核/壳结构ZnS : Mn/CdS纳米粒子的制备及发光

利用溶剂热法制备了Mn离子掺杂的ZnS纳米粒子(ZnS : Mn),利用沉淀法对ZnS ∶ Mn纳米粒子进行了不同厚度的CdS无机壳层包覆。采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)及光致发光(PL)光谱等手段对样品进行了表征。TEM显示粒子为球形,直径大约在14~18 nm之间。由XRD结果可以看出CdS壳层的形成过程受到了ZnS ∶ Mn核的影响,导致其结晶较差。XRD和XPS测量证明了ZnS : Mn/CdS的核壳结构。随着CdS壳层的增厚,样品的发光强度呈现一直减弱的现象。

Synthesis and Photoluminescent Properties of ZnS : Mn/CdS Nanoparticles with Core/Shell Structure

In nanomaterials science, a great deal of effort has been devoted to the semiconductor nanomate-rials. Research on Ⅱ-Ⅵ semiconductor materials has become a hotspot nowadays, especially in their optical and electric properties. As a kind of luminescent materials, Mn-doped ZnS nanocrystal has drown considerable interests because of its broad potential application prospect, and the luminescent mechanism, preparation method and practical application have been researched deeply. However, the surface states usually act as luminescence quenching centers, causing low luminescent efficiency. There is a large distance for Mn-doped ZnS nanocrystal to application, which is mainly caused by the surface states. Hence, the modification of surface is of crucial importance for the applications of this type of luminescent semiconductor nanomaterials. Among all the surface modification methods, core/shell structure is proved to be a very effective method. In this paper, Mn-doped ZnS nanoparticles synthesized by solvothermal method were successfully coated with CdS shells of various thicknesses by precipitation reaction. The samples were characterized by X-ray diffraction(XRD), transmission electron microscopy images (TEM), X-ray photoelectron spectroscopy (XPS) and the room temperature photoluminescence (PL) spectra. TEM images showed that the nanoparticles are spheric and the average diameter is about 14～18 nm. It was found from the XRD results that the growth of CdS shell is affected by the ZnS:Mn core, resulting in poor crystallinity. The formation of CdS shells on the surface of ZnS:Mn nanoparticles is confirmed by XRD and XPS measurements. As the CdS shell thickened, the Mn emission intensity of ZnS:Mn/CdS nanoparticles shows a gradual decline in the PL spectra.