Broadband Light Management with Thermochromic Hydrogel Microparticles for Smart Windows

Intelligent control of solar irradiance through windows is promising to reduce building energy consumption by at least 1.055 × 10 ¹⁵ kJ/year in the United States. Light management with thermochromic smart windows holds practical significance due to their autonomous system and simplicity of the device. However, the conventional thermochromic material (VO ₂ ) faces scientific challenges with a high phase-transition temperature (68°C) and poor thermochromic performance. Temperature-responsive hydrogel emerges as a promising alternative, whereby light management could be pursued by maneuvering the light-scattering behaviors. This work reports the strategy to explore the thermochromic performance of co-polymerized hydrogel microparticles with the aid of tailoring particle size and internal structure. The solar modulation was effectively extended into the infrared region, and an unprecedented solar transmittance modulation of 81.3% was achieved at ∼32°C by our hydrogel thermochromic device with great scalability and stability.