Structural and optical properties of ZnS/ZnO core/shell nanowires grown on ITO glass

ZnO@ZnS core/shell nanowires have been synthesized by an easy conversion process from ZnO nanowire precursors. Firstly, vertically aligned ZnO nanowires approximately 3 Am long and 200 nm in diameter were electrodeposited on an ITO-coated glass substrate. The surface of these wires was then converted into ZnS by immersion in an aqueous Na2S solution. After rigorous water and alcohol washing and air drying, the resulting hybrids were investigated by UV-visible absorption and photoluminescence spectroscopies. These showed an additional band in the visible region which cannot be attributed to the ZnO or ZnS band-gaps, but to a type-II interfacial transition between the valence band of ZnS and the conduction band of ZnO. This proves the relevance of the ZnO@ZnS/ITO nanostructures to potential solar cell applications. (C) 2014 Elsevier B.V. All rights reserved.