Research into simpler graphene production could lead to new flexible tech

15 Mar 2022

Small pieces of graphene on EVA/PET foil. Image: Chalmers University of Technology/Munis Khan

Researchers said the findings could pave the way for a ‘new era’ of flexible electronics, such as portable energy-harvesting devices, electronic skin and wearables.

Researchers in Sweden claim to have achieved high conductivity for a type of graphene that is manufactured in a simpler and cheaper method, which could lead to a “new era” of flexible electronics.

Graphene is a one-atom-thick layer of carbon that is said to be 200 times stronger than steel, yet extremely flexible. It is considered to be one of the world’s thinnest and strongest materials, and there are many potential applications due to its flexibility and conductivity.

Researchers from Chalmers University of Technology in Sweden said a high carrier mobility is one of the “extraordinary properties” that makes graphene useful for electronic devices, but achieving this usually requires complex and expensive fabrication methods.

Carrier mobility is how quickly an electron can move through a metal or semiconductor when pulled by an electric field, which is important to create efficient electronics.

“The high electron mobility of graphene points to great potential for broadband communications and high-speed electronics operating at terahertz switching rates,” researcher Munis Khan said.

In a study published in the journal Nanomaterials, Khan and his team looked at a chemical vapour deposition (CVD) graphene, grown on unpolished copper foil and then transferred to EVA/PET lamination foil by using an office laminator and wet etching of copper.

Photo of Munis Khan standing in front of a building.

Researcher Munis Khan. Image: Chalmers University of Technology

The researchers said they achieved a “surprisingly high charge-carrier mobility” using this method, with the mobility increased by up to eight times after holding the “graphene-on-plastic sandwich” at 60 degrees Celsius for a few hours.

“This finding shows that even cheap and flexible graphene devices can still have an uncompromisingly high mobility,” Khan said. “Our article proposes a straightforward method to fabricate cheap graphene devices on flexible substrates with high carrier mobility, probably only limited by the CVD process and purity of copper.”

The researchers said CVD graphene transferred to EVA/PET is being studied for its use in areas such as portable energy-harvesting devices, electronic skin and wearable electronic devices, which require high flexibility.

The team noted that conventional semiconductors lack the “superior mechanical properties” of graphene, which makes them unsuitable for these applications.

“Our observation will indeed increase the scope of such flexible graphene films in this field,” Khan said. “This could also usher the new era of flexible electronics.”

Khan added that the current challenge is integrating microfabrication techniques to make devices on flexible substrates. “Once such issues are addressed, probably within two to three years, we can start utilising such graphene films to fabricate devices for industrial use,” he said.

There have been many studies looking at the applications of this ‘wonder material’, along with ways to reduce its production costs.

Earlier this year, scientists in Ireland said they had developed a low-cost method to produce graphene ink, which could reduce the production cost of graphene to £20 per litre once scaled up.

Trinity nanoscientist Prof Jonathan Coleman previously created nanocomposites of graphene with polymers including those found in rubber bands and silly putty. Last year, his team created a graphene ink blend with excellent mechanical and electrical properties, giving it potential in the wearables space.

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Leigh Mc Gowran is a journalist with Silicon Republic