Scientists at Lawrence Berkeley National Laboratory and Autonomous University of Barcelona have recently developed a kind of smart glass with adjustable transparency. This “Smart Glass” can change from opaque to transparent like a chameleon and can adjust itself according to different wavelengths. Therefore, it can help improve building’s energy efficiency through big widows made of it and help housekeepers get out of their routine chores related to curtains.

The smart glass is made of niobate, mixed with nanometer sized crystals of indium tin oxide (ITO). As the mixed material has the properties of glass, it is called a “glass”, but all its molecules are in disarray without a clear pattern just like those in a liquid.

Dissolving the niobate in water, adding the crystals of indium tin oxide and then evaporating the solution by heating, the researchers find that this mixture can form an amorphous solid. After putting the niobate glass at the top of an electrode, adding a layer of electrolyte and a second electrode to it, the scientists find that the glass changes its transparency as the voltage of the electrode increases. The glass becomes completely transparent at a voltage of 4 V, and can block near-infrared rays at 2.3 V, visible rays and near-infrared rays at 1.5 V. Why? This is because electrical charges change the structure of nanocrystals and make them block the rays of specific wavelengths.

For its real-world application, first the research team has to find a good electrode material, since the electrolyte must be a solid. And then they can coat the surface of normal glass with this smart glass for use in buildings.