硫脲修饰ZnSe:Cu量子点的水相合成及荧光特性

以3-巯基丙酸为稳定剂在水相中合成了Cu掺杂的ZnSe量子点(QDs), 并利用硫脲(CH₄N₂S)对其进行表面修饰, 制备出核壳结构的ZnSe:Cu/ZnS 量子点. 制得的量子点呈闪锌矿结构, 尺寸约为5 nm, 有较好的分散性, 其荧光发射峰在460 nm左右. 经CH₄N₂S修饰后, 量子点表面形成了宽禁带的ZnS包覆层, 将电子和空穴限域在了ZnSe:Cu 核内, 减少了表面发生非辐射复合的载流子, 显著提高了量子点的荧光强度. 与Na₂S、硫代乙酰胺(TAA)等常用硫源相比, 以CH₄N₂S为硫源制得的ZnSe:Cu/ZnS 量子点壳层厚度可控, 表面钝化效果更好, 显示出更佳的荧光效率和稳定性. ZnSe:Cu/ZnS 量子点经过紫外线照射后消除了表面的悬空键, 进一步提高了其量子产率, 最终获到了具有较好荧光性质的ZnSe:Cu/ZnS量子点.

Preparation and Fluorescence Properties of Aqueous Soluble Thiourea Modified ZnSe:Cu Quantum Dots

Aqueous phase Cu doped ZnSe (ZnSe:Cu) quantum dots (QDs) stabilized with mercaptopropionic acid were prepared, and thiourea was used as a surface modifier to obtain core-shell ZnSe:Cu/ZnS QDs. QDs had a sphalerite structure, were uniformly dispersed, had an average particle size of approximately 5 nm and an emission peak at around 460 nm. After thiourea modification, a wide band-gap ZnS shell was coated on the QDs to passivate the surface, reduce surface states, and significantly improve fluorescence intensity. Thiourea modified ZnSe:Cu/ZnS QDs exhibit better surface passivation, fluorescence efficiency, and stability than those of other surface modifiers like Na₂S and thioacetamide. Quantum yields were further improved after UV irradiation eliminated surface dangling bonds.