Dimmable windows, in one form or another, have been with us for several years now. We've seen examples such as the manually-adjustable SPD-Smart motorcoach windows, the energy-harvesting Smart Energy Glass product, and the RavenWindow, which darkens or lightens according to the outside temperature. According to researchers from Korea's Soongsil University and Korea Electronics Technology Institute, however, such windows can be expensive, don't work properly for long enough, and require toxic substances in their manufacturing process. The team claims to have developed a system of their own, that has none of these drawbacks.

Scientists Ho Sun Lim, Jeong Ho Cho, Jooyong Kim and Chang Hwan Lee utilized a polyelectrolyte copolymer, ions reacting with counterions (ions that have a charge opposite to that of other given ions, resulting in electrical neutrality), and solvents such as methanol. The result was dimmable glass that was inexpensive and less toxic to manufacture, while offering robust performance. It is also said to change tint quickly, going from being opaque to almost completely clear within seconds.

As with other such products, the Korean window glass could be used to block sunlight and save on air conditioning costs in the summer, while allowing sunlight it to save on heating bills in the winter.

The research was recently published in the journal ACS Nano.