UV‐Activated Large‐Area Switchable Electro‐Reflective Window for Energy‐Efficient Electric Vehicles

The development of electrically driven smart glass with controlled modulation of solar radiation provides a reliable solution to seasonal fluctuations in cabin temperature, privacy leakage, and range anxiety in electric vehicles. However, the preparation of large‐area electrochromic glass for cooling in summer and heating in winter remains a challenging task. Here, an electro‐reflective device (ERD) with solar reflectance of 0.808 in the mirror state and solar transmittance of 0.637 in the transparent state is obtained by simple UV‐activated operation of the device with a three‐layer structure (ITO glass/electrolyte/ITO glass). The UV activation promotes the electrodeposition of finer, denser metal particles, reduces the electrodeposition voltage of Ag + by 29.2% and improves the light transmittance in the transparent state, which provides conditions for the expansion of the working area (up to 1726 cm 2 ) and the enhancement of the seasonal temperature control. Simulation results show that ERD has achieved energy savings in air conditioning systems globally, with annual energy savings of 47.2% in the tropical city of Mexico City, demonstrating the potential to extend the driving range through thermal management optimization. This work provides a new solution for all‐season energy savings in electric vehicles, helping to promote the electric vehicle business.