Hybrid Dynamic Windows with Color Neutrality and Fast Switching Using Reversible Metal Electrodeposition and Cobalt Hexacyanoferrate Electrochromism

Dynamic windows, which electronically switch between clear and dark states on demand, save energy in buildings and automobiles by minimizing the lighting, heating, and cooling costs. In this study, we design dynamic windows by combining reversible metal electrodeposition (RME) and electrochromism, two promising approaches for optoelectronics. These hybrid dynamic windows tint on both electrodes. Reversible Bi and Cu electrodeposition is elicited on the working electrode, while an electrochromic cobalt hexacyanoferrate thin film darkens on the counter electrode. By facilitating plane parallel ion diffusion and dual tinting, this architecture enables dynamic windows to switch more rapidly than devices based on traditional RME schemes. We demonstrate that 25 cm2 devices switch with 58% optical contrast between a transparent and a color-neutral dark state in 20 s. Moreover, these hybrid dynamic windows switch 1000 times without significant degradation in optical performance.