Infrared Electrochromic Property of the Colorful Tungsten Oxide Films

Electrochromic materials are capable in a dynamically modulation over their absorption, transmission, reflection and emissivity covering the visible and infrared regions, which is recognized as one of the most effective strategies for an artificial control over the optical spectrum. In practical devices, the modulations for color (visible light) and heat (near-infrared irradiation) are both in demand, and thus it is of significant importance to achieve the dual-band control within single electrochromic device. However, the present design of electrochromic materials mainly focuses on the adjustment ability of visible spectrum or color transformation, while leaving the modulation of infrared spectra often negligible. In this study, a multi-color tungsten oxide film with F-P cavity structure is selected to explore the wide-spectrum electrochromism of visible and infrared spectral regions. The tungsten oxide film material with F-P cavity structure presents diversified and bright colors in the visible region with various color patterns, and diversified color alternation can be realized under applied biases. At the same time, the infrared reflectance of colorful tungsten oxide films can also be modulated significantly, for example, infrared modulation rates higher than 25.00% can be obtained in the middle wavelength (around 3.5 mu m) in the colored films. The research shows that the multi-color tungsten oxide film can realize the discrete and controllable adjustment of the visible and infrared spectral region in the wide spectrum, and has great potential in the application of smart window, thermal management, radiative cooling and other fields, which can even achieve the in-demand cooperative modulation of light and heat performance.

Automated summary

The study demonstrates that the multi-color tungsten oxide film can achieve discrete and controllable adjustment of the visible and infrared spectral region in a wide spectrum, showing great potential in smart windows, thermal management, radiative cooling, and other fields. The colorful tungsten oxide films not only present diversified colors in the visible region, but also significantly modulate the infrared reflectance, achieving infrared modulation rates higher than 25.00% in the colored films.