Cr doping effect on the structural, optoelectrical and photocatalytic properties of RF sputtered TiO2 thin films from a powder target

In this study, thin films of pure and chromium doped TiO2 were deposited by RF magnetron sputtering technique with recourse to a low cost powder target. The dopant concentration was varied from 0 to 6 wt %. The structural, optical, electrical and photocatalytic properties of the sputtered deposited films were systematically investigated on the basis of the incorporated Cr content. XRD analysis revealed that the elaborated films are polycrystalline and have a preferential orientation along the (110) plane, characteristic of the rutile phase. The optical measurements showed a good homogeneity of the films and a high transmission that reached 85% in the visible range. The high transparency of these films allows their use as an optical window in thin film solar cells. Optical band gap decreased from 3.44 eV to 3.32 eV with the increase of the Cr content. In addition, the impedance spectroscopy analysis showed that the conductivity increases along with increasing frequency and temperature, and that the conduction mechanism follows the correlated barrier hopping model. The test of the catalytic efficiency of the chromium-doped TiO2 thin films at different concentrations demonstrated a degradation of the methylene blue (MB) and an improvement of the photocatalytic activity and that the 6 wt% doped thin films have the best photocatalytic activity. (C) 2020 Elsevier B.V. All rights reserved.