The breakthrough by scientists at Sussex University is also claimed to promise devices that use less energy, are more responsive, and do not tarnish in the air.
Smartphone screens are currently made with indium tin oxide, which is brittle and expensive. The primary constituent, indium, is also a rare metal and is ecologically damaging to extract. Silver, which has been shown to be the best alternative to indium tin oxide, is also expensive.
Prof Alan Dalton, from the School of Mathematical and Physical Sciences at Sussex University said that the research combines silver nanowires and graphene for the first time.
“What’s exciting about what we’re doing is the way we put the graphene layer down,” he said. “We float the graphene particles on the surface of water, then pick them up with a rubber stamp…and lay it on top of the silver nanowire film in whatever pattern we like.
“And this breakthrough technique is inherently scalable. It would be relatively simple to combine silver nanowires and graphene in this way on a large scale using spraying machines and patterned rollers. This means that brittle mobile phone screens might soon be a thing of the past.
“The addition of graphene to the silver nanowire network also increases its ability to conduct electricity by around a factor of ten thousand. 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.”
The research is published in the American Chemical Society journal Langmuir.
Dr Matthew Large, lead researcher on the project within the School of Mathematical and Physical Sciences at Sussex University said:
“Although silver is also a rare metal, like indium, the amount we need to coat a given area is very small when combined with graphene. Since graphene is produced from natural graphite – which is relatively abundant - the cost for making a touch sensor drops dramatically.
“One of the issues with using silver is that it tarnishes in air. 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.”
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