In a groundbreaking advancement, researchers at North Carolina State University, led by Veronica Augustyn and in collaboration with Delia Milliron from the University of Texas at Austin, have unveiled a material that is set to redefine the way we interact with our environment. Published in ACS Photonics, their study, titled “Dual-Band Electrochromism in Hydrous Tungsten Oxide,” introduces a material for next-generation dynamic windows capable of shifting between three states: transparent, infrared-blocking, and tinted.
Dynamic windows are not a novel concept; traditionally, they shift between clear and dark states based on electrochromism, changing opacity in response to an electric stimulus. However, this latest research transcends the binary, offering a tri-state solution. Veronica Augustyn, the Jake and Jennifer Hooks Distinguished Scholar in Materials Science and Engineering at NC State, emphasizes that this isn’t just about more options; it’s about enhancing energy efficiency while maintaining natural light and visibility.
The magic ingredient? Water. When bound within the crystalline structure of tungsten oxide to form tungsten oxide hydrate, it exhibits a hitherto unknown behavior. Commonly used in dynamic windows, tungsten oxide transitions from transparent to dark when injected with lithium ions and electrons. But with tungsten oxide hydrate, researchers have discovered they can fine-tune the wavelengths of light being blocked.
Initially, the material enters a ‘heat blocking’ phase, allowing visible light but obstructing infrared, effectively cooling the building without sacrificing light. Further injection of lithium ions and electrons pushes the material into a ‘dark’ phase, blocking both visible and infrared wavelengths. Jenelle Fortunato, the paper’s first author and a postdoctoral fellow at NC State, explains that water’s presence in the crystalline structure prevents deformation, accommodating more lithium ions and leading to the unique dual-mode functionality.
This discovery isn’t just a step forward for smart windows; it’s a leap. Delia Milliron notes the potential acceleration in commercial products’ development, offering enhanced features previously unattainable. Beyond just smart windows, the revelation about structural water’s role might spark innovation across various fields, particularly in energy storage and conversion materials.
As we look to a future where buildings can ‘tune’ their transparency for optimal comfort and energy efficiency, it’s clear that the intersection of material science and technology is paving the way for a more sustainable, intelligent world.
Original Article: Matt Shipman, North Carolina State University. “Material would allow users to ‘tune’ windows to block targeted wavelengths of light.” ACS Photonics (2023). DOI: 10.1021/acsphotonics.3c00921. Link.