Application and research progress of transparent radiative cooling materials – a review

Abstract

Transparent radiative cooling materials possess spectrally selective optical characteristics: they exhibit excellent transmissive performance in the visible spectrum range to allow visible light to pass through while demonstrating high emissivity in the atmospheric window. As an inherent property of materials, emissivity is defined as the ratio of radiant power per unit area of a material to that of a blackbody (an ideal radiator) at the same temperature under thermal equilibrium, and it is closely related to thermal radiation. According to Kirchhoff's law, emissivity equals absorptivity under thermal equilibrium conditions. Based on the above characteristics, such materials provide crucial support for sustainable cooling technologies and show broad prospects in the field of green and low-carbon cooling. This paper systematically reviews the principles, material systems, and design strategies of such coolers, focusing on their recent advancements. We comprehensively discuss material selection (hydrogels and thin films), structural design (inorganic materials, photonic crystal multilayers, and metamaterial architectures), performance optimization strategies (enhancing infrared emissivity in the atmospheric window), and their applications in smart windows, energy-efficient buildings, and electronics cooling. Future research should address scalability and durability through cross-scale designs and bio-inspired functionalities, further advancing this field. Ultimately, transparent radiative cooling offers an eco-friendly and energy-efficient solution to meet growing global cooling demands.