Effect of Solution pH on Properties of Cuprous Oxide Thin Films Prepared by Electrodeposition from a New Bath

Cuprous oxide (Cu2O) thin films have been successfully electrodeposited onto indium tin oxide-coated glass substrates from copper acetate solution and characterized by x-ray diffraction analysis, scanning electron microscopy, ultraviolet-visible (UV-Vis) spectroscopy, and photoelectrochemical (PEC) and electrical Hall-effect measurements. The effect of the solution pH on the structural, morphological, optical, PEC, and electrical properties of the deposited Cu2O thin films was investigated. The x-ray diffraction results indicated that the prepared Cu2O films exhibited good crystallinity with pure cubic structure, while the crystallite size increased with increasing solution pH. The preferential orientation of the deposited films also changed with the pH value. When the solution pH was changed, the surface morphology changed from spherical to pyramidal shape with increasing grain size. The optical characteristics of the Cu2O thin films were not significantly affected by changing the solution pH value. PEC measurements revealed that Cu2O thin films prepared at pH 6.2 exhibited n-type conductivity, while those obtained at pH 11 showed p-type conductivity. These results were confirmed by Hall-effect measurements. The obtained Cu2O thin films would be promising semiconductor materials for use in various applications such as PEC cells and photovoltaic solar cells.