At present, inorganic semiconducting materials are the most economical and viable source for the renewable energy industry. The present work deals with the morphological and optical characterization of copper oxide (CuO) and zinc oxide (ZnO) thin films fabricated by layer by layer deposition on nickel oxide (NiO) coated indium tin oxide (ITO) glass by solution processing methods, mainly chemical bath deposition (CBD) and hydrothermal deposition (HTD) processes at room temperature. As a whole, the above inorganic composite materials (NiO/CuO/ZnO) can be applied in photovoltaic cells. An attempt has been made to study structural, morphological and absorption characteristics of NiO/CuO/ZnO heterojunction using state of the art techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV spectroscopy. The energy band gaps of CuO and ZnO have also been calculated and discussed based on the UV spectroscopy measurements.

We have demonstrated hydrothermal synthesis of rectangular pillar-like CuO nanostructures at low temperature (~60°C) by selective growth on top of NiO porous structures film deposited using chemical bath deposition method at room temperature using indium tin oxide (ITO) coated glass plate as a substrate. The growth of CuO not only filled the NiO porous structures but also formed the big nanopillars/nanowalls on top of NiO surface. These nanopillars could have significant use in nanoelectronics devices or can also be used as p-type conducting wires. The present study is limited to the surface morphology studies of the thin nanostructured layers of NiO/CuO composite materials. Structural, morphological, and absorption measurement of the CuO/NiO heterojunction were studied using state-of-the-art techniques like X-ray diffraction (XRD), transmission electron microscopy (SEM), atomic force microscopy (AFM), and UV spectroscopy. The CuO nanopillars/nanowalls have the structure in order of (5 ± 1.0) μm × (2.0 ± 0.3) μm; this will help to provide efficient charge transport in between the different semiconducting layers. The energy band gap of NiO and CuO was also calculated based on UV measurements and discussed.