Fluorescent Metal–Semiconductor Hybrid Structures by Ultrasound-Assisted in Situ Growth of Gold Nanoparticles on Silica-Coated CdSe-Dot/CdS-Rod Nanocrystals

Abstract

Gold nanocrystals (AuNCs) were grown on the surface of silica-coated CdSe-dot/CdS-rod core/shell NCs by reduction of Au3+ ions in polyethylene glycol under ultrasonic irradiation. The polyethylene glycol not only prevents the penetration of gold ions or precursor molecules into the silica shell but also acts as the reducing agent for Au3+ ions. The silica shell’s surface promotes the heterogeneous nucleation of AuNCs, whereas the ultrasonic irradiation accelerates and enhances the gold nucleation on the silica surface and ensures the formation of AuNCs with a relatively narrow size distribution. The plasmon–exciton interaction in these metal–semiconductor hybrid systems leads to decreased fluorescence lifetimes and strongly reduced fluorescence blinking of individual hybrid structures.