核壳型ZnS∶Cu/ZnS量子点的制备及发光性质

Synthesis and Photoluminescent Properties of Core/Shell Structure ZnS∶Cu/ZnS Quantum Dots

本文采用水相合成方法制备了ZnS∶Cu量子点并进行了ZnS壳层修饰,研究了壳层厚度对ZnS∶Cu量子点光学性质的影响,采用TEM、XRD、PL、PLE和UV-Vis等测试方法对其进行了表征。实验结果表明,合成的ZnS∶Cu/ZnS量子点为立方闪锌矿,尺寸分布均匀呈球形,分散性良好,经过壳层修饰平均粒径由2 nm增加到3.2 nm。随着ZnS壳与ZnS核量的比的增加,量子点的PLE激发峰位置和UV-Vis吸收谱线出现红移,也说明了量子点的尺寸增大,证明ZnS在ZnS∶Cu量子点的表面生长,形成了核壳结构的ZnS∶Cu/ZnS量子点。随着壳层增厚,量子点与铜离子发光中心相关的发射峰强度先增大后减小,当壳核比ns/nc=2.5时,发光强度达到最大。

ZnS∶Cu quantum dots have been synthesised via a water-soluble route,then the ZnS shell coated for surface modification.The influence of shell thickness on the optical properties of ZnS∶Cu quantum dots has been studied.The samples were characterized by TEM,XRD,PL,PLE and UV-Vis.The results showed that the ZnS∶Cu/ZnS quantum dots were cubic sphalerite,uniform spherical-shaped and had a narrow size distribution.The average particals size increased from 2 nm to 3.2 nm after the shell modification.The PLE and UV-Vis spectra showed a gradual red shift with the shell thickening,which suggested that the quantum dots was growing with the ns/nc increased.It can proved that the ZnS shell growed on the ZnS∶Cu quantum dots surface and formed the ZnS∶Cu/ZnS core/shell structure quantum dots.The PL intensity related with Cu2＋ increased at the beginning and decreased with further growth of the ZnS shell.The intensity of emission peak achieved the maximum when ns/nc=2.5.