Fabrication of CuO thin films via Cu ₂ O electrodeposition and subsequent annealing: a potential‐dependent study

The CuO/ITO thin films were fabricated through a two‐step procedure that utilized Cu 2 O electrodeposition and a final annealing step. First, cuprous oxide (Cu 2 O) thin films have been successfully electrodeposited onto indium tin oxide (ITO) substrates. In the electrodeposition process, a solution of copper sulfate (CuSO 4 ) at a concentration of 0.05 M and citric acid at 0.1 M was used, with the solution's pH adjusted to 12. Following this, the Cu 2 O films have been annealed at 500°C for 1 h in air, converting them to cupric oxide (CuO) thin films. By investigating the influence of increasing the deposition potential from −0.4 V to −0.7 V on the structural, morphological, chemical composition, electrical, and optical properties of CuO films, it was found that all films are of p‐type semiconducting nature, having pure monoclinic CuO phase (without impurities), decreased crystallite size (from 21.11 to 14.85 nm), a chemical composition of only Cu and O elements, decreased surface roughness (from 139.41 to 44.53 nm), and increased optical band gap (from 1.56 to 1.82 eV). Moreover, the CuO film obtained at −0.7 V/ECS displayed the highest photocurrent response (−0.25 mA cm −2 ) with the highest stability.