Near Infrared-Blocking Thermochromic Hydrogel Smart Windows for Passive Solar Heat Control
Yaoyao Zhou1,2, Jiake Wang1, Sunmiao Fang1
1Sustainable Photonics Energy Research Laboratory, Material Science Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal23955-6900, Saudi Arabia.
Abstract:
Excessive solar heat gain through transparent enclosures is a critical challenge for buildings, vehicles, and greenhouse agriculture, particularly in hot-arid regions where indoor overheating increases the demand for energy- and water-intensive cooling. Herein, we report an interpenetrating-network thermoresponsive hydrogel smart window that passively regulates greenhouse heat gain through thermochromic solar modulation and nanomaterial-enabled near-infrared attenuation. The incorporation of Cs0.33WO3 nanoparticles into the hydrogel endows it with strong near-infrared (NIR) absorption, blocking 89.6% of incident NIR radiation and promoting rapid thermochromic switching under solar illumination. As a result, the hydrogel window delivers high solar transmittance modulation capability (37.5%) while maintaining large luminous transmittance (74.3%), allowing sufficient transmission of visible light for plant photosynthesis. Additionally, a gel-air bilayer architecture is designed to enhance thermal insulation under hot-arid conditions. Greenhouse cultivation in Saudi Arabia is employed as a practical testbed to evaluate the effectiveness of the proposed solar management strategy. The proposed hydrogel smart window reduces soil temperature in a greenhouse by up to 12 °C and improves crop yield by 66.7% compared with conventional plastic panels. Overall, this work establishes a passive, climate-adaptive smart-window strategy for thermal management in greenhouses and sustainable crop production in extreme environments.
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