Enhanced photoelectric response of plasmon-active ZnO nanorods by spatial modulation of dielectric environment

Abstract

One-dimensional zinc oxide (ZnO) nanorods have excellent electron mobility and exhibit great potential for photoelectric or photochemical applications. However, poor visible light absorption and rapid surface charge recombination are bottleneck for promoting its applications. In this work, plasmonic gold nanoparticles (Au NPs) and dielectric silicon oxide (SiO2) are deposited on the surface of ZnO nanorods to tune their photoelectric performance. The localized surface plasmon resonance of Au NPs extends the absorption spectrum to visible region. The surface passivation with dielectric SiO2 layer suppresses the photoexcited electron-hole recombination. By rational integration of the configuration, it is found that dielectric spacer (ZnO-SiO2-Au) shows obvious photocurrent improvement. While dielectric shell-coating (ZnO-Au-SiO2) dramatically leads to an outstanding photocurrent enhancement, which is ∼4–28 times higher than that of the other counterparts. The enhanced performance is ascribed to its effectiveness for spatially separating electron-hole pairs and optimizing photo-absorption properties of the metal-semiconductor system. This strategy provides new insights into fabrication of high performance light harvesting antenna, and stands for a basis to design solar-active systems.