Nanotech 2010

Hollow and Ordered Urchin-like ZnO structures by Novel Electrodeposition Method

J. Elias, C. Lévy-Clément, M. Bechelany, J. Michler, G. Wang, Z. Wang, L. Philippe
Empa - Materials Science & Technology, CH

Keywords: ZnO, Electrodeposition, natural lithography, nanostructured solar cells

Abstract:

In this contribution, we will present an original approach to fabricate, in a time period compatible with large-scale production, thin films composed of well-ordered hollow urchin-like ZnO nanowires (NWs) with controlled NW and core dimensions. The synthesis method combines together the formation of a polystyrene (PS) microspheres colloidal mono/multilayer and the electrodeposition of ZnO NWs, followed by the elimination of the PS microspheres, which play the role of a template. It is shown for the first time that a compound can be electrodeposited on the surface of polystyrene spheres. The key point is to render the PS spheres electrically active by a treatment in a solution of ZnCl2 at high concentration. We also show that the same process allows to deposit multilayers of ZnO urchins on transparent conductive oxide substrates. The urchins have a hollow core covered by free standing single crystal NWs. The dimension of the NWs can be controlled by varying the constitution of the electrolyte. The urchin-like ZnO thin films exhibit a dramatic improvement of the light scattering in the visible which make them very attractive for application as building-blocks in different types of nanostructured solar cells (organic, hybrid and dye sensitized solar cells) and in a wide variety of applications in optical devices, photonic crystals, and nanodevices. The physical properties of the ZnO structures were investigated by Transmission Electron Microscopy (TEM) and Optical Spectroscopy.
 
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