Tunable Coatings on Various Substrates for Self-Adaptive Energy Harvesting with Daytime Solar Heating and Nighttime Radiative Cooling
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arXiv
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| Formato: | Preprint |
| Publicado: |
2025
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| author | Araki, Ken Rajan, Vishwa Krishna Wang, Liping |
| author_facet | Araki, Ken Rajan, Vishwa Krishna Wang, Liping |
| contents | In this work, tunable vanadium dioxide (VO2) metafilms on different substrate materials fabricated via low-oxygen furnace oxidation are demonstrated for self-adaptive daytime solar heating and nighttime radiative cooling. Because of its thermally-driven insulator-to-metal phase transition behavior, the VO2 metafilms work as spectrally-selective solar absorber with a high solar absorptance of 0.86 and a low infrared emissivity of ~0.2 at daytime, while they behave as selective cooler at nighttime to dissipate heat effectively through the atmospheric transparency window with a high emissivity of ~0.76 to cold outer space. From the outdoor vacuum tests, a significant temperature rise up to 169 K upon solar heating and a temperature drop of 17 K at night are experimentally observed from these tunable VO2 metafilms. With the atmosphere temperature fitted in-situ, the accurate heat transfer model shows excellent agreement with the stagnation temperature measurement, and indicates a high heating power of ~400 W/m2 at 80°C sample temperature in the middle of the day, and a cooling power of ~60 W/m2 at 30°C in equilibrium with ambient at night. This work would facilitate the development of self-adaptive coatings with cost-effective and scalable fabrication approaches for all-day energy harvesting. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_02921 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Tunable Coatings on Various Substrates for Self-Adaptive Energy Harvesting with Daytime Solar Heating and Nighttime Radiative Cooling Araki, Ken Rajan, Vishwa Krishna Wang, Liping Materials Science Optics In this work, tunable vanadium dioxide (VO2) metafilms on different substrate materials fabricated via low-oxygen furnace oxidation are demonstrated for self-adaptive daytime solar heating and nighttime radiative cooling. Because of its thermally-driven insulator-to-metal phase transition behavior, the VO2 metafilms work as spectrally-selective solar absorber with a high solar absorptance of 0.86 and a low infrared emissivity of ~0.2 at daytime, while they behave as selective cooler at nighttime to dissipate heat effectively through the atmospheric transparency window with a high emissivity of ~0.76 to cold outer space. From the outdoor vacuum tests, a significant temperature rise up to 169 K upon solar heating and a temperature drop of 17 K at night are experimentally observed from these tunable VO2 metafilms. With the atmosphere temperature fitted in-situ, the accurate heat transfer model shows excellent agreement with the stagnation temperature measurement, and indicates a high heating power of ~400 W/m2 at 80°C sample temperature in the middle of the day, and a cooling power of ~60 W/m2 at 30°C in equilibrium with ambient at night. This work would facilitate the development of self-adaptive coatings with cost-effective and scalable fabrication approaches for all-day energy harvesting. |
| title | Tunable Coatings on Various Substrates for Self-Adaptive Energy Harvesting with Daytime Solar Heating and Nighttime Radiative Cooling |
| topic | Materials Science Optics |
| url | https://arxiv.org/abs/2509.02921 |