Scalable multifunctional radiative cooling materials

Passive daytime radiative cooling (PDRC) with zero energy consumption and pollution is regarded as one of the most feasible solutions to replace conventional electrical cooling in the energy-intensive world. Scalable multifunctional radiative cooling materials have great significance to expand the practical applications and advance the progress of this cooling technology, which would bridge the gap between fundamental research and industry. In this review, we focus on the general design strategies with scalable fabrication techniques and multifunction of PDRC materials. Firstly, fundamental principles of PDRC are briefly introduced to evaluate the cooling performance with respect to achieving both high solar reflectance and strong thermal emittance of PDRC coolers. Secondly, the scale-up design strategies of PDRC coolers with various structures and materials are highlighted. Thirdly, the advantages of scalable multifunctional PDRC coolers concerning anti-contamination, durability, energy-saving, intelligence and other characteristics are presented. Finally, diverse commercial applications of scalable PDRC materials in energy-saving building, solar cells cooling, personal thermal management, and water harvesting are discussed. The future-oriented challenges and opportunities of PDRC materials are also indicated. Therefore, this review is envisioned to not only provide fabrication methods of scalable and multi-function PDRC materials, but also put this energy-free cooling technology forward real-world applications.