Materials, structures, and devices for dynamic radiative cooling

Radiative cooling is the process by which an object on the Earth's surface loses heat by emitting thermal radiation into space through the atmospheric window. Because thermal radiation is continuous in time, radiative cooling may cause overcooling in winter or at night. Therefore, it is essential to develop dynamic radiative cooling (DRC) approaches as opposed to "static" radiative cooling. In this work, we classify DRC into passive and active approaches according to different sources of external response. By reviewing the dual-band co-modulation mechanisms and application fields of approaches with DRC potential, we provide a comprehensive analysis of the principles, structures, optical modulation, thermal performance, and energy-saving potentials of different DRC modulation mechanisms. It should be noted that combining high-performance and low-cost radiative cooling/solar absorbing materials with active mechanical modulation devices is the most readily available and promising approach for DRC applications. Furthermore, improvements in low-cost manufacturing are usually overlooked compared with the optimization of optical properties.