Effect of Co Doping on the Functional Properties of MnO2 Thin Films

Thin films of Co-doped [Formula: see text]-MnO2 have been deposited on Pyrex glass substrates by the sol–gel dip-coating method with Co concentrations of 1, 3, 5 and 7 at.%. The deposited thin films were characterized for their structural, morphological, optical and electrical properties. The XRD spectra confirm that all the samples have tetragonal phase of [Formula: see text]-MnO2. FTIR spectra reveal the presence of Mn–O in all of the samples. AFM measurements indicate that the surfaces of films have been affected with cobalt content incorporation. Transmittance spectra of the undoped and Co-doped MnO2 thin films were recorded by a UV–vis spectrometer. Optical gap was found to be in the 2.60–2.51-eV scale. This decrease is due to the presence of manganese vacancies and/or oxygen defects. From the complex impedance measurements that show semicircular arcs at different cobalt contents, an equivalent parallel [Formula: see text] electrical circuit has been proposed.