Low-temperature V-oxide film for a flexible electrochromic device: Comparison of its electrochromic, IR and Raman properties to those of a crystalline V2O5 film

摘要

Manufacturing of flexible electrochromic (EC) devices requires the use of low-temperature films for deposition on electronically conductive foils. With this aim, low-temperature V-oxide films were spin-coated from a dispersion prepared by milling of crystalline V2O5 powder in vanadium(V) tri-n-propoxide oxide/isopropanol sol as dispersant. TEM images showed that the milling procedure enables the introduction of some V2O5 nanocrystallites into the matrix of the V-oxide pigmented film prepared at 150 degrees C. The electrochromic properties were analyzed using in situ UV-visible absorbance spectroelectrochemistry. The low transmittance values of as-prepared pigmented films revealed the presence of a greater amount of reduced V4+ centers compared to the crystalline sol-gel V2O5 model films. Significant bleaching of pigmented V-oxide films occurred during subsequent 521 cycles in the safe potential range.