Efficient thermal management and all-season energy harvesting using adaptive radiative cooling and a thermoelectric power generator

Passive daytime radiative cooling (PDRC) is useful for thermal management because it allows an object to emit terrestrial heat into space without the use of additional energy. To produce sub-ambient temperatures under direct sunlight, PDRC materials are designed to reduce their absorption of solar energy and to enhance their long-wavelength infrared (LWIR) emissivity. In recent years, many photonic structures and polymer composites have been studied to improve the cooling system of buildings. However, in cold weather (i.e., during winter in cold climates), buildings need to be kept warm rather than cooled due to heat loss. To overcome this limitation, temperature-responsive radiative cooling is a promising alternative. In the present study, adaptive radiative cooling (ARC) film fabricated from a polydimethylsiloxane/hollow SiO2 microsphere/thermochromic pigment composite was investigated. We found that the ARC film absorbed solar radiation under cold conditions while exhibiting radiative cooling at ambient temperatures above 40 °C. Thus, in outdoor experiments, the ARC film achieved sub-ambient temperatures and had a theoretical cooling power of 63.2 W/m2 in hot weather. We also demonstrated that radiative cooling with an energy harvesting system could be used to improve the energy management of buildings, with the thermoelectric module continuously generating output power using the ARC film. Therefore, we believe that our proposed ARC film can be employed for efficient thermal management of buildings and all-season energy harvesting in the near future.