Seed Layer-Assisted Chemical Bath Deposition of CuO Films on ITO-Coated Glass Substrates with Tunable Crystallinity and Morphology

A seed layer-assisted chemical bath deposition (SCBD) method has been developed to create high quality CuO thin films on transparent conductive electrode/glass substrates. A CuO seed layer is formed by the electrodeposition of Cu 2 O on a tin-doped indium oxide (ITO) electrode for 10 s, followed by a brief (15 min) heating step to convert the Cu 2 O to CuO. The seed layer is found to be essential for the growth of micrometer-thick, adherent CuO thin films on ITO-coated glass, as no films were observed to form on substrates without a seed layer. The addition of sodium lactate to the SCBD solution can be used to tune the morphology and relative crystallinity of the CuO films. A highly crystalline CuO film possessing a resistivity of 3.3 × 10 5 Ω·cm has been deposited from a solution without sodium lactate, while a largely amorphous CuO film grown from a solution with a lactate/copper molar ratio equal to 1.0 displayed a resistivity of 7.2 × 10 5 Ω·cm. The CuO film with greater amorphous character exhibited a significantly larger specific capacitance as a redox active electrode compared to the crystalline film (2700 mF/g vs 96 mF/g).