Facile synthesis of vertically aligned cone-shaped ZnO/ZnS core/shell arrays using the two-step aqueous solution approach

Abstract

Core/shell nanostructures, as an important hybrid structure, exhibit enhanced performances in emission efficiency and high electron mobility, which can be a promising route for practical application of electron field emitters and solar cells. Zinc sulfide (ZnS) is a well-known wide band gap semiconductor that can be regarded as a suitable material for the surface-coating layer on zinc oxide (ZnO) to enhance its luminescent property. In this study, we present, for the first time, a simple two-step aqueous solution approach for the synthesis of well-aligned ZnO)/ZnS core/shell nanocone arrays. Transmission electron microscopy and energy-dispersive X-ray spectroscopy results confirm that the ZnO nanocone arrays are homogeneously coated with the ZnS shell layer. X-ray diffraction patterns of the shelled ZnO nanocone arrays show strong preferred orientation along the c-axis of wurtzite ZnO. Raman spectra of ZnO/ZnS core/shell nanocones indicate a redshift of 5cm−1 for the E2 (high) peak compared with bare ZnO nanocone arrays, which can be attributed to stress induction in the ZnO/ZnS heterostructures. These findings will contribute to the development of novel nanoemitters and solar cells using controllable morphology and suitable shell choice for heterostructures.