Indium-free solution for touch screen materials

New material without indium

One of the most important applications of indium metalas a rare metal is to synthesize indium tin oxide. The compound is known for its optically transparent and electrically conductive properties, making it a key ingredient in touchscreen materials. But indium is scarce, expensive and at risk of becoming "endangered" in the future. Now, researchers at the University of Sydney in Australia have found a potential solution: they have developed a new way to use plasma technology to make indium-free transparent, conductive films that can be manipulated flexibly in a process that uses less power and is environmentally friendly.

The new touch-screen film does not contain plasma, but is manufactured using plasma technology, a new method of tungsten oxide deposition. Using this method, the researchers developed a nanocomposite composed of tungsten oxide and silver that allows the electrochromic device to efficiently and quickly change color according to the user's needs.

Research on new materials

Using a process called plasma sputtering, the researchers created new ultra-thin "sandwich" materials on glass -- a layer of ultra-thin silver sandwigged between two layers of tungsten oxide. The structure is less than 100 nanometers thick.

To make it, the researchers subjected a mixture of argon and oxygen to a powerful electric field until the mixture turned into a plasma state.Plasma is used to bombard a tungsten solid target, separating the atoms from it and treating them as an ultra-thin layer deposited on the glass surface.

The researchers then repeated the process with metallic silver, and finally a third time with silver nanoparticles embedded in tungsten oxide. The whole process takes just a few minutes and produces very little waste, which is cheaper than using indium.The resulting film can be used on any glass surface, such as a mobile phone screen or a window.

The finished plasma film is electrochromic, and unlike the color-changing glasses that react to ambient light, applying a voltage to the film can change its transparency and color.

"Smart Windows coated with new plasma films could be used to block light and, as needed, heat," said Benan Akawan, a research fellow at the University of Sydney's School of Biomedical Engineering and School of Physics.It can also be applied to any glass surface and set to adjust the transparency according to the weather outside."

Researchers say the new indium-free technology has huge potential for making the next generation of touch-screen devices, such as smartphones or e-paper, or for environmentally friendly smart Windows and solar cells.The technology is now ready for commercial use on a much larger scale.