Highly Efficient and Versatile Daytime Radiative Cooler Based on Optimized Polymer-Ceramic Composite Fabricated via Facile Process

Radiative cooling is a carbon-free, zero energy technology that can substitute various energy-consuming cooling systems such as air conditioners and auto-chillers for cooling heat-generating machines. Previous reports on radiative cooling have focused mainly on the cooling performance, thereby overlooking the applicability, structural complexity, manufacturing complexity, and certain physical properties of the cooler. In this study, we present an efficient, applicable, and facile-fabricated radiative cooler composed of poly(vinylidene fluoride-co-hexafluoro propene) (P(VDF-HFP)) and alumina (Al₂O₃). Apart from being fabricated in the form of a freestanding sheet with 97.5% solar reflectance and 94.8% infrared (IR) emissivity, the P(VDF-HFP)/Al₂O₃-based radiative cooler (PARC) can be applied to solid substrates via simple coating techniques. This shows that the PARC can be introduced in architecture, clothing, and other fields that demand cooling. The PARC‘s cooling performance is experimentally proven by a sub-ambient temperature drop of 5.8 °C and the cooling power of the PARC is calculated to be 125.6 Wm^-2 under the AM1.5 global spectrum, which is superior to that of previously reported radiative cooling emitters.