2D nanomaterials create printed electronics

Researchers have fabricated printed transistors consisting entirely of two-dimensional nanomaterials for the first time, in a breakthrough which combines exciting electronic properties with the potential for low-cost production.

The research was led by Professor Jonathan Coleman from materials science research centre AMBER, hosted at Trinity College Dublin. Professor Coleman claims that the future will see printed devices incorporated into “even the most mundane objects such as labels, posters and packaging”.

“Printed electronic circuitry will allow consumer products to gather, process, display and transmit information: for example, milk cartons could send messages to your phone warning that the milk is about to go out of date,” he said.

Printable electronics have developed over the last 30 years based mainly on printable carbon-based molecules. While these molecules can easily be turned into printable inks, such materials are somewhat unstable and have performance limitations. There have been attempts to surpass these obstacles using alternative materials, such as carbon nanotubes or inorganic nanoparticles, but these materials have also shown limitations in either performance or in manufacturability.

Professor Coleman believes that 2D nanomaterials can compete with the materials currently used for printed electronics, with the capability to “yield more cost-effective and higher performance printed devices”. Together with the groups of Professor Georg Duesberg (AMBER) and Professor Laurens Siebbeles (TU Delft, the Netherlands), he sought to demonstrate the potential of these materials.

The team used Professor Coleman’s scalable method of producing 2D nanomaterials in liquids to combine graphene nanosheets, or flakes, as the electrodes with two other nanomaterials — tungsten diselenide and boron nitride — as the channel and separator, to form an all-printed, all-nanosheet, working transistor. Each nanosheet is just a few nanometres thick but hundreds of nanometres wide.

“We felt that it was critically important to focus on printing transistors, as they are the electric switches at the heart of modern computing,” said Professor Coleman.

Writing in the journal Science, the study authors explained that nanosheets made from different materials have electronic properties that can be conducting (in the case of graphene), insulating (boron nitride) and semiconducting (tungsten diselenide), and thus include all the building blocks of electronics. Liquid processing is especially advantageous in that it yields large quantities of high-quality 2D materials in a form that is easy to process into inks.

The study therefore provides the potential to print circuitry at extremely low cost, opening the path for industry to print a host of electronic devices — from solar cells to LEDs — with applications from interactive smart food and drug labels to next-generation banknote security and e-passports.

“We believe this work opens the way to print a whole host of devices solely from 2D nanosheets,” said Professor Coleman.

Image caption: Professor Jonathan Coleman from AMBER holding a transistor printed with layered materials. Image credit: AMBER, Trinity College Dublin.