All-Inorganic HIP Multilayer With Excellent Thermostability For High-Performance Dual-Selective Radiative Cooling

All-Inorganic HIP Multilayer With Excellent Thermostability For High-Performance Dual-Selective Radiative Cooling | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Physical Sciences - Article All-Inorganic HIP Multilayer With Excellent Thermostability For High-Performance Dual-Selective Radiative Cooling Cong Wang, Atsha Ambar, Huan Liu, Yingxin Yang, Ying Sun This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6701263/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Passive daytime radiative cooling (PDRC) enables sustainable, energy-free thermal management by reflecting sunlight and emitting heat through Earth's atmospheric window (8–13 µm) into outer space. However, this potential remains unrealized, as organic coolers degrade rapidly under sunlight, while inorganic ones face high cost, structural intricacy, suboptimal emissivity, and struggle to balance high solar reflectivity. Most also underutilize the broader mid-infrared (8–20 µm) spectrum, restricting space applications where no atmosphere aids cooling. To address these challenges, we propose a simple, low-cost, all-inorganic dual-selective multilayer structure comprising SiO 2 capping alternating Si 3 N 4 /Al 2 O 3 high-index pair (HIP) atop an AlN-protected Ag reflector via magnetron sputtering over quartz substrate. The SiO 2 /HIP interface induces strong impedance mismatch through low/high refractive index contrast, enhancing atmospheric emissivity, while the HIP structure broadens mid-IR emission. The AlN barrier prevents Ag oxidation while sustaining emissivity. Optical analysis of the MATLAB-optimized structure reveals 96.04% solar reflectivity, 91.06% atmospheric emissivity, and a 19.8 K sub-ambient temperature drop, yielding ~225 W·m -2 net cooling power—the highest value reported for inorganic multilayers. Notably, full mid-IR emissivity reaches 90.03%, surpassing conventional inorganic radiative coolers. SEM images confirm distinct, well-aligned columnar layers, validating deposition fidelity. The thermal inertness by TG-DSC analyses confirms 0.01% mass loss at 1450°C, confirming film's stability and suitability for extreme environments. Outdoor test confirms real-world efficacy, achieving up to 5.2°C sub-ambient temperature reduction under 960 W·m -2 solar irradiance despite cloud cover and wind. This scalable design addresses material scarcity, structural complexity, and spectral trade-offs, paving the way for terrestrial and extraterrestrial PDRC applications. Physical sciences/Nanoscience and technology/Nanoscale materials/Organic–inorganic nanostructures Earth and environmental sciences/Environmental sciences/Environmental impact Earth and environmental sciences/Climate sciences/Climate change/Climate-change mitigation Physical sciences/Energy science and technology/Energy modelling radiative cooling inorganic multilayer film infrared emissivity solar reflectivity atmospheric window high-index pair (HIP) thermal management Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryAl2O3Si3N4.pdf All-Inorganic HIP Multilayer With Excellent Thermostability For High-Performance Dual-Selective Radiative Cooling Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6701263","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":461968386,"identity":"708e9e9b-d6d7-4385-b19e-a210a0ef0932","order_by":0,"name":"Cong 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high-index pair (HIP), thermal management","lastPublishedDoi":"10.21203/rs.3.rs-6701263/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6701263/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Passive daytime radiative cooling (PDRC) enables sustainable, energy-free thermal management by reflecting sunlight and emitting heat through Earth's atmospheric window (8–13 µm) into outer space. However, this potential remains unrealized, as organic coolers degrade rapidly under sunlight, while inorganic ones face high cost, structural intricacy, suboptimal emissivity, and struggle to balance high solar reflectivity. Most also underutilize the broader mid-infrared (8–20 µm) spectrum, restricting space applications where no atmosphere aids cooling. To address these challenges, we propose a simple, low-cost, all-inorganic dual-selective multilayer structure comprising SiO\u003csub\u003e2\u003c/sub\u003e capping alternating Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e high-index pair (HIP) atop an AlN-protected Ag reflector via magnetron sputtering over quartz substrate. The SiO\u003csub\u003e2\u003c/sub\u003e/HIP interface induces strong impedance mismatch through low/high refractive index contrast, enhancing atmospheric emissivity, while the HIP structure broadens mid-IR emission. The AlN barrier prevents Ag oxidation while sustaining emissivity. Optical analysis of the MATLAB-optimized structure reveals 96.04% solar reflectivity, 91.06% atmospheric emissivity, and a 19.8 K sub-ambient temperature drop, yielding ~225 W·m\u003csup\u003e-2\u003c/sup\u003e net cooling power—the highest value reported for inorganic multilayers. Notably, full mid-IR emissivity reaches 90.03%, surpassing conventional inorganic radiative coolers. SEM images confirm distinct, well-aligned columnar layers, validating deposition fidelity. The thermal inertness by TG-DSC analyses confirms 0.01% mass loss at 1450°C, confirming film's stability and suitability for extreme environments. Outdoor test confirms real-world efficacy, achieving up to 5.2°C sub-ambient temperature reduction under 960 W·m\u003csup\u003e-2\u003c/sup\u003e solar irradiance despite cloud cover and wind. This scalable design addresses material scarcity, structural complexity, and spectral trade-offs, paving the way for terrestrial and extraterrestrial PDRC applications.","manuscriptTitle":"All-Inorganic HIP Multilayer With Excellent Thermostability For High-Performance Dual-Selective Radiative Cooling","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-28 03:19:43","doi":"10.21203/rs.3.rs-6701263/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c72f671f-4e34-4d3b-8115-2ca89f7c6641","owner":[],"postedDate":"May 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":49054608,"name":"Physical sciences/Nanoscience and technology/Nanoscale materials/Organic\u0026#x2013;inorganic nanostructures"},{"id":49054609,"name":"Earth and environmental sciences/Environmental sciences/Environmental impact"},{"id":49054610,"name":"Earth and environmental sciences/Climate sciences/Climate change/Climate-change mitigation"},{"id":49054611,"name":"Physical sciences/Energy science and technology/Energy modelling"}],"tags":[],"updatedAt":"2025-11-21T07:07:09+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-28 03:19:43","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6701263","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6701263","identity":"rs-6701263","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}