Vivid Colored Cooling Structure Managing Full Solar Spectrum via Near-Infrared Reflection and Photoluminescence

Chae, Dongwoo; Lee, Sang Yeop; Lim, Hangyu; Son, Soomin; Ha, Jisung; Park, Jaein; Park, Jun Hyeok; Oh, Soong Ju; Lee, Heon

doi:10.1021/acsami.3c08790

Cited by 10 publications

References 59 publications

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Neutral‐Colored Transparent Radiative Cooler by Tailoring Solar Absorption with Punctured Bragg Reflectors

Ko,

Noh,

Chae

et al. 2024

Adv Funct Materials

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Daytime radiative cooling (DRC) has emerged as a promising method for temperature reduction of surfaces exposed to sunlight, without energy consumption. Despite advancements in DRC design, existing reflector‐based methodologies often lack transparency because of visible reflection, hindering the widespread application of this technology using glass. Efforts to address this challenge have led to the development of transparent radiative cooling (TRC), although efficient cooling during daylight remains challenging because of the dominant solar energy absorption. This paper proposes a novel TRC design comprising a polydimethylsiloxane (PDMS) emitter atop a transparent dual‐reflector structure. An optimized Bragg reflector (OBR) and a 90 µm‐hole‐punctured Ag window screen reflector (WR) are used to reflect band A of the near‐infrared (NIR) spectrum (0.74 < λ < 1.4 µm) and the overall solar spectrum, respectively. During the daytime, the proposed TRC lowers the temperature by 22.1 °C through the transparent dual reflector system, compared to a PDMS‐coated glass. Thus, this approach optimizes the balance between solar reflection and visibility using a dual reflector, offering an optimal solution for applications requiring both cooling and transparency.

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Neutral‐Colored Transparent Radiative Cooler by Tailoring Solar Absorption with Punctured Bragg Reflectors

Ko,

Noh,

Chae

et al. 2024

Adv Funct Materials

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Fluorescence‐Enabled Colored Bilayer Subambient Radiative Cooling Coatings

Ma,

Fu,

Liu

et al. 2024

Advanced Optical Materials

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Passive daytime radiative cooling has emerged as a promising green technology for the thermal management of buildings, vehicles, textiles, and electronics. Typically, both high solar reflectance and high thermal emissivity are prerequisites to achieve sufficient daytime cooling. However, colored radiative cooling materials are facing the dilemma of introducing visible light absorption, leading to challenges in balancing cooling and aesthetic demands. Here, three colored bilayer radiative cooling coatings, each comprised of a white base layer and a colored top layer with fluorescence enhancement are fabricated. Three phosphors (Sr2Si5N8:Eu2+, Y3Al5O12:Ce3+, and (Ba,Sr)SiO4:Eu2+) are employed with respective photoluminescence quantum yields (PLQYs) of 81%, 95.8%, and 91.0% as the colored pigment in the top layer. To mitigate the contradiction between coloration and solar reflectance, SiO2 microspheres are introduced into the top layer and utilize their Mie‐resonance‐based multiple scattering to increase the photoluminescent (PL) properties of the phosphors, which jointly boosts the effective solar reflectance (ESR) of the top layer. As a result, the three bilayer coatings exhibit soft colors while achieving subambient cooling with temperature drops of up to 1.5 °C. This fluorescence‐enhancement strategy may pave the way for preparing highly efficient radiative cooling coatings with tunable colors.

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Scalable Hierarchical‐Colored Passive Cooling Metapaint for Outdoor Facility

Yang,

Zhou,

Liu

et al. 2024

EcoMat

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The temperature of metal‐based facilities rises significantly under high outdoor solar irradiation, leading to serious safety accidents. The application of active cooling technology poses challenges due to its high energy consumption, especially in complex outdoor environments. Passive cooling devices with high solar reflection and thermal emission can continuously cool objects under sunlight. However, the white or silvery passive cooling devices do not meet the need for aesthetics and specific demands. Here, we present a hierarchical metapaint for outdoor facilities that simultaneously achieve vibrant color and passive cooling ability. The top layer selectively absorbs visible wavelengths to display desired colors, while the underlayer boosts the reflection of near‐to‐short wavelength infrared (NSWIR) light to prevent solar heating. The metapaint‐coated metal is resistant to high and low temperatures, acidic and alkaline environments, and simulated seawater. It also has satisfactory anti‐fouling properties. When compared to metal coated without commercial paint, the hierarchical passive cooling paint (metapaint) coated metal can cool up to 9.7°C and 17.1°C. The metapaint has excellent passive cooling performance, attributed to its broad‐spectrum selective regulation function. Our work offers a simple, inexpensive, and scalable approach to reduce cooling energy usage and promote a low‐carbon lifestyle. image

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Vivid Colored Cooling Structure Managing Full Solar Spectrum via Near-Infrared Reflection and Photoluminescence

Cited by 10 publications

References 59 publications

Neutral‐Colored Transparent Radiative Cooler by Tailoring Solar Absorption with Punctured Bragg Reflectors

Neutral‐Colored Transparent Radiative Cooler by Tailoring Solar Absorption with Punctured Bragg Reflectors

Fluorescence‐Enabled Colored Bilayer Subambient Radiative Cooling Coatings

Scalable Hierarchical‐Colored Passive Cooling Metapaint for Outdoor Facility

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