arXiv subjects

Robyn Worsley

Publications and source records attributed to Robyn Worsley.

3 recordsLinked to original sources

arXiv2020

Low-voltage 2D materials-based printed field-effect transistors for integrated digital and analog electronics on paper

Paper is the ideal substrate for the development of flexible and environmentally sustainable ubiquitous electronic systems, which, combined with two-dimensional materials, could be exploited in many Internet-of-Things applications, ranging from wearable electronics to smart packaging. Here we report high-performance MoS2 field-effect transistors on paper fabricated with a channel-array approach, combining the advantages of two large-area techniques: chemical vapor deposition and inkjet-printing.The first allows the pre-deposition of a pattern of MoS2; the second, the printing of dielectric layers, contacts, and connections to complete transistors and circuits fabrication. Average ION/IOFF of 8 x 10^3 (up to 5 x 10^4) and mobility of 5.5 cm2 V-1 s-1 (up to 26 cm2 V-1 s-1) are obtained. Fully functional integrated circuits of digital and analog building blocks, such as logic gates and current mirrors, are demonstrated, highlighting the potential of this approach for ubiquitous electronics on paper.

physics.app-ph↗

arXiv2019

Water-based and Inkjet Printable Inks made by Electrochemically Exfoliated Graphene

Inkjet printable graphene inks are very attractive for applications in flexible and foldable electronics, such as wearable electronics and the Internet of Things. However, the ink preparation is still very time consuming as high concentrations can be achieved only with prolonged sonication (>24 hours) or with expensive setups. Here we demonstrate a water-based inkjet printable ink made from electrochemically exfoliated graphene. A printable and stable (> 1 month) ink with concentration of ~2.25 mg mL-1 was formulated in less than 5 hrs, using two successive steps: first exfoliation and dispersion of large graphene flakes (> 5 um) followed by 1 hour tip-sonication to reduce the flake size below 1 um, as required for the material to be ejected by the nozzle. The formulated ink contains more than 75% single- and few-layers (i.e. less than 2 nm in thickness) graphene flakes with an average lateral size of 740 nm. Thermal annealing allows to achieve high C/O ratio (>10), which translates into one of the highest electrical conductivity (~3.91 x 104 S m-1) reported so far for solution-processed graphene, without the use of any harsh chemical processing.

physics.app-ph↗

arXiv2018

All-2D Material Inkjet-Printed Capacitors: Towards Fully-Printed Integrated Circuits

A well-defined insulating layer is of primary importance in the fabrication of passive (e.g. capacitors) and active (e.g. transistors) components in integrated circuits. One of the most widely known 2-Dimensional (2D) dielectric materials is hexagonal boron nitride (hBN). Solution-based techniques are cost-effective and allow simple methods to be used for device fabrication. In particular, inkjet printing is a low-cost, non-contact approach, which also allows for device design flexibility, produces no material wastage and offers compatibility with almost any surface of interest, including flexible substrates. In this work we use water-based and biocompatible graphene and hBN inks to fabricate all-2D material and inkjet-printed capacitors. We demonstrate an areal capacitance of 2.0 \pm 0.3 nF cm^(-2) for a dielectric thickness of \sim 3 μm and negligible leakage currents, averaged across more than 100 devices. This gives rise to a derived dielectric constant of 6.1 \pm 1.7. The inkjet printed hBN dielectric has a breakdown field of 1.9 \pm 0.3 MV cm^(-1). Fully printed capacitors with sub-/mu m hBN layer thicknesses have also been demonstrated. The capacitors are then exploited in two fully printed demonstrators: a resistor-capacitor (RC) low-pass filter and a graphene-based field effect transistor.

physics.app-ph↗