Flexible touchscreens could be printed like newspaper

Australian researchers have developed an ultrathin and ultraflexible electronic material, able to be printed and rolled out like newspaper, for the touchscreens of the future. The work was led by RMIT University and has been published in the journal Nature Electronics.

As explained by lead researcher Dr Torben Daeneke, most mobile phone touchscreens are made of a transparent material — indium tin oxide (ITO) — that is very conductive but also very brittle.

“We’ve taken an old material and transformed it from the inside to create a new version that’s supremely thin and flexible,” said Dr Daeneke, an Australian Research Council DECRA Fellow at RMIT.

“You can bend it, you can twist it, and you could make it far more cheaply and efficiently than the slow and expensive way that we currently manufacture touchscreens.

“Turning it two-dimensional also makes it more transparent, so it lets through more light.

“This means a mobile phone with a touchscreen made of our material would use less power, extending the battery life by roughly 10%.”

To create the new type of atomically thin ITO, researchers from RMIT, UNSW, Monash University and the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET) used a thin film common in mobile phone touchscreens and shrank it from 3D to 2D, using a liquid metal printing approach.

An indium-tin alloy is heated to 200°C, where it becomes liquid, and then rolled over a surface to print off nanothin sheets of indium tin oxide. These 2D nanosheets have the same chemical make-up as standard ITO but a different crystal structure, giving them new mechanical and optical properties.

The touch-responsive technology is 100 times thinner than existing touchscreen materials and so pliable it can be rolled up into a tube. It is readily compatible with existing electronic technologies and, because of its incredible flexibility, could potentially be manufactured through roll-to-roll (R2R) processing just like a newspaper.

It also absorbs just 0.7% of light, compared with the 5–10% of standard conductive glass. To make it more electronically conductive, just add more layers.

“There’s no other way of making this fully flexible, conductive and transparent material aside from our new liquid metal method,” Dr Daeneke said.

“It was impossible up to now — people just assumed that it couldn’t be done.”

The product is also easier to create than the transparent thin film material used in standard touchscreens, which is manufactured in a slow, energy-intensive and expensive batch process conducted in a vacuum chamber. Dr Daeneke noted, “The beauty is that our approach doesn’t require expensive or specialised equipment — it could even be done in a home kitchen.”

The research team has now used the new material to create a working touchscreen as a proof of concept, and has applied for a patent for the technology. The material could also be used in many other optoelectronic applications, such as LEDs and touch displays, as well as potentially in future solar cells and smart windows.

“We’ve shown it’s possible to create printable, cheaper electronics using ingredients you could buy from a hardware store, printing onto plastics to make touchscreens of the future,” Dr Daeneke said.

“We’re excited to be at the stage now where we can explore commercial collaboration opportunities and work with the relevant industries to bring this technology to market.”

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