Smartphone screens seem to crack at the slightest breeze, but researchers at the University of Sussex might have developed a hardier alternative. The secret ingredient is (as usual) graphene, and when combined with silver nanowires the new material could lead to touchscreens that are tougher, easy to manufacture, more responsive, less power-hungry, and even flex and bend.
Your smartphone screen most likely gets its touch input from a layer of indium tin oxide, but while the material is great for its transparency and conductivity, it's also relatively rare, expensive and fragile. Silver is often used as an alternative but it's also a little on the pricey side, and we've also seen copper crop up in the past.
The Sussex team found that they could greatly reduce the amount of silver used by combining it with graphene – sheets of carbon just one atom thick. To make the screen, the researchers float the graphene film on the surface of water, then pick it up with a rubber stamp and press it on top of a layer of silver nanowire. While this technique sounds like a craft project for now, the team says it lends itself well to being scaled up, using spraying machines or patterned rollers.
"The addition of graphene to the silver nanowire network also increases its ability to conduct electricity by around a factor of ten thousand," says Alan Dalton, head of the team behind the material. "This means we can use a fraction of the amount of silver to get the same, or better, performance. As a result screens will be more responsive and use less power."
According to the researchers, the benefits of using graphene go beyond lowering the cost of touch-sensitive film.
"One of the issues with using silver is that it tarnishes in air," says Matthew Large, lead researcher on the project. "What we've found is that the graphene layer prevents this from happening by stopping contaminants in the air from attacking the silver. What we've also seen is that when we bend the hybrid films repeatedly the electrical properties don't change, whereas you see a drift in the films without graphene that people have developed previously. This paves the way towards one day developing completely flexible devices."
The research was published in the journal Langmuir.
Source: University of Sussex