Highly suppressed solar absorption in a daytime radiative cooler designed by genetic algorithm

Sunae So; Younghwan Yang; Soomin Son; Dasol Lee; Dongwoo Chae; Heon Lee; Junsuk Rho

doi:10.1515/nanoph-2021-0436

Highly suppressed solar absorption in a daytime radiative cooler designed by genetic algorithm

Sunae So
, Younghwan Yang
, Soomin Son
, Dasol Lee
, Dongwoo Chae
, Heon Lee
, Junsuk Rho^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

69 Citations (Scopus)

Abstract

Here, we report a selective multilayer emitter for eco-friendly daytime passive radiative cooling. The types of materials and thickness of up to 10 layers of the multilayer structure are optimized by a genetic algorithm. The passive radiative cooler is designed to mainly target low solar absorption, which allows sub-ambient cooling under direct sunlight. We used a custom objective function in the solar region to achieve high-performance daytime radiative cooling to minimize solar absorption. The designed structure minimizes solar absorption with an average absorptivity of 5.0% in the solar region (0.3-2.5 μm) while strongly emitting thermal radiation with an average emissivity of 86.0% in the atmospheric transparency window (8-13 μm). The designed and fabricated structure achieves daytime net cooling flux of 84.8 W m-2 and 70.6 W m-2, respectively, under the direct AM 1.5 solar irradiation (SI) (total heat flux of 892 W m-2 in the 0.3-2.5 μm wavelength region). Finally, we experimentally demonstrate a passive radiative cooling of the fabricated selective emitter through a 72-hour day-night cycle, showing an average and maximum temperature reduction of 3.1 °C and 6.0 °C, respectively. Our approach provides additional degrees of freedom by designing both materials and thickness and thereby is expected to allow high-performance daytime radiative cooling.

Original language	English
Pages (from-to)	2107-2115
Number of pages	9
Journal	Nanophotonics
Volume	11
Issue number	9
DOIs	https://doi.org/10.1515/nanoph-2021-0436
Publication status	Published - 2022 Apr 1

Bibliographical note

Funding Information:
Research funding: This work was financially supported by the POSCO-POSTECH-RIST Convergence Research Center program funded by POSCO, and the National Research Foundation (NRF) grants (NRF-2019R1A2C3003129, CAMM-2019M3A6B3030637, NRF-2019R1A5A8080290, NRF-2018M3D1A1058997) funded by the Ministry of Science and ICT of the Korean government. S.S. and D.C. acknowledge the NRF Global Ph.D. fellowships (NRF-2017H1A2A1043322 and NRF-2019H1A2A1076622), respectively, funded by the Ministry of Education (MOE) of the Korean government. Y.Y. acknowledges the Hyundai Motor Chung Mong-Koo fellowship, and the NRF fellowship (NRF-2021R1A6A3A13038935) funded by the MOE of the Korean government.

Publisher Copyright:
© 2021 Sunae So et al., published by De Gruyter, Berlin/Boston.

Keywords

computational optimization
multilayer structures
radiative cooling
selective emitters

ASJC Scopus subject areas

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

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10.1515/nanoph-2021-0436

Cite this

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title = "Highly suppressed solar absorption in a daytime radiative cooler designed by genetic algorithm",

abstract = "Here, we report a selective multilayer emitter for eco-friendly daytime passive radiative cooling. The types of materials and thickness of up to 10 layers of the multilayer structure are optimized by a genetic algorithm. The passive radiative cooler is designed to mainly target low solar absorption, which allows sub-ambient cooling under direct sunlight. We used a custom objective function in the solar region to achieve high-performance daytime radiative cooling to minimize solar absorption. The designed structure minimizes solar absorption with an average absorptivity of 5.0\% in the solar region (0.3-2.5 μm) while strongly emitting thermal radiation with an average emissivity of 86.0\% in the atmospheric transparency window (8-13 μm). The designed and fabricated structure achieves daytime net cooling flux of 84.8 W m-2 and 70.6 W m-2, respectively, under the direct AM 1.5 solar irradiation (SI) (total heat flux of 892 W m-2 in the 0.3-2.5 μm wavelength region). Finally, we experimentally demonstrate a passive radiative cooling of the fabricated selective emitter through a 72-hour day-night cycle, showing an average and maximum temperature reduction of 3.1 °C and 6.0 °C, respectively. Our approach provides additional degrees of freedom by designing both materials and thickness and thereby is expected to allow high-performance daytime radiative cooling.",

keywords = "computational optimization, multilayer structures, radiative cooling, selective emitters",

author = "Sunae So and Younghwan Yang and Soomin Son and Dasol Lee and Dongwoo Chae and Heon Lee and Junsuk Rho",

note = "Funding Information: Research funding: This work was financially supported by the POSCO-POSTECH-RIST Convergence Research Center program funded by POSCO, and the National Research Foundation (NRF) grants (NRF-2019R1A2C3003129, CAMM-2019M3A6B3030637, NRF-2019R1A5A8080290, NRF-2018M3D1A1058997) funded by the Ministry of Science and ICT of the Korean government. S.S. and D.C. acknowledge the NRF Global Ph.D. fellowships (NRF-2017H1A2A1043322 and NRF-2019H1A2A1076622), respectively, funded by the Ministry of Education (MOE) of the Korean government. Y.Y. acknowledges the Hyundai Motor Chung Mong-Koo fellowship, and the NRF fellowship (NRF-2021R1A6A3A13038935) funded by the MOE of the Korean government. Publisher Copyright: {\textcopyright} 2021 Sunae So et al., published by De Gruyter, Berlin/Boston.",

