Pillar-Pore-Structured Nanophotonic Coating with Superior Solar and Thermal Modulation Abilities

Abstract There is a growing focus on the development of advanced materials to enhance energy efficiency in space heating and cooling, which accounts for 13% of the annual consumption of global energy. Wavelength-selective dynamic regulation is undisputedly requisite to solve this problem. Radiative cooling materials work in the wavelength span of 8-14 µm, which is effective in heat dissipation. However, their fixed emissivity results in unpleasant undercooling. Adaptive cooling materials can change emissivity in response to temperature shifts, solving the problem of overcooling, however they absorb too much solar heat in daytime, especially in summer. Hence, a material is requisite to have high reflectance in solar wavelengths (0.25 – 2.5 µm). To address this issue, we propose a temperature-adaptive radiative cooling coating with high solar reflectance that efficiently reflects solar radiation and automatically switches its sky-window emissivity from 0.19 to 0.74, delivering an 85.92% solar reflectance for optimal energy efficiency and all-year-round thermal comfort within a specific climate zone. The simulations demonstrate that our sample surpasses existing roofing coatings in terms of energy efficiency across different climate zones, particularly those with substantial seasonal variations.