Multilayer passive radiative selective cooling coating based on Al/SiO2/SiNx/SiO2/TiO2/SiO2 prepared by dc magnetron sputtering

THIN SOLID FILMS

卷:694

Article

Cunha, N. F.¹  AL-Rjoub, A.¹  Rebouta, L.¹  Vieira, L. G.²  Lanceros-Mendez, S.^2,3,4 

[1] Univ Minho, Ctr Phys, Campus Azurem, P-4800058 Guimaraes, Portugal

[2] Univ Minho, Ctr Phys, Campus Gualtar, P-4710057 Braga, Portugal

[3] Univ Basque Country, Basque Ctr Mat Applicat & Nanostruct, BCMat, Sci Pk, Leioa 48940, Spain

[4] Ikerbasque, Basque Fdn Sci, Bilbao 48013, Spain

关键词: Passive cooling;    Optical constants;    Selective coating;   

DOI  :  10.1016/j.tsf.2019.137736

来源: Elsevier

【 摘 要 】

A multilayer passive radiative selective cooling coating based on Al/SiO2/SiNx/SiO2/TiO2/SiO2 prepared by dc magnetron sputtering is presented. The design was first theoretically optimized using the optical constants, refractive index and extinction coefficient, of thin single layers. The spectral optical constants in the wavelength range from 0.3 to 27 mu m were calculated from the transmittance and reflectance data of thin single layers deposited on silicon and glass substrates. The samples were characterized by Scanning Electron Microscopy, X-ray diffraction, Fourier-transform Infrared Spectroscopy and UV-VIS-NIR spectroscopy. It is shown that the TiO2 layer presents a partially ruffle phase polycrystalline structure and a higher refractive index than amorphous SiO2 and SiNx layers in the spectral range from 0.3 to 2.5 mu m. The cooling device was deposited on copper substrates and a thin low-density polyethylene foil with high transmittance in the 8 to 13 mu m spectral range was used as convection cover material. The device is characterized by both low reflectance (high emittance) in the sky atmospheric window (wavelength range from 8 to 13 mu m) and high hemispherical reflectance elsewhere, allowing for temperature drops of average 7.4 degrees C at night-time in winter, which corresponds to a net cooling power of similar to 43 W m(-2). Further, a temperature drop of 2.5 degrees C was obtained during winter daytime.

【 授权许可】

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