Microstructural properties of an electrochromic WO3 thin film

This is the first report of extended X-ray absorption of fine structure (EXAFS) study on vacuum-evaporated electrochromic WO3 thin film. When monoclinic WO3 powder, the precursor, was evaporated, its long-range order was vigorously destroyed and decomposed into many highly-dispersed clusters. The formed WO3 film, compared to WO3 powder, contracted in W–O distance from 0.138 to 0.136 nm (without phase-shift revised). Its lattice cell further decreased if it was cathodically colored in LiClO4/propylene carbonate solution. Raman measurement during this change process also strongly supported that conclusion.