Chen Yijun, Mandal Jyotirmoy, Li Wenxi, Smith-Washington Ajani, Tsai Cheng-Chia, Huang Wenlong, Shrestha Sajan, Yu Nanfang, Han Ray P S, Cao Anyuan, Yang Yuan
Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA.
Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China.
Sci Adv. 2020 Apr 24;6(17):eaaz5413. doi: 10.1126/sciadv.aaz5413. eCollection 2020 Apr.
Solar reflective and thermally emissive surfaces offer a sustainable way to cool objects under sunlight. However, white or silvery reflectance of these surfaces does not satisfy the need for color. Here, we present a paintable bilayer coating that simultaneously achieves color and radiative cooling. The bilayer comprises a thin, visible-absorptive layer atop a nonabsorptive, solar-scattering underlayer. The top layer absorbs appropriate visible wavelengths to show specific colors, while the underlayer maximizes the reflection of near-to-short wavelength infrared (NSWIR) light to reduce solar heating. Consequently, the bilayer attains higher NSWIR reflectance (by 0.1 to 0.51) compared with commercial paint monolayers of the same color and stays cooler by as much as 3.0° to 15.6°C under strong sunlight. High NSWIR reflectance of 0.89 is realized in the blue bilayer. The performances show that the bilayer paint design can achieve both color and efficient radiative cooling in a simple, inexpensive, and scalable manner.
太阳能反射和热发射表面提供了一种在阳光下冷却物体的可持续方法。然而，这些表面的白色或银色反射率无法满足对颜色的需求。在此，我们展示了一种可涂覆的双层涂层，它能同时实现颜色和辐射冷却。该双层由一层薄的可见光吸收层和一层非吸收性的太阳散射底层组成。顶层吸收适当的可见波长以呈现特定颜色，而底层则使近至短波长红外（NSWIR）光的反射最大化，以减少太阳加热。因此，与相同颜色的商业单层涂料相比，该双层涂层的NSWIR反射率更高（提高了0.1至0.51），并且在强烈阳光下温度可降低多达3.0°C至15.6°C。蓝色双层涂层实现了0.89的高NSWIR反射率。这些性能表明，双层涂料设计能够以简单、廉价且可扩展的方式同时实现颜色和高效辐射冷却。
