Electrochemical deposition of ordered macroporous ZnO on transparent conducting electrodes

Large area macroporous zinc oxide (ZnO) films have been prepared by colloidal crystal templating on to transparent conducting oxide (TCO) substrates using an electrochemical deposition technique. Characterisation by scanning electron microscopy (SEM) reveals changes in the microstructure of the ZnO films as the template diameter and deposition potential are varied. Analysis by X-ray diffraction (XRD) and UV–vis spectroscopy show that the structural variations do not influence the inherent properties of the ZnO. We attribute the observed microsturctural differences to variations in growth kinetics in response to the applied deposition potential and solution transport phenomena that are controlled by the template dimensions. The optical properties of the structures exhibit two distinct features, originating from the optical band-gap of the ZnO and the photonic band-gap of the ordered macroporous structure.