Electrodeposition of ZnO thin films on conducting flexible substrates

In this work, we studied the DC electrochemical deposition of zinc oxide (ZnO) thin films on a conducting and flexible substrate, for their application in energy harvesting piezoelectric nanodevices. The deposition process was performed by varying the zinc nitrate concentration (c) in the electrolyte, its temperature (T), and the applied deposition potential (V), and subsequently tracing the influence of such parameters on the morphology (analyzed by scanning electron microscopy), crystallography (X-ray diffraction), and thickness (using the deposition current transient curves) of the ZnO thin films. The variation of the electrodeposition parameters led to the formation of different micro- and nano-structures, such as flat layers, microflowers, nanospheres, webs, and microramifications. Furthermore, the analysis of the deposited charge (by integrating the deposition current transients) illustrated an increase in the deposition rate with the increase of T and c, and a decrease of V. Finally, the maximum ZnO film thickness (~5 \(\upmu {\mathrm{m}}\)) was obtained for T = 80 °C, c = 0.1 M, and V = −1.5 V. This study provides us important tools to tune the electrochemical growth of ZnO thin films.