Passive radiative cooling using temperature-dependent emissivity can sometimes outperform static emitters
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866916792532729856 |
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| author | Jin, Yeonghoon Cho, Jin-Woo Kats, Mikhail A. |
| author_facet | Jin, Yeonghoon Cho, Jin-Woo Kats, Mikhail A. |
| contents | In passive sky-facing radiative cooling, wavelength-selective thermal emitters in the atmospheric transparency window of 8-13 $μ$m can reach lower temperatures compared to broadband emitters, but broadband emitters always have higher cooling power when the emitter is warmer than the ambient. Here, we propose a temperature-tunable thermal emitter that switches between a wavelength-selective state -- with high emissivity only in the atmospheric transparency window of 8-13 $μ$m -- and a broadband-emissive state with high emissivity in the 3-25 $μ$m range, thus maintaining high cooling potential across all temperatures. We also propose a realization of such a temperature-tunable emitter using the phase transition of vanadium dioxide (VO$_2$), which can be tuned to the ambient temperature using a combination of doping and defect engineering. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_11259 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Passive radiative cooling using temperature-dependent emissivity can sometimes outperform static emitters Jin, Yeonghoon Cho, Jin-Woo Kats, Mikhail A. Optics Materials Science Applied Physics In passive sky-facing radiative cooling, wavelength-selective thermal emitters in the atmospheric transparency window of 8-13 $μ$m can reach lower temperatures compared to broadband emitters, but broadband emitters always have higher cooling power when the emitter is warmer than the ambient. Here, we propose a temperature-tunable thermal emitter that switches between a wavelength-selective state -- with high emissivity only in the atmospheric transparency window of 8-13 $μ$m -- and a broadband-emissive state with high emissivity in the 3-25 $μ$m range, thus maintaining high cooling potential across all temperatures. We also propose a realization of such a temperature-tunable emitter using the phase transition of vanadium dioxide (VO$_2$), which can be tuned to the ambient temperature using a combination of doping and defect engineering. |
| title | Passive radiative cooling using temperature-dependent emissivity can sometimes outperform static emitters |
| topic | Optics Materials Science Applied Physics |
| url | https://arxiv.org/abs/2506.11259 |