Graphene ink could lead to bendable tablet!
While the inkjet-printed graphene was demonstrated in earlier tests, the graphene patterns in the new study are about 250 times more conductive than previous patterns.
"This could be a step toward low-cost, foldable electronics," the researchers said.
“Graphene has a unique combination of properties that is ideal for next-generation electronics, including high electrical conductivity, mechanical flexibility, and chemical stability,” said Mark Hersam, professor of materials science and engineering at Northwestern’s McCormick School of Engineering and Applied Science. “By formulating an inkjet-printable ink based on graphene, we now have an inexpensive and scalable path for exploiting these properties in real-world technologies.”
Inkjet printing has previously been explored as a method for fabricating transistors, solar cells, and other electronic components. It is inexpensive, capable of printing large areas, and can create patterns on a variety of substrates, making it an attractive option for next-generation electronics.
Inkjet printing with graphene — ultra-thin sheets of carbon with exceptional strength and conductivity — is extremely promising, but it has remained a challenge because it is difficult to harvest a sufficient amount of graphene without compromising its electronic properties.
The Northwestern researchers said they have developed a new method for mass-producing graphene that maintains its conductivity and can be carried out at room temperature using ethanol and ethyl cellulose to exfoliate graphite. This relatively clean process minimises residues and results in a powder with a high concentration of nanometer-sized graphene flakes, which is then mixed into a solvent to create the ink.
The researchers demonstrated printing the ink in multiple layers, each 14nm thick, to create precise patterns. The ink’s conductivity remains virtually unchanged, even when bent to a great degree, suggesting that graphene inks could be used to create foldable electronic devices in the future.