Significantly improved the darkening technology for glass (USA)

A quick push of a button and within a very short time, the previously clear glass darkens. American chemist report that they have significantly improved the darkening technology for glass and the glass clouds is much faster and is dark, almost black. There are many applications.

Significantly improved the darkening technology
Some materials change color and transparency, when a small current flows through them. Photo: Dennis Sheberla

The future of self darkening of glass panes is apparently in the hands of the chemist. A team of three scientists at the Massachusetts of technology (MIT) have been found, as glasses touch darken a way and also again transparent make Institute. The technology is not new, but now the darkening process works much faster and the glass is also darker, almost black. All should help to save on energy costs.

Electrochemical reaction

Photochromic lenses are long time no news more and often in use. But what if you could significantly increase the speed of sound the jars in the Sun, or set yourself a button? In addition, these glasses respond not brightness, but UV radiation, that is to say in the artificial light of the mechanism does not work. Glasses are designed for these cases currently, can change its transparency within seconds by push of a button.

This works electrochemically, because some materials change color and transparency, when a small current flows through them. The process in the microscopically thin coating you can completely reverse and the so-called electrochromic glass becomes transparent again. The MIT Professor made it now Wade for Chemistry Mircea Dincă and his students Khalid Al-Kaabi and Casey, significantly to accelerate the darkening process, which takes some minutes.

Above all ions are accelerated in their movement

The reason for this relative slowness is the movement of electrons and ions. In particular, the ions which are responsible for the color change in the glass, moving rather slowly. To speed up their movement and the general reaction time, scientists have built a porous metal-organic framework that consists of an organic material, and a metallic salt. Such materials, so the researchers would used for 20 years to keep gases inside a structure. The chemist of the with but they have now uses the first time due to their electrical and optical qualities and the glass-coated.

With the new usage of the well-known technique, scientists could solve another problem. Previously, it was difficult or impossible to change the glass from completely transparent to opaque black. That now seems to be succeeded at least in the laboratory. For this, the two complementary colors were mixed green and Red together. The glass of the MIT team now wants to establish a small prototype, could be so extremely fast extremely dark, where between the input and switching off, no power is required to keep the glass in the respective State.

Application for example in aircraft cabin Windows

As application not only glasses come into question. The researchers themselves, for example, mention the cabin window of a Boeing 787, which are equipped already with elektrochromem glass and can be darkened at the push of button. “But if it is laying the switch, it takes a few minutes, until the Windows are dark,” says Mircea Dincă. It should be faster, especially when the Sun is shining brightly through the cabin window.

Also, greater energy savings are possible, for example in buildings, which were equipped with appropriate window panes. It takes a push and it could darken an entire side of the building. Dincă sees more applications in small displays that work with electronic ink, as well as E-books.