cu") as the dopant, and Zn-E-E' ternary semiconductor nanocrystals composed of zinc and two kinds of chalcogen elements (E and E') as the matrix, the energy band structure of the Zn-E-E' ternary semiconductor nanocrystals matrix and the Cu level in the matrix are adjusted by the formation of ZnE@ZnE' type-II core-shell nanocrystals or ZnExE'1-x alloyed nanocrystals, and the regulation of particle size and chemical composition (E and E' species, E/E' ratio), which enables the fluorescence/phosphorescence color of zinc chalcogenide nanocrystals to shift to red light region. Then, the morphology and structure characterization as well as property studies of the resulting nanocrystals are also performed. In addition, the Cu-doped Zn-E-E' ternary semiconductor nanocrystals are further functionalized by ligand exchange and the carboxyl-functionalized Cu-doped nanocrystals are used as red fluorescent/phosphorescent probe for quantitative detection of metal ion, tumor cell labeling and in-vivo imaging, which explores possible applications in the fields of analysis and biomedicine.

红光在生物医学和白光器件等领域至关重要。如何设计合成量子效率高、成本低、对环境友好的红光半导体纳米晶是发光纳米材料的研究热点和难点之一。我国铜储量丰富，开发铜掺杂发光半导体纳米晶并挖掘其新发光现象和应用前景有重要的理论和现实意义。本项目以铜（Cu）离子为掺杂离子，以锌（Zn）与两种硫族元素（E和E'=S,Se,Te）组成的Zn-E-E'三元纳米晶为基质，通过形成ZnE@ZnE'-II型核壳纳米晶或ZnExE'1-x合金纳米晶基质，并调控纳米晶的粒径大小和化学组成，从而改变基质的带隙能大小及Cu在基质中的能级位置，获得具有红色荧/磷光的Cu掺杂Zn-E-E'三元纳米晶，使锌硫族纳米晶的发光延伸至红光区。除对样品进行形貌和结构表征以及性质研究外，项目还以羧基功能化的红色荧/磷光Cu掺杂纳米晶为探针开展金属离子的定量检测分析、肿瘤细胞标记和活体成像等研究，探索其在分析和生物医学领域的潜在应用。

与荧光的镉硫族纳米晶相比，锌硫族纳米晶尽管有对环境更友好等优点，但也存在荧光可调控的范围更窄、难以实现黄色和红色荧光等不足。利用储量丰富、价廉、低/无毒的铜(I)或铜(II)进行掺杂是实现锌硫族半导体纳米晶更广泛应用的有效手段之一。因此，设计开发具有红色荧/磷光的Cu掺杂Zn-E-E'（E和E'=S,Se,Te）三元纳米晶是值得关注的课题，有着重要的理论和现实意义。. 项目围绕红色磷光的Cu掺杂Zn-E-E'纳米晶的合成，从各种反应参数的调控出发，首先针对液相法制备硫属化物纳米材料时所需合适的硫属前驱体种类少，尤其缺乏成本低、安全稳定的Te前驱体溶液的现实，找到了几种条件温和简单、普适性强的制备方法和相应的溶剂，进而利用热注入法和溶解热法等合成了一系列Zn-E（ZnSe、ZnTe）二元幻数/常规纳米晶和Zn-E-E'三元纳米晶（ZnSexS1-x、ZnSexTe1-x合金纳米晶和ZnSe@ZnS、ZnSexTe1-x@ZnSe核壳纳米晶），最后以溶剂热和连续离子层吸附与反应等技术形成的ZnSexS1-x和ZnSe@ZnS纳米晶为基质，利用生长掺杂策略制备了Cu掺杂Zn-Se-S三元纳米晶，并进一步研究了卤离子和基质组成对Cu掺杂Zn-Se-S三元纳米晶发光性能的影响，成功实现了Cu掺杂Zn-Se-S三元纳米晶的磷光颜色在蓝→红色范围的调控，优化条件后发蓝绿光的Cu掺杂纳米晶的磷光量子效率最高约34%，红光的磷光量子效率为6.8%。该研究结果为设计合成Zn-E二元纳米晶、Zn-E-E'三元纳米晶和其他Cu铜掺杂Zn-E-E'三元纳米晶以及调控其发光性能提供了新的思路和方法。项目还开发了基于Cu相关纳米粒子的纳米平台并用于肿瘤细胞标记等研究，成功进行了癌症的靶向跟踪和光动力/光热协同疗法治疗，为其在生物医学领域的应用提供了实验基础和理论依据。