Buildings, as significant energy consumers in today's society, have made the promotion of green energy-efficient buildings and the enhancement of energy efficiency upgrades for existing buildings an urgent necessity. Windows, serving as crucial mediators for daylighting and heat exchange in buildings, play a vital role in energy conservation through their optimized selection and design. Traditional windows, while fulfilling daylighting needs, exacerbate indoor temperature rise during hot weather due to their high light transmittance and accelerate heat loss in cold weather due to their high infrared emissivity, forcing buildings to rely heavily on air conditioning and heating systems to maintain comfortable temperatures. Against this backdrop, smart window technology based on photothermal regulatation coatings has emerged as a revolutionary solution to this challenge. These smart windows can intelligently regulate sunlight and heat exchange according to external environmental changes, not only optimizing indoor lighting and thermal comfort but also significantly reducing energy consumption in lighting, heating, and air conditioning systems, thereby contributing to the realization of China's "dual carbon" goals [1-2].
Depending on different external stimuli, smart windows can be mainly classified into electrochromic (EC), photochromic (PC), and thermochromic (TC) smart windows. Among them, EC smart windows are the most widely used. They can actively control the transmittance of materials through electrical signals, featuring high optical modulation, large modulation range, and fast response speed. However, they require intermittent or continuous power supply to operate. PC smart windows, on the other hand, adaptively regulate transmittance using changes in light intensity, with a simple structure and no external energy required, but have limited response speed and regulation range. Therefore, developing electro-optical dual-responsive smart windows that combine the advantages of EC smart windows (active control, large optical modulation, and good reversibility) and PC smart windows (zero energy consumption, adaptive regulation, and good memory effect) is of great theoretical and practical significance. This report introduces an all-solid-state electro-optical dual-responsive smart window with a simple structure, good durability, and flexible regulation methods [3]. By precisely introducing oxygen vacancies and constructing a unique design strategy of heterojunctions, a WO_3-x/ZnO composite film was successfully synthesized, exhibiting remarkable dual flexible regulation characteristics for electricity and light. The first all-solid-state electro-optical dual-responsive smart window based on this composite film can not only automatically sense light intensity to adjust transmittance but also actively regulate through an electric field. Through EC and PC functions, it can achieve significant temperature adjustments of 5.3 and 4.7 °C, respectively, demonstrating its excellent thermal regulation capabilities and energy-saving potential (Figure 1). The introduction of this innovative technology seeks to pave the way for advancing high-performance smart windows, thereby guiding the construction industry towards a more energy-efficient, environmentally friendly, and sustainable future.

References

1. Z. Shao, A. Huang, C. Cao, X. Ji, W. Hu, H. Luo, J. Bell, P. Jin, R. Yang and X. Cao, Nature Sustainability, 2024, 7, 796-803.
2. M. Chen, X. Zhang, D. Yan, J. Deng, W. Sun, Z. Li, Y. Xiao, Z. Ding, J. Zhao and Y. Li, Mater. Horizons, 2023, 10, 2191-2203.
3. M. Chen, X. Zhang, W. Sun, Y. Xiao, H. Zhang, J. Deng, Z. Li, D. Yan, J. Zhao and Y. Li, Nano Energy, 2024, 123, 109352.

Photothermal Regulation Coating;electrochromic;photochromism;smart windows;Dual-response