Photoelectrochemical Behavior of Electrodeposited CuO and Cu[sub 2]O Thin Films on Conducting Substrates

Abstract

Cuprous oxide has been prepared by the photoelectrochemical reduction of a CuO film formed on a conducting substrate by the anodic deposition from an alkaline solution of a Cu(II)-amino acid complex. Both copper oxide films thus prepared are found to be typical p-type semiconductors. The onset of the cathodic photocurrent due to the reduction of O2O2 on CuO/ITO (ITO, indium tin oxide) and Cu2O/ITOCu2O/ITO electrodes give positive shifts of about 0.2 and 0.03 V, respectively, from the dark current rises. Optical bandgap energies of CuO films depend on the amino acids used, 1.56 (glycine), 1.40 (alanine), 1.38 (isoleucine), 1.38 eV (valine), and the value of EgEg for the Cu2OCu2O film is 2.17 eV. The relationship between the flatband potential (VFB)(VFB) and the pH for CuO and Cu2OCu2O films are both linear with the slope of about −60 mV/pH in agreement with the Nernstian expression for the VFBVFB of a semiconductor. © 2004 The Electrochemical Society. All rights reserved.