Microscopic mechanism and applications of radiative cooling materials: A comprehensive review

This paper presents a state-of-the-art review on the microscopic mechanisms of existing radiative cooling materials. In this review, we analyze the microscopic mechanisms of efficient mid-infrared emissivity generated by photonic crystal-based radiative coolers, polymer-based radiative coolers, polar dielectric particle-polymer-based radiative coolers, and adaptive radiative coolers after clarifying the basic physical concepts of radiative cooling. Then, the mid-infrared emissivity and associated cooling properties of different materials, advantages and disadvantages of different radiative coolers and their application scenarios are discussed in detail. Finally, the threshold of spectral modulation is derived to address the relationship between mid-infrared emissivity and solar reflectance to achieve radiative cooling. This review can provide guidance for the design and application of radiative coolers.