Synthesis of needle-shape ZnO-ZnS core-shell heterostructures and their optical and field emission properties

Abstract

Well-aligned ZnO-ZnS core-shell nano-needle arrays were synthesized using a simple aqueous solution approach to investigate the optical and field emission properties of heterostructure materials. The photoluminescence of the core-shell nano-needles exhibits a distinct enhancement compared with that of uncoated ZnO nano-needles. The UV-vis spectra show that the ZnS shell layer enhances the optical absorption of ZnO nano-needles by decreasing the interface band gap, which indicates the potential application of heterostructures in photovoltaic and solar cells. The core-shell nano-needles exhibit a remarkably high field enhancement factor of 3.74 × 103, a low turn-on field of 2.31 V/μm, and a high time stability. These findings show that the construction of core-shell heterostructure can efficiently improve the field emission performance of ZnO nano-needles, which is a promising route for the development of novel nanoemitters with controllable morphology and as suitable shell materials for heterostructures.