Electrodeposition and Characterization of Copper Oxide Thin Films for Solar cell Applications

Copper oxide thin films are being considered in thin film solar cells for its unique photovoltaic properties. Electrodeposition is one of the cheapest processes to deposit copper oxide thin films. In this study, copper oxide was electrodeposited on the copper substrate and gold plated glass substrate in an electrolyte bath containing 0.2 M CuSO4.5H2O, 3 M lactic acid and NaOH. A Potentiostat/Galvanostat with silver chloride electrode (Ag/AgCl) as a reference electrode was used for elctrodeposition. During deposition, the bath temperature and pH were maintained 600C and 12-12.5 respectively. Copper oxide was deposited at different potentials and deposition time. The films deposited at different electrodeposition conditions were characterized by Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The optical band gap was determined from the films deposited on gold plated glass substrate using Ultraviolet-Visible Spectroscopy. From visual inspection it was found that copper oxide film was black and adherent on copper substrate. In gold coated glass substrate copper oxide film was also black but bonding between the substrate and copper oxide film was not good. The SEM study reveal that the films become more compact and grain sizes of copper oxide films decreases at more negative potentials in deposition potential range. EDS analysis shows that percentage of oxygen in the copper oxide films increases with more negative potentials at the deposition potential range. It was found that with increase of time more adherent and uniform film thickness occurs. The variation of the thickness of copper oxide films with different deposition parameters was analyzed.