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 Na 0.33 V 2 O 5 · n H 2 O ( 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 Na 0.33 V 2 O 5 · n H 2 O 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 Na 0.33 V 2 O 5 · n H 2 O thin films in electrochromic devices.