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.