Potential Gradient-Driven Fast-Switching Electrochromic Device

Electrochromic (EC) smart windows are considered one promising energy-conservation and emission-reduction device for green construction. However, conventional EC devices need external power to switch colors, which causes additional energy consumption. Herein, we propose a potential gradient strategy to attain a fast self-chargeable and -dischargeable EC system. In this strategy, the potential difference between Prussian blue (PB) and zinc (Zn) is established to reduce PB to Prussian white (PW) in 1.0 s, while etched carbon paper (ECP) could oxidize PW to its original state in 2.2 s. Moreover, this strategy is shown to be applicable for other high-performance EC systems, including Zn||WO3||ECP, Zn||PEDOT||ECP, Al||PB||ECP, and Zn||PB||ZnHCF. The potential application of large-scale windows is discussed in terms of a prototype 25 cm2 EC window. Thus, the unique potential gradient strategy provides new insights for developing a fast self-switching EC device, which exhibits great application prospects in both energy conservation and energy storage.