New touchscreen material is ultra-thin and ultra-flexible

Researchers have developed an ultra-thin, ultra-flexible, transparent electronic material that can be printed and rolled out like newspaper for touchscreens of the future. This touch-responsive technology is 100 times thinner than existing touchscreen materials and so pliable it can be rolled up like a tube.

To create the new conductive sheet, a team led by researchers at RMIT University in Australia took a thin film of indium-tin oxide (ITO), a transparent material commonly used in cell phone touchscreens, and shrunk it from three dimensions to two dimensions using liquid metal chemistry. The nano-thin sheets are readily compatible with existing electronic technologies, and because of their incredible flexibility could potentially be manufactured through roll-to-roll (R2R) processing just like a newspaper.

The research, which involved collaborators from the University of New South Wales (UNSW), Monash University and the ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), all in Australia, is reported in a paper in Nature Electronics.

According to lead researcher Torben Daeneke, a research fellow at RMIT University, while ITO is transparent and very conductive, it is 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," he said.

"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 (2D) also makes it more transparent, so it lets through more light. This means a cell phone with a touchscreen made of our material would use less power, extending the battery life by roughly 10%."

The current way of manufacturing ITO for use in standard touchscreens is a slow, energy-intensive and expensive batch process, conducted in a vacuum chamber.

"The beauty is that our approach doesn't require expensive or specialized equipment – it could even be done in a home kitchen," Daeneke said. "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."

To create this new type of atomically thin ITO, the researchers used a liquid metal printing approach. This involves heating an indium-tin alloy to 200°C, where it becomes liquid, and then rolling it over a surface to print off nano-thin sheets. These 2D nano-sheets have the same chemical composition as standard ITO but a different crystal structure, giving them exciting new mechanical and optical properties.

As well as being fully flexible, the new type of ITO absorbs just 0.7% of light, compared with 5–10% for standard conductive glass. To make it more electronically conductive, you just add more layers.

According to Daeneke, it's a pioneering approach that overcomes a challenge once considered unsolvable. "There's no other way of making this fully flexible, conductive and transparent material aside from our new liquid metal method," he said. "It was impossible up to now – people just assumed that it couldn't be done."

The research team have already used the new ITO material to create a working touchscreen, as a proof-of-concept, and have applied for a patent on 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'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," Daeneke said.

This story is adapted from material from RMIT University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.