11:00 〜 11:15
▲ [17a-Z05-8] Transparent fluoropolymer for daytime radiative cooling
キーワード：radiative cooling, transparent fluoropolymer
Radiative cooling (RC) is a passive way to dissipate heat to the universe through the atmospheric transparent window (ATW) with no electrical power. Thus, it has attracted attention to global energy saving such as cooling buildings, vehicles, or solar cells. For the practical use of daytime RC, the RC materials must be weather-resistant, in addition to the strong absorption at the ATW (8 to 13 µm) and transparency at the visible and near-infrared regions. Here we report the RC efficiency of fluoropolymer (Lumiflon, AGC) films and compared that of various samples: polydimethylsiloxane (PDMS) and polyethylene (PE) films, a silica plate, a silica plate with silica particles (Φ20 µm), and a 100-nm thick gold film. The polymers were deposited on the gold film, which shows low RC efficiency, to reduce the RC from a substrate.
The fluoropolymer films show great RC efficiency, even at a thickness less than 50 µm. The δT was 7.6 ± 0.5 K. As for PE films, δT gradually increases with the thickness and seems to be constant at 300 µm and δT is 5.4 K. A 350 µm-thick PDMS film shows the RC efficiency of 7.7 K, as high as that of the fluoropolymer films. The silica plate with silica particles shows the RC performance higher than that of a silica plate. This is because of localized phonon-polaritions in the silica particles at around 9 µm. In conclusion, the fluoropolymer is a potential material for daytime RC, because of the following reasons: the fluoropolymer films have (a) high RC performance even with thicknesses less than 50 µm, (b) high weather-resistant property, and (c) 98% of transmission in the visible wavelength region.
The fluoropolymer films show great RC efficiency, even at a thickness less than 50 µm. The δT was 7.6 ± 0.5 K. As for PE films, δT gradually increases with the thickness and seems to be constant at 300 µm and δT is 5.4 K. A 350 µm-thick PDMS film shows the RC efficiency of 7.7 K, as high as that of the fluoropolymer films. The silica plate with silica particles shows the RC performance higher than that of a silica plate. This is because of localized phonon-polaritions in the silica particles at around 9 µm. In conclusion, the fluoropolymer is a potential material for daytime RC, because of the following reasons: the fluoropolymer films have (a) high RC performance even with thicknesses less than 50 µm, (b) high weather-resistant property, and (c) 98% of transmission in the visible wavelength region.