Affiliation:
1. School of Physics University of Sydney Sydney NSW 2006 Australia
2. Department of Physics Faculty of Basic Sciences Velayat University Iranshahr Iran
3. School of Biomedical Engineering University of Sydney Sydney NSW 2006 Australia
4. The University of Sydney Nano Institute The University of Sydney Sydney NSW 2006 Australia
5. Charles Perkins Centre University of Sydney Sydney NSW 2006 Australia
6. School of Engineering University of Newcastle Callaghan NSW 2308 Australia
7. Hunter Medical Research Institute (HMRI) Precision Medicine Program New Lambton Heights NSW 2305 Australia
Abstract
Tungsten oxide (WO3) thin films have been of prime interest among electrochromic materials because of their chemical stability, strong adherence to various substrates, and high coloration efficiency. High‐power impulse magnetron sputtering (HiPIMS) holds great potential in fabricating durable WO3‐based electrochromic layers. However, the tungsten target–plasma interactions in reactive‐HiPIMS deposition of WO3 and their role in modulating the electrochromic function of the resulting WO3 coatings are yet to be understood. Herein, by controlling the HiPIMS pulse length, the stoichiometry of tungsten oxide structures can be tuned to optimize the transparency and electrochromic function of the coatings. X‐ray photoelectron spectroscopy data shows that at pulse lengths shorter than 85 μs, the concentration of suboxide compounds is less than that of tungsten trioxide, while for pulse lengths longer than 100 μs, this balance is reversed. The average optical transparency of the coatings in the range of visible light is higher than 80%. The optical transmittance modulation (ΔT) of 38.1, 36.2, and 34.3% and coloration efficiency of 41.3, 38.4, and 35.9 cm2 C−1 are measured for the WOx samples deposited at pulse lengths of 70, 85, and 100 μs, respectively. Tuning the HiPIMS pulse characteristics is a simple strategy to deposit tungsten oxide films with tuned electrochromic properties for an array of applications, from smart windows to wearable displays.
Funder
Australian Research Council