Electrochemical Proton Intercalation in Vanadium Pentoxide Thin Films and its Electrochromic Behavior in the near-IR Region

This work examines the proton intercalation in vanadium pentoxide (V₂ O₅ ) thin films and its optical properties in the near-infrared (near-IR) region. Samples were prepared via direct current magnetron sputter deposition and cyclic voltammetry was used to characterize the insertion and extraction behavior of protons in V₂ O₅ in a trifluoroacetic acid containing electrolyte. With the same setup chronopotentiometry was done to intercalate a well-defined number of protons in the H_x V₂ O₅ system in the range of x=0 and x=1. These films were characterized with optical reflectometry in the near-IR region (between 700 and 1700 nm wavelength) and the refractive index n and extinction coefficient k were determined using Cauchy's dispersion model. The results show a clear correlation between proton concentration and n and k.