OPTICAL CHARACTERIZATIONS OF CdS/ZnS AND CdS/ZnS/SiO2 NANOPARTICLES FOR LABELLING APPLICATIONS

Abstract

Semiconductor compounds of the A^IIB^VI group have long been the subject of research interest in the fabrication of nanomaterials. For application purposes, semiconductor nanoparticles or quantum dots based on these semiconductors are often fabricated as core/shell structures to increase fluorescence efficiency. Adding a silica shell to these nanoparticles will limit the flicker fluorescence and toxicity of the quantum dots, further expanding the biocompatibility for marker applications. In this study, colloidal CdS/ZnS nanoparticles were fabricated directly in an aqueous medium for fluorescence emission in the blue region. The CdS/ZnS/SiO₂ nanoparticles were then prepared by silica coating for the CdS/ZnS nanoparticles via the Stöber method. The fluorescence intensity of CdS/ZnS/SiO₂ nanoparticles depends on the formation of a SiO₂ shell surrounding the CdS/ZnS nanoparticles or on the catalyst present in the reaction. The luminescence lifetime of CdS/ZnS/SiO₂ nanoparticles was determined to be longer than that of CdS/ZnS nanoparticles, which is suitable for marker applications.