Recent Advances in Material Engineering and Applications for Passive Daytime Radiative Cooling

Passive daytime radiative cooling (PDRC) is a game-changing strategy for cooling, aiming to alleviate the major problems such as global warming. It is featured with zero energy consumption and zero environmental pollution, bringing about revolutionary change compared with conventional cooling systems. The key challenge in the exciting arena of PDRC research lies in the material design and engineering, aiming to meet the requirement for the optical characteristics on the two very different ranges of wavelength. To possess the optimal cooling performance, materials constructed for daytime radiative cooling are required to show extremely low absorptivity for wavelengths of solar irradiation (0.3-2.5 mu m) to minimize the thermal load, while having high emissivity within the atmospheric transmission window (8-13 mu m) for emitting heat out directly to the outer space. The current review takes a specific perspective of material science and engineering to summarize the most recent advances in PDRC. The fundamental principles for daytime radiative cooling and material design are summarized, and recent works on PDRC material engineering and correlated applications are highlighted. Technical details and prospects for each type of PDRC materials are discussed. The future challenges and opportunities of PDRC materials are also proposed.