Nb2O5 electrochromic films were produced by the Pechini method and deposited by dip-coating. The influence of the preparation conditions on the materials properties was investigated by a fractional factorial design based on eight variables. The films had their electrochromic properties investigated by cyclic voltammetry and UV-Vis spectrophotometry "in situ", in acetonitrile solution containing LiClO4 0.1 M as supporting electrolyte . During the reduction, a blue coloration is formed in the Nb2O5 electrode. This coloration process is associated to the Nb5+ to Nb4+ reduction and the intercalation of Li+ ions. A density charge of 45 mC/cm2 was obtained during cathodic sweeping at v=10 mV/s. The same film showed good optical reversibility, with variation of transmittance of approximately 60%. X-Ray diffraction reveals that the films which presented best electrochromic response are those that possess higher crystalline character.
niobium oxide; electrochromism; factorial design
