Hydrothermally grown nanostructured WO3 films and their electrochromic characteristics

We report the synthesis of nanostructured tungsten trioxide (WO3) films and their electrochromic characteristics. Plate-like monoclinic WO3 nanostructures were grown directly on fluorine-doped tin oxide glass substrates by a simple and low-cost crystal-seed-assisted hydrothermal method. The growth mechanism of the film is investigated. HRTEM analysis reveals the single crystalline quality of the WO3 nanostructure. The film exhibits tunable transmittance modulation under different voltages and repetitive cycling between the clear and blue states has no deleterious effect on its electrochromic performance after 3000 cycles. The electrochromic device composed of the WO3 film has high electrochromic stability, colour contrast and reasonable switching response with a colouration efficiency of 38.2 cm2 C-1 at 632.8 nm.