Effects of oxygen contents on the electrochromic properties of tungsten oxide films prepared by reactive magnetron sputtering

The electrochromism have been extensively investigated due to their potential applications such as smart window of architecture and automobile glazing to save energy and modulate the transmittance of light and solar radiation. The objective of this study is to investigate the effects of sputtering conditions on the microstructure and electrochromic properties of tungsten oxide films prepared by dc reactive magnetron sputtering. Experimental results showed that the deposition rate of WO3−y films decreased with increasing oxygen flow rate. XRD and Raman spectra analysis suggests that the WO3−y films deposited at various oxygen flow rates are poor crystallinity or amorphous. The transmission change between colored and bleached states at a wavelength of 550 nm was 61.4% as the oxygen content was 60%. The coloration efficiency slightly increases with increasing oxygen flow rate in the low oxygen content region and reaching a maximum value of 38.94 cm2/C at 60% oxygen content. In addition, the films deposited at 60% oxygen content showed a good reversibility. The effects of lithium ions intercalated on the transmission of WO3−y films were also discussed.