Daytime passive radiative cooling materials based on disordered media: A review

Daytime passive radiative cooling (DPRC), a cooling method without extra energy consumption, has attracted more and more attentions in recent years. The strong reflection ability in the sunlight waveband (0.3–2.5 μm) and the intensive infrared radiative characteristic within the atmospheric window (8–13 μm), which called spectral selectivity, are the key point to realize DPRC. Spectral selectivity achieved by photonic crystals are difficult to promote on large scale because of complicated manufacturing process. With the rapid development of nanotechnology, materials with disordered media are playing an increasingly important role in functional devices. Combining disordered media with polymeric photonics will become an effective way to realize the large-scale preparation of DPRC materials. This review summarizes two kinds of disordered DPRC structures, paint and film with fillers, as well as porous polymers, including the influence of types, morphology, and particle size of fillers, as well as pore morphology, pore size distribution and preparation methods of porous polymers on the spectral performance and cooling effect of radiators. Also, we briefly introduce the biologically inspired microstructures for radiative cooling, in order to provide guidance for the practical application of DPRC materials.