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doi = "10.1515/nanoph-2021-0436",

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T1 - Highly suppressed solar absorption in a daytime radiative cooler designed by genetic algorithm

AU - So, Sunae

AU - Yang, Younghwan

AU - Son, Soomin

AU - Lee, Dasol

AU - Chae, Dongwoo

AU - Lee, Heon

AU - Rho, Junsuk

N1 - Funding Information: Research funding: This work was financially supported by the POSCO-POSTECH-RIST Convergence Research Center program funded by POSCO, and the National Research Foundation (NRF) grants (NRF-2019R1A2C3003129, CAMM-2019M3A6B3030637, NRF-2019R1A5A8080290, NRF-2018M3D1A1058997) funded by the Ministry of Science and ICT of the Korean government. S.S. and D.C. acknowledge the NRF Global Ph.D. fellowships (NRF-2017H1A2A1043322 and NRF-2019H1A2A1076622), respectively, funded by the Ministry of Education (MOE) of the Korean government. Y.Y. acknowledges the Hyundai Motor Chung Mong-Koo fellowship, and the NRF fellowship (NRF-2021R1A6A3A13038935) funded by the MOE of the Korean government. Publisher Copyright: © 2021 Sunae So et al., published by De Gruyter, Berlin/Boston.

PY - 2022/4/1

Y1 - 2022/4/1

N2 - Here, we report a selective multilayer emitter for eco-friendly daytime passive radiative cooling. The types of materials and thickness of up to 10 layers of the multilayer structure are optimized by a genetic algorithm. The passive radiative cooler is designed to mainly target low solar absorption, which allows sub-ambient cooling under direct sunlight. We used a custom objective function in the solar region to achieve high-performance daytime radiative cooling to minimize solar absorption. The designed structure minimizes solar absorption with an average absorptivity of 5.0% in the solar region (0.3-2.5 μm) while strongly emitting thermal radiation with an average emissivity of 86.0% in the atmospheric transparency window (8-13 μm). The designed and fabricated structure achieves daytime net cooling flux of 84.8 W m-2 and 70.6 W m-2, respectively, under the direct AM 1.5 solar irradiation (SI) (total heat flux of 892 W m-2 in the 0.3-2.5 μm wavelength region). Finally, we experimentally demonstrate a passive radiative cooling of the fabricated selective emitter through a 72-hour day-night cycle, showing an average and maximum temperature reduction of 3.1 °C and 6.0 °C, respectively. Our approach provides additional degrees of freedom by designing both materials and thickness and thereby is expected to allow high-performance daytime radiative cooling.

AB - Here, we report a selective multilayer emitter for eco-friendly daytime passive radiative cooling. The types of materials and thickness of up to 10 layers of the multilayer structure are optimized by a genetic algorithm. The passive radiative cooler is designed to mainly target low solar absorption, which allows sub-ambient cooling under direct sunlight. We used a custom objective function in the solar region to achieve high-performance daytime radiative cooling to minimize solar absorption. The designed structure minimizes solar absorption with an average absorptivity of 5.0% in the solar region (0.3-2.5 μm) while strongly emitting thermal radiation with an average emissivity of 86.0% in the atmospheric transparency window (8-13 μm). The designed and fabricated structure achieves daytime net cooling flux of 84.8 W m-2 and 70.6 W m-2, respectively, under the direct AM 1.5 solar irradiation (SI) (total heat flux of 892 W m-2 in the 0.3-2.5 μm wavelength region). Finally, we experimentally demonstrate a passive radiative cooling of the fabricated selective emitter through a 72-hour day-night cycle, showing an average and maximum temperature reduction of 3.1 °C and 6.0 °C, respectively. Our approach provides additional degrees of freedom by designing both materials and thickness and thereby is expected to allow high-performance daytime radiative cooling.

KW - computational optimization

KW - multilayer structures

KW - radiative cooling

KW - selective emitters

UR - https://www.scopus.com/pages/publications/85119423362

U2 - 10.1515/nanoph-2021-0436

DO - 10.1515/nanoph-2021-0436

M3 - Article

AN - SCOPUS:85119423362

SN - 2192-8606

VL - 11

SP - 2107

EP - 2115

JO - Nanophotonics

JF - Nanophotonics

IS - 9

ER -

Highly suppressed solar absorption in a daytime radiative cooler designed by genetic algorithm

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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