TY - JOUR
T1 - Maxwell-Garnett permittivity optimized micro-porous PVDF/PMMA blend for near unity thermal emission through the atmospheric window
AU - Wong, Ross Y.M.
AU - Tso, C. Y.
AU - Fu, S. C.
AU - Chao, Christopher Y.H.
N1 - Funding Information:
This research is funded by the Hong Kong Research Grant Council via General Research Fund (GRF) account 16200518 .
Funding Information:
We acknowledge Professor Wang Fuqiang affiliated with Harbin Institute of Technology at Weihai for sharing numeric values of the dielectric function of PVDF. We acknowledge University Research Facility in Materials Characterization and Device Fabrication in The Hong Kong Polytechnic University for technical support. This research is funded by the Hong Kong Research Grant Council via General Research Fund (GRF) account 16200518.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/12
Y1 - 2022/12
N2 - Owing to excellent solar reflectivity and sky window emissivity, disordered heterogenous materials, including filler-abundant matrices, paints, and coatings, as well as foam-like, fiber-stacked and composite porous structures, form a major class for efficient passive radiative cooling. Contrary to well-established empirical understanding, this work offers a generalized analytical overview of their macroscopic thermo-optical properties from the microscopic electromagnetic perspective of Maxwell-Garnett effective medium theory. With the family of micro-porous poly(vinylidene-fluoride)/poly(methyl-methacrylate) blends as a representative example, procedures for tailoring mid-infrared spectral emissivity via effective permittivity are outlined. Theoretical framework and design scheme are validated by finite difference time domain simulation and Fourier transform infrared spectrometry. It is shown that poly(vinylidene-fluoride) and poly(methyl-methacrylate) form a pair of complementary constitutive materials for near unity thermal emission through the atmospheric window. Optimized binary polymeric blend, prepared by spray-coating method, features a window emissivity of 98% and realizes nocturnal radiative cooling with a temperature reduction of 6.8 °C and a cooling power of 94 W/m2 in an outdoor field investigation. It can serve as a promising bifunctional material for simultaneous radiative heat dissipation and capacitive energy storage, which meets the demand for nocturnal, radiative cooling aided thermoelectricity generation and storage potential.
AB - Owing to excellent solar reflectivity and sky window emissivity, disordered heterogenous materials, including filler-abundant matrices, paints, and coatings, as well as foam-like, fiber-stacked and composite porous structures, form a major class for efficient passive radiative cooling. Contrary to well-established empirical understanding, this work offers a generalized analytical overview of their macroscopic thermo-optical properties from the microscopic electromagnetic perspective of Maxwell-Garnett effective medium theory. With the family of micro-porous poly(vinylidene-fluoride)/poly(methyl-methacrylate) blends as a representative example, procedures for tailoring mid-infrared spectral emissivity via effective permittivity are outlined. Theoretical framework and design scheme are validated by finite difference time domain simulation and Fourier transform infrared spectrometry. It is shown that poly(vinylidene-fluoride) and poly(methyl-methacrylate) form a pair of complementary constitutive materials for near unity thermal emission through the atmospheric window. Optimized binary polymeric blend, prepared by spray-coating method, features a window emissivity of 98% and realizes nocturnal radiative cooling with a temperature reduction of 6.8 °C and a cooling power of 94 W/m2 in an outdoor field investigation. It can serve as a promising bifunctional material for simultaneous radiative heat dissipation and capacitive energy storage, which meets the demand for nocturnal, radiative cooling aided thermoelectricity generation and storage potential.
KW - Disordered heterogeneous materials
KW - Effective medium theory
KW - Electromagnetism
KW - Light-matter interaction
KW - Radiative cooling
KW - Thermo-optics
UR - http://www.scopus.com/inward/record.url?scp=85138081645&partnerID=8YFLogxK
U2 - 10.1016/j.solmat.2022.112003
DO - 10.1016/j.solmat.2022.112003
M3 - Journal article
AN - SCOPUS:85138081645
SN - 0927-0248
VL - 248
JO - Solar Energy Materials and Solar Cells
JF - Solar Energy Materials and Solar Cells
M1 - 112003
ER -