Effect of UV Irradiation on Optical Properties of Water-Based Synthetic Zinc Selenide Quantum Dots

Abstract

ZnSe quantum-dots were synthesized in an aqueous system and UV irradiation was introduced as a post-treatment process. The synthesis temperature was varied from 25 oC to 90 oC, and the surface of the nano powder was stabilized using different ligands such as glutathione (GSH), 3-mercaptopropionic acid (MPA) and thioglycolic acid (TGA). Then, the effect of UV irradiation on the structure and the absorption/ emission properties of the nano powder were investigated. As the UV light was irradiated, the PL intensity of the quantum dots increased. UV irradiation for 16 h increased the PL intensity of the synthesized quantum dots at room temperature to the level of those at 90 oC. Particle aggregation was not found with UV irradiation of at least 24 h. XRD patterns confirmed that the UV irradiation released sulfur from the GSH, inducing the formation of the ZnSe/ZnS composite-typed nano powders. The luminescence characteristics of the GSH or TGA-added quantum dots were enhanced by UV irradiation regardless of temperature, while MPA-added quantum dots were not significantly affected by UV irradiation. The post-treatment process with UV irradiation showed the possibility that even ZnSe quantum dots, which are synthesized at low temperature and have low luminescence intensity, can have luminescence characteristics comparable to those of high-temperature synthesis.