Tarnish – Proof Films for Flexible Displays, Touch Screens

It could also aid improving computing power, affecting both the transition of information within a silicon chip and the layering of the chip itself through metamaterial superlenses. By linking the silver with a small amount of aluminum, the U-M scientists identified that it was feasible to produce exceptionally sleek, smooth layers of silver that are resistant to tarnishing. They applied an anti-reflective layering to make one thin metal layer up to 92.4 percent transparent.

The group revealed that the silver coating could guide light about 10 times as far as other metal based waveguides, a property that could make it useful for efficient computing. And they layered the silver films into a metamaterial hyperlens that could be employed to prepare defense patterns with feature sizes a fraction of what is feasible with ordinary ultraviolet techniques, on silicon chips, for example.

Screens of all sorts required transparent electrodes to regulate which pixels are lit up, but touchscreens are specifically dependent on them. A modern touch screen is prepared of a transparent conductive layer covered with a non-conductive layer. It senses electronic changes where a conductive object like a finger is pressed against the screen.

“The transparent conductor market has been dominated to this day by one single substance,” says L. Jay Guo, a lecturer of electronic engineering and computer science. This substance, indium tin oxide, is projected to become costly as demand for touch screens continues to grow, there are relatively few known sources of indium, Guo says. “Before, it was very cost-effective. Now, the price is rising sharply,” he says.

The ultrathin layer could make silver a worthy successor. Usually, it is impossible to make a regular layer of silver less than 15 nanometers thick, or roughly 100 silver atoms. Silver has a potential to cluster together in small islands rather than extend into an even layering coating,” says Guo. In addition to their ability to serve as transparent conductors for touch screens, the sleek silver layers offer two more tricks, both having to do with silver’s unparalleled potential to shift visible and infrared light waves along its surface.

The light waves shrink and travel as so-called surface plasmon polaritons, revealing up as oscillations in the concentration of electrons on the surface of silver. Such oscillation encodes the frequency of the light, preserving it so that it can emerge on the other side.

While optical fibers cannot scale down to the size of copper wires on present day’s computer chips, plasmonic waveguides could enable data to travel in optical rather than electrical form for faster data. As a waveguide, the smooth silver film could transport the surface plasmons over a centimeter enough to get by, inside a computer chip. Such lenses can image objects that are smaller than the wavelength of light that would blur in an optical microscope.