Oxygen-deficient tungsten oxide nanoflowers for dynamically tunable near-infrared light transmittance of smart windows
Ya Huang, Baoshun Wang, Pei Lyu, Siming Zhao, Xueke Wu, Shiliang Zhang, Run Li, Qinyuan Jiang, Fei Wang, Yanlong Zhao, Rufan Zhang
Abstract
Electrochromic smart windows have attracted much attention in energy-saving buildings because of their ability to selectively modulate visible (VIS) and near-infrared (NIR) light transmittance. As is known, the NIR region accounts for about 50% of the total solar radiation. Therefore, reducing the NIR transmittance of windows will play a crucial role in reducing the energy consumption of buildings. However, for most of the reported electrochromic materials (ECMs)-based windows, it remains a long-lasting challenge about how to achieve a low NIR transmittance during the past decades. In this work, we synthesize oxygen-deficient tungsten oxide (WO 3− x ) nanoflowers (NFs) by a simple and efficient method that is facile for their mass production. The WO 3− x NFs exhibit low NIR transmittance of only 4.11%, 0.60%, and 0.19% at 1200, 1600, and 1800 nm, respectively, due to the localized surface plasmon resonance (LSPR) effect. Besides, the WO 3− x NFs exhibit an excellent dual-band modulating ability for both VIS and NIR light. They are able to operate in three distinct modes, including a bright mode, a cool mode, and a dark mode. Moreover, the WO 3− x NFs exhibit a fast bleaching/coloring time (1.54/6.67 s), and excellent cycling stability (97.75% of capacity retention after 4000 s).