利用水溶性前驱体材料在水性介质中制备了ZnS:Mn和ZnS:Mn/ZnS核/壳结构量子点(QDs,quantumdots),并用X射线衍射(XRD)、光致发光(PL)对ZnS:Mn和ZnS:Mn/ZnS核/壳结构QDs的结构和发光性能进行研究。ZnS:Mn和ZnS:Mn/ZnS QDs XRD谱与标准谱吻合,根据Debye-Scherrer公式,ZnS:Mn/ZnS QDs的粒径大于ZnS:Mn QDs的粒径,说明随着ZnS壳层增加,QDs不断生长。在波长325 nm紫外光激发下,ZnS:Mn和ZnS:Mn/ZnS QDs在波长586 nm处均有发射峰,ZnS:Mn/ZnS核/壳结构QDs在波长586 nm处的光发射大幅度增强,且发射峰并未发生红移或蓝移,主要由于包覆ZnS壳层后Mn离子被束缚到ZnS:Mn/ZnS核/壳结构QDs的核内,表面缺陷得到修饰,减少了表面态缺陷能级,阻断了某些无辐射跃迁的通道,增强了ZnS:Mn/ZnS核/壳结构QDs的荧光发射,并构建了发光模型。同时,利用巯基乙酸(TAG)修饰ZnS:Mn和ZnS:Mn/ZnS QDs,改善了其稳定性和水溶性,但是被TAG修饰后ZnS:Mn QDs发光强度大幅下降,ZnS:Mn/ZnSQDs发光强度下降较小。
ZnS:Mn and ZnS:Mn/ZnS core/shell quantum dots(QDs) were prepared in the aqueous medium from readily available precursors.The construction and luminescence properties of ZnS:Mn and ZnS:Mn/ZnS core/shell QDs were evaluated by X-ray diffraction(XRD) and photoluminescence(PL) spectra.The powder X-ray diffraction(XRD) measurements show that the ZnS:Mn and ZnS:Mn/ZnS core/shell QDs are β-ZnS structure,and the size of ZnS:Mn/ZnS core/shell QDs increases with adding ZnS shells.ZnS:Mn and ZnS:Mn/ZnS core/shell QDs both have photoluminescence at 586 nm through the 4T1-6A1 transition of Mn ions.Specially,the PL intensity of ZnS:Mn/ZnS core/shell QDs is enhanced with adding ZnS shells,and ZnS shells never lead to blue or red shift in PL spectra.It is because ZnS shells can block some non-radiative recombination routes related to the surface state of the QDs,which will increase the concentration of luminescent center and decrease the non-radiative recombination sites.The luminescence intensity of thioglycolic acid(TAG) modified ZnS:Mn QDs decreases significantly,while that of thioglycolic acid modified ZnS:Mn/ZnS QDs decreases slightly,although the stability and solubility of thioglycolic acid modified ZnS:Mn and ZnS:Mn/ZnS QDs are improved.