Yang Lili, Wang Gang, Duan Shuxian, Zhang Jinrui, Li Chong
School of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
Key Laboratory of Thermal Management and Energy Utilization of Aviation Vehicles, Ministry of Industry and Information Technology, Nanjing, Jiangsu 210016, China.
ACS Appl Mater Interfaces. 2024 Nov 13;16(45):62827-62837. doi: 10.1021/acsami.4c10050. Epub 2024 Nov 1.
Daytime radiative cooling offers a novel solution to the energy crisis, enabling green and efficient thermal management in space. High reflectance in the solar spectrum is essential for passive radiative cooling, rendering dye coloring and similar methods unsuitable for colored coolers. This paper presents a structurally colored photonic crystal biomimetic microstructured radiative cooler. Inspired by natural biological systems, this cooler features a dual-layered microtruncated-cone array structure on the surface and bottom membrane layers. The silver reflector and 3D micrograting surface structure produce continuous iridescent colors through multiple interference effects. Optimized lithographic process enable the fabrication of the ordered dual-layer surface microstructure arrays with precise angular combinations. The dual-layered microtruncated-cone introduces a gradient refractive index, reducing impedance mismatch at the interface. As a result, the radiative cooler achieves high solar spectral reflectance (0.95) and high mid-infrared emissivity (0.95). Notably, the net theoretical cooling power and the subambient temperature drop are 106.9 W m and 7.4 °C, respectively, at an ambient temperature of 40 °C, with a measured average temperature reduction of 6.1 °C under direct sunlight. This performance matches that of advanced radiative coolers, striking a balance between aesthetics and radiative cooling capability.
日间辐射冷却为能源危机提供了一种新颖的解决方案，能够在太空实现绿色高效的热管理。太阳光谱中的高反射率对于被动辐射冷却是必不可少的，这使得染料着色和类似方法不适用于有色冷却器。本文提出了一种结构色光子晶体仿生微结构辐射冷却器。受自然生物系统的启发，该冷却器在表面和底部膜层具有双层微截顶圆锥阵列结构。银反射器和三维微光栅表面结构通过多重干涉效应产生连续的彩虹色。优化的光刻工艺能够制造出具有精确角度组合的有序双层表面微结构阵列。双层微截顶圆锥引入了梯度折射率，减少了界面处的阻抗失配。结果，辐射冷却器实现了高太阳光谱反射率（0.95）和高中红外发射率（0.95）。值得注意的是，在环境温度为40℃时，净理论冷却功率和低于环境温度的降幅分别为106.9 W/m和7.4℃，在直射阳光下测量的平均温度降低了6.1℃。这种性能与先进的辐射冷却器相当，在美观性和辐射冷却能力之间取得了平衡。
