ABSTRACT
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.
ABSTRACT
Electronically tintable windows based on reversible metal electrodeposition are a promising alternative to electrochromic materials due to the high optical contrast imparted by the opacity of thin metal films. While traditional metal-based dynamic windows utilize a metal counter electrode frame, metal electrodeposition on the working electrode must be paired with a plane-parallel counter electrode that facilitates transverse ion migration to enable uniform metal electrodeposition on a large scale. In this manuscript, we develop dynamic windows that combine reversible Bi electrodeposition on the working electrode with a Prussian blue counter electrode that acts as both a charge storage layer that intercalates K+ ions and an anodically coloring material. Since both electrodes darken during window tinting, 25 cm2 devices switch with an optical contrast of â¼67.5% at 700 nm in only 3 s, making them the fastest dynamic windows using reversible metal electrodeposition reported on this scale.
