Shao Hua, Niu Junru, Zhang Yiyun, Wang Haiteng, Lu Chengtao, Ma Yaoguang, Chen Hongsheng, Li Shilong, Qian Haoliang
Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China.
ZJU-Hangzhou Global Science and Technology Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China.
ACS Appl Mater Interfaces. 2024 Oct 23;16(42):57246-57252. doi: 10.1021/acsami.4c14473. Epub 2024 Oct 10.
Passive cooling is regarded as the desired method for interior temperature regulation due to its advantage of energy consumption reduction. An ideal passive-cooling window is expected to exhibit a high emissivity in the mid-infrared (MIR, 8-13 μm) spectral range for cooling and a low transmittance in the near-infrared (NIR, 780-2100 nm) spectral range for reducing heat flow, while presenting a high transmittance in the visible (VIS, 400-780 nm) spectral range for daylighting. However, material structures that meet these requirements often come with high demands for precision in manufacturing and elevated processing costs, which have limited their potential for large-scale mass production. Here, we propose a mass-producible transparent flexible passive-cooling film that is relatively easy to process and low-cost and meets all of the requirements mentioned above. The film is made of poly(methyl methacrylate) mixed with CsWO nanoparticles, and it shows a high absorptance (80%) in NIR for blocking solar radiation penetration and a high emissivity (93%) in MIR for radiative cooling as well as a reasonable transmittance (40%) in VIS for visibility. Under solar intensity of ∼900 W/m, a maximum temperature reduction of 8.4 and 7.8 °C has been achieved for a window coated by the film compared to the uncoated window in the condition of the absorbing chamber and car, respectively. Such a mass-producible transparent flexible passive-cooling film holds promising applications in large windows, such as those used in automobiles and buildings, where there is a high demand for both daylighting and cooling.
被动冷却因其具有降低能耗的优势，被视为室内温度调节的理想方法。理想的被动冷却窗预计在中红外（MIR，8 - 13μm）光谱范围内具有高发射率以实现冷却，在近红外（NIR，780 - 2100nm）光谱范围内具有低透过率以减少热流，同时在可见光（VIS，400 - 780nm）光谱范围内具有高透过率以实现采光。然而，满足这些要求的材料结构通常对制造精度有很高要求，且加工成本高昂，这限制了它们大规模量产的潜力。在此，我们提出一种可大规模生产的透明柔性被动冷却薄膜，其加工相对容易且成本低廉，满足上述所有要求。该薄膜由聚甲基丙烯酸甲酯与CsWO纳米颗粒混合制成，在近红外波段显示出高吸收率（80%）以阻挡太阳辐射穿透，在中红外波段具有高发射率（93%）以进行辐射冷却，在可见光波段具有合理的透过率（40%）以保证可见度。在约900W/m的太阳强度下，与未镀膜的窗户相比，在吸收腔和汽车环境中，用该薄膜镀膜的窗户分别实现了最大8.4℃和7.8℃的降温。这种可大规模生产的透明柔性被动冷却薄膜在大型窗户（如汽车和建筑中使用的窗户）中具有广阔的应用前景，这些窗户对采光和冷却都有很高的要求。
