This is the accepted version of the paper. This version of the publication may differ from the final published version. Permanent repository link: http://openaccess.city.ac.uk/13049/ Link to published version: http://dx. 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 2 V −1 s −1 , as well as transparent and conductive patterns, with∼80% transmittance and∼30kΩ/ sheet resistance. This paves the way to all-printed, flexible and transparent graphene devices on arbitrary substrates.

Ink-jet printing is an important process for placing active electronics on plastic substrates. We demonstrate ink-jet printing as a viable method for large area fabrication of carbon nanotube ͑CNT͒ thin film transistors ͑TFTs͒. We investigate different routes for producing stable CNT solutions ͑"inks"͒. These consist of dispersion methods for CNT debundling and the use of different solvents, such as N-methyl-2-pyrrolidone. The resulting printable inks are dispensed by ink-jet onto electrode bearing silicon substrates. The source to drain electrode gap is bridged by percolating networks of CNTs. Despite the presence of metallic CNTs, our devices exhibit field effect behavior, with effective mobility of ϳ0.07 cm 2 / V s and ON/OFF current ratio of up to 100. This result demonstrates the feasibility of ink-jet printing of nanostructured materials for TFT manufacture.

Polymer capacitive pressure sensors based on a dielectric composite layer of zinc oxide nanowire and poly(methyl methacrylate) show pressure sensitivity in the range of 2.63 × 10(-3) to 9.95 × 10(-3) cm(2) gf(-1). This represents an increase of capacitance change by as much as a factor of 23 over pristine polymer devices. An ultralight load of only 10 mg (corresponding to an applied pressure of ∼0.01 gf cm(-2)) can be clearly recognized, demonstrating remarkable characteristics of these nanowire-polymer capacitive pressure sensors. In addition, optical transmittance of the dielectric composite layer is approximately 90% in the visible wavelength region. Their low processing temperature, transparency, and flexible dielectric film makes them a highly promising means for flexible touching and pressure-sensing applications.

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Nanocomposite thin film transistors (TFTs) based on nonpercolating networks of single-walled carbon nanotubes (CNTs) and polythiophene semiconductor [poly[5,5′-bis(3-dodecyl-2-thienyl)-2,2′-bithiophene] (PQT-12)] thin film hosts are demonstrated by ink-jet printing. A systematic study on the effect of CNT loading on the transistor performance and channel morphology is conducted. With an appropriate loading of CNTs into the active channel, ink-jet printed composite transistors show an effective hole mobility of 0.23 cm2 V−1 s−1, which is an enhancement of more than a factor of 7 over ink-jet printed pristine PQT-12 TFTs. In addition, these devices display reasonable on/off current ratio of 105–106, low off currents of the order of 10 pA, and a sharp subthreshold slope (<0.8 V dec−1). The work presented here furthers our understanding of the interaction between polythiophene polymers and nonpercolating CNTs, where the CNT density in the bilayer structure substantially influences the morphology and transistor performance of polythiophene. Therefore, optimized loading of ink-jet printed CNTs is crucial to achieve device performance enhancement. High performance ink-jet printed nanocomposite TFTs can present a promising alternative to organic TFTs in printed electronic applications, including displays, sensors, radio-frequency identification (RFID) tags, and disposable electronics.