Passive daytime radiative cooling: Fundamentals, material designs, and applications

Abstract Passive daytime radiative cooling (PDRC) dissipates terrestrial heat to the extremely cold outer space without using any energy input or producing pollution. It has the potential to simultaneously alleviate the two major problems of energy crisis and global warming. In this review, we summarize general strategies implemented for achieving PDRC and various applications of PDRC technologies. We first introduce heat transfer processes involved in PDRC, including radiative and nonradiative heat transfer processes, to evaluate the PDRC performance. Subsequently, we summarize the general material designs used for controlling PDRC performance, such as tuning the thermal mid‐infrared emittance and solar reflectance. Finally, we discuss the diverse applications of PDRC technologies to overcome problems in space cooling, solar cell cooling, water harvesting, and electricity generation. image