Impact of Zr precursor on the electrochemical properties of V2O5 sol-gel films

In this work, we explore the impact of Zr precursor on the electrochemical and optical properties of V2O5 thin films. These films were synthesized by the combination of the sol-gel route with dip-coating deposition on the electron conducting (fluorine tin oxide; FTO) substrate. We used vanadium oxytriisopropoxide (V) - [OV(OC3H7)(3)] and zirconium isopropoxide (IV) - [Zr(OCH2CH2CH3)(4)] as precursors, isopropanol as solvent, and glacial acetic acid as a catalyst. After the deposition, the thin films were subjected to densification at 350 degrees C for 30 min. We characterized these films by electrochemical techniques (cyclic voltammetry, chronoamperometry and chronocoulometry) and we obtained the best result of the load density of 109 mC.cm(-2) for V2O5 sample prepared with 5 mol% of Zr precursor; this sample also presented satisfactory responses of cyclic stability. We used atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) to obtain morphology and crystallinity of this film. Its optical properties, we studied by UV-vis spectroscopy and the transmittance results were of 82% for the discolored and 39% for colored states, both measured at 633 nm. In summary, we show that V2O5:ZrO2 thin films have quite attractive properties for their application as a working electrode in electrochromic devices.