Tailoring the photoluminescent property of ZnO/Ag nanocomposite thin films based on a thermal treatment

Abstract

It is a recent hot topic of widespread interest to control the optical properties of metal oxide by noble metal nanoparticles. In this work, ZnO/Ag nanocomposite thin films were prepared by one-step sol-gel method. The crystal phase, morphology of the samples was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The presence of silver nanoparticles was confirmed by transmission electron microscopy (TEM). The distribution and chemical valence state of Ag in the samples was analyzed by elemental mapping images and X-ray photoelectron spectroscopy (XPS), respectively. The optical properties of the samples were studied by UV–visible spectroscopy and photoluminescence. It is found that the thermal treatment temperature has an important effect on the chemical state of silver in ZnO, and the change of chemical state of silver in turn affects the ultraviolet (UV) emission of ZnO. Under an appropriate heating temperature, the doped silver in the ZnO thin film can form silver nanoparticles, and the photoemission transfer of electrons from the silver nanoparticles to ZnO can effectively enhance the UV emission of ZnO thin film. The results show that under the experimental conditions applied in this study, 250°C is an optimum heating temperature, since the ZnO/Ag composite film heated at 250 °C has the strongest UV emission performance.