Over the past three decades, printable electronics have mostly relied on carbon-based molecules because in spite of their instability and limited performance, such molecules can easily be turned into printable inks. While there have been numerous attempts to work around those limitations by turning to alternatives like carbon nanotubes or inorganic nanoparticles, so far, none have been successful in finding the right blend of materials. Until now, that is.
Through the collaborative effort of researchers in AMBER Centre (Advanced Materials and BioEngineering Research) at Trinity College, Dublin led by Prof. Jonathan Coleman, a breakthrough that can potentially transform several industries through smart printed devices has been made. Specifically, the team has shown that it is possible to print transistors made up entirely of 2-dimensional nanomaterials (rather than carbon-based molecules). The new fabrication now paves the way for applications that can cheaply print a host of electronic devices from solar cells to LEDs as well as impact industries like the ICT, pharmaceutical, food and beverage, and even travel.
As described by Prof. Coleman: “In the future, printed devices will be incorporated into even the most mundane objects such as labels, posters and packaging. Printed electronic circuitry (constructed from the devices we have created) 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transmit information: for example, milk cartons could send messages to your phone warning that the milk is about to go out-of-date.”
According to the team, what differentiates their 2D nanomaterials from other comparable materials used in the same field is its collective capability to produce more cost-effective and high performance printed devices. Their work also shows that it is possible to combine conducting, semiconducting and insulating 2D nanomaterials in complex electronic devices.
The team used graphene nanosheets as the electrodes, tungsten diselenide as the channel, and boron nitride as the separator. Their printing method was based on Prof. Coleman’s work — using nanomaterials in liquid — which has already been licensed to Samsung and Thomas Swan.
They put their focus on transistors based on their belief that such are the ‘electric switches at the heart of modern computing’. And proving the feasibility of printing transistors now lays the groundwork to print a bunch of other devices using 2D nanosheets.
Of course, the performance of printed transistors is still far below the performance of advanced transistors. But the team is optimistic that there is a wide room for improvement beyond the current state-of-the-art for printed transistors, which is what makes their discovery even more exciting, like a tiny step that can eventually lead to leaps and bounds.
“The findings have recently been published in the journal Science under the title “All-printed thin-film transistors from networks of liquid-exfoliated nanosheets”.