Open AccessHighly‐Scattering Cellulose‐Based Films for Radiative Cooling
Author(s) -
JaramilloFernandez Juliana,
Yang Han,
Schertel Lukas,
Whitworth Guy L.,
Garcia Pedro D.,
Vignolini Silvia,
SotomayorTorres Clivia M.
Publication year - 2022
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202104758
Subject(s) - materials science , thermal emittance , radiative transfer , absorption (acoustics) , radiative cooling , cellulose , irradiance , optoelectronics , optics , chemical engineering , composite material , thermodynamics , physics , beam (structure) , engineering
Passive radiative cooling (RC) enables the cooling of objects below ambient temperature during daytime without consuming energy, promising to be a game changer in terms of energy savings and CO 2 reduction. However, so far most RC surfaces are obtained by energy‐intensive nanofabrication processes or make use of unsustainable materials. These limitations are overcome by developing cellulose films with unprecedentedly low absorption of solar irradiance and strong mid‐infrared (mid‐IR) emittance. In particular, a cellulose‐derivative (cellulose acetate) is exploited to produce porous scattering films of two different thicknesses, L ≈ 30 µm (thin) and L ≈ 300 µm (thick), making them adaptable to above and below‐ambient cooling applications. The thin and thick films absorb only≈ 5 % ${\approx}5\%$ of the solar irradiance, which represents a net cooling power gain of at least 17 W m −2 , compared to state‐of‐the‐art cellulose‐based radiative‐cooling materials. Field tests show that the films can reach up to ≈5 °C below ambient temperature, when solar absorption and conductive/convective losses are minimized. Under dryer conditions (water column = 1 mm), it is estimated that the films can reach average minimum temperatures of ≈7–8 °C below the ambient. The work presents an alternative cellulose‐based material for efficient radiative cooling that is simple to fabricate, cost‐efficient and avoids the use of polluting materials.