Low‐Energy Consumed Switchable Windows with Ultralong Optical Memory via Semiconductor‐Enabled Reversible Zinc Electrodeposition

ABSTRACT Electro‐response switchable windows (ERSWs) can dynamically control light transmission on demand, which showed great application potential for construction of zero‐energy buildings. However, ERSWs' poor bistability compromises their energy efficiency, and the solar heat absorption in dark colored state leads to undesirable parasitic heat re‐emission, thereby diminishing their effectiveness in thermal management. In this work, a bistable reflectance‐modulated electroreflective device based on reversible zinc electrodeposition (ZERD) is designed and prepared to achieve ultra‐low‐power heat management. A dynamic balancing strategy with highly matched potential for the Zn 2 ⁺/Zn redox reaction on both side electrodes gave ZERD excellent bistability (28 days), fast switching (4 s for colored and 8 s for bleached). The reflectance‐modulated property gave ZERD high R sol (64.25%) and low SHGC (0.066), which meant it can reduce parasitic heat re‐emission significantly. Outdoor tests demonstrated reflectance‐modulated ZERD provided enhanced cooling performance compared to transmittance‐modulated ERSW (a maximum temperature reduction of up to 8.4°C). Energy consumption calculations indicated ZERD required only needed to consume up to 0.8% of the total energy savings, while enabling substantial annual energy savings (up to 57.9% in worldwide). The ultralow‐power bistable reflectance‐modulated ZERD offered a valuable strategy for designing high‐performance ERSW and supported progress toward zero‐energy buildings.