Quantum leap for inkjet-printed graphene

Researchers at Nottingham University of England have made a breakthrough in 3D printing graphene into electronic components with an inkjet printer by adding tiny flakes of this highly conductive 2D material to an ink-like solution.

With the exponential growth in the number of patents involving graphene since its discovery, the limitations of exploiting this new material has seen a number of difficulties, particularly in regard to scalable manufacturing techniques.

The 5.85 million pound (US$7.71 million) Engineering and Physical Sciences Research Council-funded project at Nottingham was carried out by engineers at the Centre for Additive Manufacturing and physicists at the School of Physics and Astronomy.

Published in Advanced Functional Materials, the new study shows that additive manufacturing of 3D printing using inks in which tiny flakes of graphene are suspended provides promising results.

"According to the laws of quantum mechanics, in which the electrons act as waves rather than particles, we found electrons in 2D materials travel along complex trajectories between multiple flakes. It appears as if the electrons hop from one flake to another," said co-author Professor Mark Fromhold, head of the School of Physics and Astronomy.

The team used a range of characterization techniques – including micro-Raman spectroscopy, thermal gravity analysis, a novel 3D orbiSIMS instrument and electrical measurements – to provide detailed structural and functional understanding of inkjet-printed graphene polymers.

Utilizing quantum mechanic modeling, they were also able to pinpoint how electrons move through this 2D material so as to better understand how it can be modified for future use.

"Our results could lead to diverse applications for inkjet-printed graphene-polymer composites and a range of other 2D materials. The findings could be employed to make a new generation of functional optoelectronic devices; for example, large and efficient solar cells; wearable, flexible electronics that are powered by sunlight or the motion of the wearer; perhaps even printed computers," said co-author Dr. Lyudmila Turyanska, from the Centre for Additive Manufacturing.

As graphene is usually made by sequentially exfoliating a single layer of carbon atoms, arranged in a flat sheet to produce tailored structures, the challenge of combining them to make complex sandwich-like materials has been a difficult hurdle, usually requiring deposition of the layers one at a time and by hand.

With the success of an inkjet-graphene printing technique, the team has opted to continue searching for better techniques to control the deposition of the flakes by using polymers to influence the way they align and to try different inks with a range of flake sizes.

The researchers hope to develop more sophisticated computer simulations of the materials and the way they work together in the chance they could develop new ways of mass-manufacturing the devices they prototype.