Stabilized blue emitting ZnS@SiO2 quantum dots

Abstract

As synthetized, zinc sulfide (ZnS) quantum dots have very interesting optical properties, such as a high intensity blue emission band. However, they also present a gradual degradation phenomenon dependent on the time under ultraviolet light exposure, called photo corrosion, where the optical properties of the material are severely affected. The photo corrosion process of ZnS quantum dots occurs under UV light exposure and in presence of the environmental humidity and temperature conditions. In order to avoid the degradation of the material, it is proposed to isolate the surface of the particles by protecting them from the environment with a silicon dioxide (SiO2) coating. This coating results in a higher intensity and stable blue light emission. Unlike most of the reported work, the development of this work was carried out following a simple, low temperature and low toxicity synthesis processes, obtaining the desired material with good optical characteristics. The stabilization of the optical properties of the ZnS quantum dots, brings the possibility to be used to develop long-term optical applications, such as UV to visible light conversion for illumination devices or solar cell's efficiency improvement.