Electrical and electrochemical characterization of poly (ethylene oxide)/V2O5 xerogel electrochromic films

Vanadium pentoxide xerogel films intercalated by poly (ethylene oxide), PEO, were prepared by direct intercalation method via a sol–gel route. The structural properties were investigated using XRD, HRTEM and FTIR analysis. The detailed studies of electrochromic process and their correlation with flatband potentials have been carried out by cyclic voltammograms and Mott–Schottky plots. The electrical properties along and across V–O layers at the heating and cooling process have been evaluated. These results revealed that the insertion of proper amount of PEO can improve the electrochemical properties of V2O5·nH2O films by increasing the electrical conductivity and decreasing the water vapor absorption. Moreover, Mott–Schottky plots verified the electrochromic process, which can be described using the double insertion and extraction mechanism of lithium ions and electrons. The electrochemical impedance spectra verified that PEO/V2O5 electrochromic films favored the kinetics of V4+/V5+ solid-state redox transitions.