Spatially-Segmented Colored Radiative Cooler With Angle-Robustness

Abstract

Conventional radiative cooling devices are white or silver in color to achieve high reflectance in the solar spectral range. However, a versatile color that can be applied to the radiative cooler is required for practical application. To determine the boundary between coloration and cooling performance, the reflectance in the visible range should be fine-tuned. Here, this paper presents a spatially-segmented colored radiative cooler (SSCRC), which is a 2-dimensional micro-patterning of colored areas, with angle-robustness. By using the metal-insulator-metal (MIM) optical resonator incorporating high refractive index dielectric ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e.,</i> TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), the SSCRC shows consistent coloration in a wide-angle ranging up to 70°. In addition, the spatial segmentation introduced in the colored radiative cooler coordinates the relationship between solar absorption and vivid coloration. We perform the systematic designs in terms of spectrum, thermal analyses, and color coordinates. Finally, experimental demonstrations confirm the theoretical results on the coloration/cooling performance of SSCRC during the daytime.