A smart screen for cooling and sun protection
by Riko Seibo
Tokyo, Japan (SPX) Nov 07, 2024
A collaborative research effort between POSTECH and Korea University has led to the development of an innovative transparent radiative cooling film. Professors Junsuk Rho and his team from POSTECH's Mechanical, Chemical, and Electrical Engineering departments, alongside PhD candidates Byoungsu Ko and Jaebum Noh, worked with Professor Heon Lee and PhD candidate Dongwoo Chae from Korea University's Department of Materials Science and Engineering to create a film that mimics an insect screen to manage solar heat and reduce indoor temperatures. The study was featured in 'Advanced Functional Materials'.

Radiative cooling, which enables objects to naturally release heat without energy input, has been challenging to implement effectively in transparent films for use on surfaces like glass. Existing films often allow solar heat to pass through, reducing their cooling efficiency.

To counter this, the researchers devised a multi-layered film using a perforated silver (Ag) substrate, a Bragg mirror, and a polydimethylsiloxane (PDMS) coating. The Bragg mirror reflects near-infrared light, the main contributor to solar heating. The perforated silver substrate, designed with micrometer-scale holes, maintains transparency akin to an insect screen while allowing light transmission. The PDMS layer, a silicon-based material, promotes the emission of far-infrared radiation, optimizing the film's cooling function.

Tests demonstrated that glass coated with this advanced film maintained a temperature 22.1C cooler than glass with only PDMS coating.

"This technology is ready for mass production and has significant potential in architecture and environmental applications," stated Professor Junsuk Rho. He emphasized, "It effectively dissipates heat and reduces energy consumption, positioning it as a key technology for a sustainable future."

This research was supported by POSCO Holdings' N.EX.T IMPACT Metasurface-based Planar Optics Technology Lab, along with the Leading Research Lab initiative from the Ministry of Science and ICT and the National Research Foundation of Korea.

Research Report:Neutral-Colored Transparent Radiative Cooler by Tailoring Solar Absorption with Punctured Bragg Reflectors

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