Abstract Nanoporous self-ordered anodic aluminum oxide (AAO) film has shown great promise for applications in passive radiative heat dissipation due to its high infrared thermal emissivity and its good economic efficiency for mass production. However, the passive radiative cooling mechanism of AAO is not yet fully understood. In this study, the finite-difference time-domain (FDTD) method is adopted to theoretically investigate how the structure of AAO, pore diameter, interpore distance, porosity, and thickness included, impact its infrared spectral emissivity for radiative cooling. The results demonstrate that the infrared spectral emissivity of AAO film is mainly influenced by the porosity and the film thickness. There exists an optimal porosity for a certain film thickness to obtain the maximum infrared emissivity. When the difficulty in practical fabrication of thick AAO film is considered, the ideal AAO film thickness locates between 50 and 100 μm. The results reported in this study can be exploited to guide the design and development of high-emissivity passive radiative cooling materials.

中文翻译：

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研究用于被动辐射散热的自有序阳极氧化铝的红外光谱辐射特性a,b

摘要 纳米多孔自有序阳极氧化铝（AAO）薄膜由于其高红外热发射率和良好的批量生产经济效益，在被动辐射散热方面显示出广阔的应用前景。然而，AAO的被动辐射冷却机制尚未完全了解。在本研究中，采用有限差分时域（FDTD）方法从理论上研究了 AAO 的结构、孔径、孔间距、孔隙率和厚度如何影响其辐射冷却的红外光谱发射率。结果表明，AAO薄膜的红外光谱发射率主要受孔隙率和薄膜厚度的影响。一定膜厚下存在最佳孔隙率以获得最大红外发射率。考虑到实际制备厚 AAO 薄膜的难度，理想的 AAO 薄膜厚度在 50 到 100 μm 之间。本研究报告的结果可用于指导高发射率被动辐射冷却材料的设计和开发。