Electrochromic performance, wettability and optical study of copper manganese oxide thin films: Effect of annealing temperature

The nanostructured copper manganese oxide (CMO) thin films were prepared by acetate based sol-gel precursors dip-coating method with a Cu(ac)2/Mn(ac)2 molar ratio of 20/80. CMO thin films were deposited on glass and indium tin oxide (ITO) substrates and heat treated in ambient air at 300, 400 and 500 °C and named CMO_3, CMO_4 and CMO_5, respectively. With varying annealing temperature, the surface nature of thin films was changed from hydrophilic (CMO_3, CMO_4) to hydrophobic (CMO_5). The electrochromic performance including the anodic and cathodic charge density and capacitance of CMO electrode calculated by cyclic voltammetry measurements in potential range of −1-1 eV at different scan rates ranging from 10 to 100 mV/s. The annealed CMO thin film at 500 °C with maximum anodic and cathodic charge density and interfacial capacitance showed better electrochromic performance with respect to other electrodes at lower scan rate. Also, the increasing annealing temperature affected on crystal structure, optical constants and optical band gap.