Broadly-tunable smart glazing using an ultra-thin phase-change material

• Main Authors: Youngblood, Nathan, Talagrand, Clément, Porter, Benjamin, Galante, Carmelo Guido, Kneepkens, Steven, Sarwat, Syed Ghazi, Yarmolich, Dmitry, Bonilla, Ruy S, Hosseini, Peiman, Taylor, Robert, Bhaskaran, Harish
• Format: Journal Article
• Language: English
• Published: 07.11.2019
• Subjects: Physics - Applied Physics; Physics - Optics
• DOI: 10.48550/arxiv.1911.02990

For many applications, a method for controlling the optical properties of a solid-state film over a broad wavelength range is highly desirable and could have significant commercial impact. One such application is smart glazing technology where it is necessary to harvest near-infrared solar radiation in the winter and reflect it in the summer--an impossibility for materials with fixed thermal and optical properties. Here, we experimentally demonstrate a smart window which uses a thin-film coating containing GeTe, a bi-stable, chalcogenide-based phase-change material which can modulate near-infrared absorption while maintaining neutral-colouration and constant transmission of light at visible wavelengths. We additionally demonstrate controlled down-conversion of absorbed near-infrared energy to far-infrared radiation which can be used to heat a building's interior and show that these thin-films also serve as low-emissivity coatings, reducing heat transfer between a building and its external environment throughout the year. Finally, we demonstrate fast, sub-millisecond switching using transparent electrical heaters integrated on glass substrates. These combined properties result in a smart window that is efficient, affordable, and aesthetically pleasing--three aspects which are crucial for successful adoption of green technology.