Low-Energy Consumed Switchable Windows with Ultralong Optical Memory via Semiconductor-Enabled Reversible Zinc...

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 Zn²⁺/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.