Electrochromic Properties of Sol-gel Deposited V2O5 and TiO2-V2O5 Binary Thin Films

Transparent mixed phase (1 - x)V2O5 -xTiO(2) (x=0,0.1,0.2,0.3,0.4) thin films were prepared on indium tin oxide (ITO) coated glass via sol-gel process. The films were characterized by cyclic voltammetry, optical spectroscopy, scanning electron microscopy, IR and X-ray diffractometer. Electrochemical lithium insertion/extraction showed that the porous structure of sol-gel (1 - x)V2O5-xTiO(2) thin films exhibited good recharge ability of Li+/e(-) insertion/extraction process. For a 220 nm thick (1 - x)V2O5-xTiO(2) film with 90% V2O5, the capacity of charge exchange reached 9 mC/cm(2). In both Li+ intercalated and free states, the films were highly transparent to visible light. Such films have potential applications in counter electrodes for electrochromic smart windows and other electrochemical devices.