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Abstract Passive radiative cooling, drawing heat energy of objects to the cold outer space through the atmospheric transparent window, is significant for reducing the energy consumption of buildings. Daytime and nighttime radiative cooling have been extensively investigated in the past. However, radiative cooling which can continuously regulate its cooling temperature, like a valve, according to human need is rarely reported. In this study, we propose a reconfigurable photonic structure, based on the effective medium theory and semi-analytical calculations, for the adaptive radiative cooling by continuous variation of the emission spectra in the atmospheric window. This is realized by the deformation of a one-dimensional polydimethylsiloxane (PDMS) grating and nanoparticle-embedded PDMS thin film when subjected to mechanical stress/strain. The proposed structure reaches different stagnation temperatures under certain strains. A dynamic tuning in emissivity under different strains results in a continuously variable “ON”/“OFF” mode in a particular atmospheric window that corresponds to the deformation-induced fluctuation of the operating temperatures of the reconfigurable nanophotonic structure.
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An Ultrathin Transparent Radiative Cooling Photonic Structure with a High NIR Reflection
Abstract With a high NIR reflection, a transparent radiative cooling photonic structure consisting of 2D silica gratings atop ZnO/Ag/ZnO is conceived and demonstrated. With 77% visible light transmitted, 57% NIR solar radiation reflected and 91% thermal infrared radiation emitted, a synthetical cooling is realized by this photonic structure. The theoretical total cooling power of this structure is more than double that of a planar silica and is 63.3% higher than that of a typical NIR reflecting filter, that is, ZnO/Ag/ZnO film. The field test facing the sunlight shows that the air temperature inside a chamber sealed with this structure is 12.5 and 2.5 °C lower than that sealed with planar silica and ZnO/Ag/ZnO, respectively. This work shows that the concept of daytime radiative cooling can be applied in combination with the utilization of visible light and the proposed ultrathin photonic structure shows potentials for passive radiative cooling of transparent applications.
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- Award ID(s):
- 2011401
- PAR ID:
- 10377083
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 9
- Issue:
- 30
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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