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Micro-structured polyethylene film as an optically selective and self-cleaning layer for enhancing durability of radiative coolers
Nanophotonics ( IF 7.5 ) Pub Date : 2023-05-05 , DOI: 10.1515/nanoph-2023-0198
Yi Jiang, Jiahao Wang, Yaya Zhou, Jinlei Li, Zipeng Chen, Pengcheng Yao, Haixiong Ge, Bin Zhu

Passive daytime radiative cooling (PDRC) as a zero-energy cooling technology that reflects most of sunlight and emits infrared thermal radiation to outer space, has attracted much attention. However, most PDRC materials suffer dust accumulation problem during long-term use, seriously detrimental to their cooling performance. Here, we demonstrate a micro-structured polyethylene film fabricated through a scalable hot embossing lithography (named HELPE), enables good superhydrophobic property and therefore excellent self-cleaning performance as a universal protective layer for most PDRC materials. Specifically, the precisely designed three-dimensional periodic micron columns on polyethylene film allow for high water droplet contact angle of 151°, and the intrinsic molecular bindings of polyethylene endow low solar absorption (A = 3.3 %) and high mid-infrared transmission (T = 82.3 %) for negligible optical impacts on underlying PDRC materials. Taking polyvinylidene fluoride (PVDF) radiative cooler as an example, when covered with the HELPE film the net cooling performance maintains unchanged (7.5 °C in daytime and 4.5 °C in nighttime) compared to that without HELPE film. After 12 days continuous outdoor experiment, none of obvious dust accumulation can be observed on the radiative cooler covered with HELPE film. Our work offers a universal pathway for most PDRC materials toward practical applications with minimal maintenance need.

中文翻译:

微结构聚乙烯薄膜作为光学选择和自清洁层以增强辐射冷却器的耐用性

被动日间辐射冷却(PDRC)作为一种零能耗冷却技术,反射大部分太阳光并向外层空间发射红外热辐射,备受关注。然而,大多数PDRC材料在长期使用过程中都会出现积尘问题,严重影响其散热性能。在这里,我们展示了一种通过可扩展的热压印光刻技术(名为 HELPE)制造的微结构聚乙烯薄膜,具有良好的超疏水性能,因此作为大多数 PDRC 材料的通用保护层具有出色的自清洁性能。具体来说,聚乙烯薄膜上精确设计的三维周期性微米柱允许 151° 的高水滴接触角,聚乙烯的固有分子键合赋予低太阳能吸收(A= 3.3 %) 和高中红外传输 (= 82.3 %,因为对底层 PDRC 材料的光学影响可以忽略不计。以聚偏二氟乙烯(PVDF)辐射冷却器为例,覆盖HELPE薄膜后,与未覆盖HELPE薄膜相比,净冷却性能保持不变(白天7.5°C,夜间4.5°C)。经过连续12天的户外实验,贴有HELPE膜的辐射冷却器没有明显的积尘现象。我们的工作为大多数 PDRC 材料提供了一条通向实际应用且维护需求最少的通用途径。
更新日期:2023-05-05
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