In-Depth Exploration of the Charge Dynamics in Surface-Passivated ZnO Nanowires

Abstract

One-dimension ZnO nanowires (NWs) are widely used in many optoelectronic devices owing to their high optical transparency and excellent electron-transporting property. Unfortunately, there are various shallow-level and deep-level states in ZnO NWs, which usually act as the charge recombination centers of the devices. Surface passivation is an effective way to reduce deep-level states in ZnO NWs. However, how the surface passivation affects the charge dynamic process in ZnO NWs is still unclear. Herein, we carried out an in-depth study of the charge dynamics in surface-passivated ZnO NWs by using time-resolved photoluminescence and transient absorption spectroscopy techniques. The results show that the percentage of nonradiative recombination in ZnO NWs is efficiently reduced, and the lifetime of photoexcited carrier is increased after surface passivation. The introduction of a thin passivation layer like SnO2 can effectively reduce the rate of interfacial charge recombination without any adverse effect on the electron injection process.