Porous polymer bilayer with near-ideal solar reflectance and longwave infrared emittance

Yung Chak Anson Tsang, Nithin Jo Varghese, Mathis Degeorges, Jyotirmoy Mandal

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


This study explores the optical design of a daytime radiative cooler with near-ideal solar reflectance and longwave infrared (LWIR) emittance through materials selection and nanostructuring. Focusing on polymers as a materials platform, we introduce a bilayer architecture, comprising a porous poly(vinylidene fluoride-co-hexafluoropropene) (P(VdF-HFP)) topcoat that serves as a low-index LWIR emissive effective medium, over a nanofibrous, solar scattering polytetrafluoroethene underlayer. This novel configuration yields a superwhite coating with a near-ideal solar reflectance of >0.99, and a blackbody-like near-normal and hemispherical LWIR emittances of ∼0.98 and ∼0.96 respectively. Under humid and partially cloudy sky conditions unfavorable for radiative heat loss, these values enable the bilayer radiative cooler to achieve a subambient of 2.3 C. Given that the porous polymer bilayer uses scalable fabrication processes and commercially available materials, it holds significant promise for device-scale, as well as building thermoregulation applications.

Original languageEnglish (US)
Pages (from-to)669-677
Number of pages9
Issue number5
StatePublished - Mar 1 2024

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering


  • metamaterials
  • nanophotonic design
  • porous polymers
  • radiative cooling
  • superwhite
  • sustainability


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