Fundamentals, Materials, and Applications for Daytime Radiative Cooling

Abstract Daytime radiative cooling is emerging as a passive and environmentally friendly cooling strategy, compared to traditional cooling methods that consume a vast amount of energy with a significant carbon footprint. To achieve the best cooling performance, materials tailored for daytime radiative cooling need to generate high emission in the atmospheric transmission window (8–13 µm) for radiating heat out directly to the universe and simultaneously reflect the entire solar radiation to minimize the thermal load. Recently, daytime subambient radiative cooling has been demonstrated through a range of novel material strategies. Herein, the fundamental principles for nighttime and daytime radiative cooling are summarized, and different designs of materials and structures suitable for substantial cooling performances are highlighted, together with various real‐world applications including building, water cooling, and clothing. Several possible pathways of daytime radiative cooling for further development are also outlined. It is anticipated that this review will provide an overall picture of recent progress and inspire more efforts into the fundamental understanding and practical applications of daytime radiative cooling.