Spectrally Selective Nanoparticle Mixture Coating for Passive Daytime Radiative Cooling

Dongwoo Chae, Hangyu Lim, Sunae So, Soomin Son, Sucheol Ju, Wonjoong Kim, Junsuk Rho, Heon Lee

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Passive daytime radiative cooling, which is a process that removes excess heat to cold space as an infinite heat sink, is an emerging technology for applications that require thermal control. Among the different structures of radiative coolers, multilayer- and photonic-structured radiative coolers that are composed of inorganic layers still need to be simple to fabricate. Herein, we describe the fabrication of a nanoparticle-mixture-based radiative cooler that exhibits highly selective infrared emission and low solar absorption. Al2O3, SiO2, and Si3N4 nanoparticles exhibit intrinsic absorption in parts of the atmospheric transparency window; facile one-step spin coating of a mixture of these nanoparticles generates a surface with selective infrared emission, which can provide a more powerful cooling effect compared to broadband emitters. The nanoparticle-based radiative cooler exhibits an extremely low solar absorption of 4% and a highly selective emissivity of 88.7% within the atmospheric transparency window owing to the synergy of the optical properties of the material. The nanoparticle mixture radiative cooler produces subambient cooling of 2.8 °C for surface cooling and 1.0 °C for space cooling, whereas the Ag film exhibits an above-ambient cooling of 1.1 °C for surface cooling and 3.4 °C for space cooling under direct sunlight.

Original languageEnglish
Pages (from-to)21119-21126
Number of pages8
JournalACS Applied Materials and Interfaces
Volume13
Issue number18
DOIs
Publication statusPublished - 2021 May 12

Keywords

  • atmospheric transparency window
  • nanoparticle mixture
  • passive daytime radiative cooling
  • selective emitter
  • subambient cooling

ASJC Scopus subject areas

  • Materials Science(all)

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