Enhanced green photoluminescence and dispersion of ZnO quantum dots shelled by a silica shell

Zinc oxide (ZnO) quantum dots (QDs) stabilized/functionalized with oleic acid and core-shelled with silicon dioxide (SiO₂) are presented. A colloidal route, free surfactant was followed to synthesize ZnO QDs with an average size of 5 nm. After, the ZnO QDs were stabilized with oleic acid to avoid aggregation followed by (3-aminopropyl) trimethoxysilane functionalization. The X-ray diffraction patterns and transmission electron microscopy results indicated that the ZnO QD size and morphology did not suffer any change after functionalization. In addition, the photoluminescence measurements showed a strong green emission band related to particle size and the shell formation. Moreover, the quantum yield and z potential values were determined and the results showed an enhanced for those ZnO@SiO₂ samples with 10 wt% of shell precursor. In this research, we report a high relationship between the stability and photoluminescence properties with the shell precursor concentration. Furthermore, we have developed a reliable method to obtain functionalized ZnO QDs which offer a great potential for future use as photoemission devices such as photonics, photocatalytic activities, biomedicine, optoelectronic devices, and chemical sensing. [Figure not available: see fulltext.]