Three researchers at the Massachusetts Institute of Technology (MIT) have developed a self-shading window that switches quickly from transparent to dark.
The smart window is made from electrochromic materials, which can change their properties under the influence of an electrical voltage. Compared to photochromic materials (those found in eyeglasses and lenses that darkens upon exposure to bright light), electrochromic materials respond and change opacity faster.
Electrochromic materials have been used in windows of the Boeing 787 aircraft, although they also take a few minutes to change color.
In their paper published in the journal Chem, the MIT team reported that they were able to make the process work faster by using a porous compound called metal-organic frameworks (MOFs), which can conduct electrons and ions at high speeds, allowing for a quick overall reaction speed.
The research team had worked on MOFs in their prior studies and had made a material that could turn from clear to shades of blue or green. In order to accomplish a coating that can turn from clear to almost black, they blended two complementary colors (green and red).
While most existing eletrochromic materials require continuous voltage input to work, this smart window — once it has changed its color — can maintain its state with little to no power, and will only need electricity to turn it back to its former state (clear or opaque).
Mircea Dinca, the MIT professor of chemistry of the trio, said in a statement that “the new windows have the potential to do much more than just preventing glare. These could lead to pretty significant energy savings by drastically reducing the need for air conditioning in buildings with many windows in hot climates. You could just flip a switch when the sun shines through the window, and turn it dark, or even automatically make that whole side of the building go dark all at once.”