The chase is on for developing the next piece of technology that can go and be a part of the next smart home—or, at least, if researchers are to be asked about it. From transparent electrodes that can pave the way to new power-generating windows to smart coatings that can help heat and cool buildings, there always seems to be a new development somewhere out there that aims to make the house of the future a little bit more comfortable.
Such is the case with new research from a collaboration between Nanyang Technological University (NTU) Singapore and the Hebrew University of Jerusalem, whose researchers worked together to create a special “switchable” coating that can be applied to windows to enable visible light to pass through without taking the sometimes-unwanted infrared heat with them. Their study was published in the journal ACS Omega.
The researchers recognize that there already exists smart window technology called electrochromic windows; these windows can change their color—and as a result, the nature of the light that passes through them—by applying a current through the setup. Thing is, these setups often only screen visible light, and can oftentimes just let infrared radiation right on through; it’s the radiation that we can’t see, but instead feel as heat.
In order to address this concern, the NTU-HUJ collaboration focused on an inexpensive solution, which is a window coating mixture comprised of a litany of compounds: tungsten trioxide (WO3), tin oxide (SnO2), and neodymium-niobium (Nd-Nb); the mixture can be shortened to a “Nd–Nb Co-doped SnO2/α-WO3 electrochromic material” that just rolls off the tongue.
When no current is passing through, the material lets both visible light and infrared light pass through, making the device usable in winter conditions where much light and heat from the Sun must be retained and utilized. Once the device is turned on, the new electrochromic material blend can let through about 90% of the visible light while also keeping out some 70% of the associated infrared radiation. In short, we have a window that lets light through but keeps the accompanying heat out.
Additional testing also showcased the new material’s resistance to damage and wear induced by repeated on-off cycles, as demonstrated by cycle testing.
Said co-author Dr. Ronn Goei, of NTU: “With the ability to control both infrared radiated heat from the sun and conducted heat passing through the window, we expect this technology to be particularly useful in temperate climates, as building occupants can use it to regulate heat loss or gain according to the needs of the changing seasons, while still enjoying much of the view.”
References
- Coxworth, B. (2021, November 9). Switchable window material stays clear while blocking the sun’s heat. New Atlas. https://newatlas.com/materials/switchable-window-material-infrared-visible-light/
- Goei, R., Ong, A. J., Tan, J. H., Loke, J. Y., Lua, S. K., Mandler, D., Magdassi, S., & Yoong Tok, A. I. (2021). Nd–nb co-doped sno2/α-wo3 electrochromic materials: Enhanced stability and switching properties. ACS Omega, 6(40), 26251–26261. https://doi.org/10.1021/acsomega.1c03260
- Nanyang Technological University Singapore. (2021, November 9). ‘Smart’ window blocks rays without blocking views. Nanyang Technological University Singapore. https://www.ntu.edu.sg/news/detail/smart-window-blocks-rays-without-blocking-views
