Progress in passive daytime radiative cooling from spectral design to real application

High-performance cooling technology is increasingly critical due to the rising frequency of extremely hot weather caused by global warming. Passive daytime radiative cooling (PDRC) is an emerging zero-energy-consumption technology that provides sub-ambient cooling under strong solar conditions by emitting heat to the cold outer space (~ 3 K) while minimizing heat gain from solar irradiation. This technology has attracted wide attention and achieved huge progress in the past decade. Recently, extensive efforts have been devoted to constructing high-performance PDRC materials in various fields, such as thermal management of buildings, human comfort, equipment, and dynamic devices. However, there is still a big gap between the laboratory-reported PDRC materials and their practical applications because of their high costs, complex manufacturing processes, insufficient cooling performance, and potential nano- or micro-hazards. In this review, we summarized recent advancements in PDRC technology and focused on the spectral design, cooling mechanisms, and practical applications of PDRC materials. We also discussed the challenges and strategies for bridging the gap between academic research and real-world implementation. We hope that this review will provide more insight into the further development of advanced PDRC technologies.