Interfacial optimization of quantum dot and silica hybrid nanocomposite for simultaneous enhancement of fluorescence retention and stability

Abstract

We have demonstrated an improved quantum dot (QD) and silica hybrid nanocomposite by interfacial optimization for simultaneous enhancement of fluorescence retention and stability. This nanocomposite was synthesized by using silica spheres as cores, adsorbing gradient alloy QDs (GA-QDs) as the first shell, and then coating a silica layer as the other outmost shell (termed SiO2-GA-QD-SiO2). The retaining ratio of pristine fluorescence intensity after silica coating was found to be significantly improved by the QDs' shell interfacial optimization due to the suppression of surface defects. The mechanism of the QDs' surface trap states capturing the excitons before and after silica coating was analyzed in detail. The results show that the optimized SiO2-GA-QD-SiO2 nanocomposite provides the highest resulting fluorescence intensity of 70%, which is 62% and 33% higher than those of the other two conventional structures. Photoluminescent liquid crystal display backlight samples were prepared with this hybrid nanocomposite to show the robustness against high temperature and humid environment. Even when immersed in water and heated to 80 °C, the backlight samples still retained 85% of the initial fluorescence, which was 40% higher than that with bare GA-QDs. High fluorescence and long-term stability highlight the potential of using this nanocomposite in displays or lighting applications.