Electrochromic thin films of sodium intercalated vanadium(V) oxide xerogels: Chemical bath deposition and characterization

An optimized chemical bath method is applied to obtain well-structured thin films with composition Na0.33V2O5·nH2O (n = 1 and 1.3). The method is based on a controlled precipitation reaction that takes place in the system of sodium metavanadate and diethyl sulfate at 85 °C. The film structure, morphology and the changes occurring during prolonged aging are examined by XRD, IR spectroscopy, TG-DTA, SEM and AFM. The electrochemical and electrochromic properties are studied by cyclic voltammetry and UV–vis spectroscopy. The as-deposited thin films are characterized with high optical transmittance varying between 40 and 70% at the 500 nm visible region in dependence on film thickness. The Na0.33V2O5·nH2O thin films exhibit stable electrochemical cycling combined with relatively high electrochromic activity. The reproducibility of the transmittance variance of 55% after 500 cycles in the electrochromic cell is a promising result for the potential application of Na0.33V2O5·nH2O thin films in electrochromic devices.