Graphene ink created for ink-jet printing of electronic components

November 25, 2011 by Lin Edwards, Phys.org report
Dark field optical micrograph of inkjet printed drops on a) plasma cleaned, b) pristine and c) HMDS treated substrate. Scale: 20µm. d) SEM micrograph of printed pattern. Image from arXiv:1111.4970v1 [cond-mat.mtrl-sci]

(PhysOrg.com) -- A group of UK scientists has created a graphene ink that can be used to ink-jet print electronic devices such as thin film transistors.

Professor of Nanotechnology, Andrea Ferrari, and colleagues from the Engineering Department at the University of Cambridge have developed a method of creating a graphene ink that can be used with a modified ink-jet printer. Graphene consists of a of carbon only one atom thick, and has great advantages over polymer inks because of its greater and . Electronic components such as thin film transistors (TFTs) can already be created using ink-jet printing with ferro-electric polymer inks, but the performance of such components is poor and they are too slow for many applications.

Beginning with flakes of pure , the team exfoliated layers of graphene using exfoliation (LPE), which consists of sonication of the graphite in the presence of a solvent, N-Methylpyrrolidone (NMP). The graphene layers were ultracentrifuged and then filtered to remove any particles large enough (>1μm in diameter) to block the ink-jet printer heads. The graphene flakes were then used as the basis for a graphene-polymer ink, which was printed, using a modified ink-jet printer, onto Si/SiO2 substrates and the transparent substrate borosilicate glass. The final step in the process was annealing at high temperature to remove the solvent.

They demonstrated the new transparent graphene ink by using it to ink-jet print , which they made by printing the graphene ink on Si/SiO2 wafers. They used chromium-gold pads to define the source and drain contacts, and they then printed a layer of an organic polymer, PQT-12, on top.

The team achieved promising results at least comparable to current inks. They achieved mobilities of up to around 95cm2V−1s−1, about 80% transmittance and 30kohm sheet resistance. Non-graphene polymer inks typically achieve mobilities of less than 0.5cm2V−1s−1, while adding carbon nanotubes can increase this to around 50cm2V−1s−1.

The results should improve as the method is refined and enhanced. Their successful first demonstration paves the way for the development of flexible and cheap electronics that can be printed on a wide variety of substrates. Devices printed using graphene inks could include wearable computers, electrical paper, sensors, electronic tags, and flexible touch screens.

The paper is available online from arXiv.org.

Explore further: Korean researchers use graphene to create transparent loudspeakers

More information: Ink-Jet Printed Graphene Electronics, arXiv:1111.4970v1 [cond-mat.mtrl-sci] arxiv.org/abs/1111.4970

Abstract
We demonstrate ink-jet printing as a viable method for large area fabrication of graphene devices. We produce a graphene-based ink by liquid phase exfoliation of graphite in N-Methylpyrrolidone. We use it to print thin-film transistors, with mobilities up to~95cm^2V^(-1)s(-1), as well as transparent and conductive patterns, with~80 % transmittance and~30kOhm/sq sheet resistance. This paves the way to all-printed, flexible and transparent graphene devices on arbitrary substrates.

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6 comments

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rawa1
1 / 5 (3) Nov 25, 2011
The size and quality of graphene flakes must be very low, if they can pass the filter. It's rather graphite ink (i.e. chinese black ink) than graphene ink and it has nothing to do with graphene electronics, which is using carefully fabricated omnilayers.
Isaacsname
not rated yet Nov 25, 2011
jeez man, did you read the paper ?, ..it's free. They describe the LPE process right on the 1st page.

http://arxiv.org/...70v1.pdf
antialias_physorg
5 / 5 (2) Nov 25, 2011
jeez man, did you read the paper ?, ..it's free.

You can't go around bothering people with facts.

That's un-american, that is.
TehDog
5 / 5 (1) Nov 26, 2011
I've been waiting for a development like this for a few years. Add this tech to 3-D printers. I can't even begin to imagine all the possibilities.
onesourcecomponents
not rated yet Dec 17, 2011
This is what we have been waiting for. It opens up so many potentials for printing.
Callippo
1 / 5 (1) Dec 17, 2011
jeez man, did you read the paper ?, ..it's free
Yes and it doesn't counterargue my objection at least a bit. Graphene works just because it's monolayer of graphite. If you have many monolayers stacked without geometry control, it's just graphite ink without any particular electronic property. The line of pencil drawing has the same electronic properties. It's simply conductive ink. A number of such conductive inks exist based on metallic nanoparticles and they're working a way better because of their higher conductivity.

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