Flexible electronics is a rapidly expanding research area. Applications include touch screens, electronic paper (e-paper), sensors, radio frequency tags, photovoltaic cells, and electronic textiles. To date, it mainly relies on two fabrication strategies: one in which substrates bearing thousands of Field-effect Transistors (FETs) are bonded to plastic by transfer printing or pick-and-place methods; another in which FETs are prepared directly on the target substrate by several coating, curing and lithographic steps. Rubber stamping, embossing and ink-jet printing reduce the number of such fabrication steps.

Ink-jet printing is one of the most promising techniques for large area fabrication of flexible plastic electronics. A range of components can be printed, such as transistors, photovoltaic devices, organic light emitting diodes (OLEDs), and displays. Ink-jet printing is versatile, involves a limited number of process steps, is amenable for mass production, and can deposit controlled amounts of material.

Graphene Printable Transparent ElectronicsCambridge University researchers demonstrated ink-jet printing as a viable method for large area fabrication of graphene devices. They produce a graphene-based ink by liquid phase exfoliation of graphite in N-Methylpyrrolidone. They used this graphene-based ink to print thin-film transistors, with mobilities up to 95cm2V−1s−1, as well as transparent and conductive patterns, with upto 80% transmittance and 30kilohms sheet resistance. This paves the way to all-printed, flexible and transparent graphene devices on arbitrary substrates.

Liquid phase exfoliated graphene is an ideal and low cost material for the fabrication of transparent conductive inks. This demonstrates the viability of graphene-inks for flexible and transparent electronics.