Analysis of optical dispersion parameters and electrochromic properties of manganese-doped Co₃O₄ dendrite structured thin films

Nebulized spray pyrolysis method was employed to deposit pristine and manganese (Mn) -doped Co₃O₄ thin films for different Mn concentrations (4, 6 and 8 at.%). The structural properties revealed that the obtained films show predominant orientation along (311) plane and significant peak shift was observed upon an increase in Mn doping confirms the substitution of Mn in Co₃O₄ lattice. The pristine Co₃O₄ film shows clustered grains and dendrite patterns appearing with the increase in Mn content as evident from SEM studies. The optical dispersion parameters of the prepared films of pristine and Mn doped Co₃O₄ films were determined from UV transmission spectra. The phase purity and elemental analysis of the films revealed single phase with better stoichiometric films were obtained. The XPS core level spectra of 6 at.% Mn doped Co₃O₄ films exhibited the presence of two different oxidation states (Mn²⁺ and Mn³⁺). The electrical resistivity of the films decreased with increase in Mn dopant concentration was observed from linear four probe method. The Co₃O₄ film deposited using 6 at.% of Mn exhibited a maximum optical modulation of 35% and coloration efficiency of 29 cm²/C.