Printed electronics using inks based on graphene and other two-dimensional materials can be used to create large-scale, flexible and wearable devices. However, the complexity of ink formulations and the polycrystalline nature of the resulting thin films have made it difficult to examine charge transport in such devices. Here we report the charge transport mechanisms of surfactant- and solvent-free inkjet-printed thin-film devices based on few-layer graphene (semimetal), molybdenum disulfide (MoS2, semiconductor) and titanium carbide MXene (Ti3C2, metal) by investigating the temperature, gate and magnetic-field dependencies of their electrical conductivity. We find that charge transport in printed few-layer MXene and MoS2 devices is dominated by the intrinsic transport mechanism of the constituent flakes: MXene exhibits a weakly localized 2D metallic behaviour at any temperature, whereas MoS2 behaves as an insulator with a crossover from 3D Mott variable-range hopping to nearest-neighbour hopping around 200 K. Charge transport in printed few-layer graphene devices is dominated by the transport mechanism between different flakes, which exhibit 3D Mott variable-range hopping conduction at any temperature.
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The data that support the findings of this study are available at https://data.hpc.imperial.ac.uk/ and from the corresponding author upon reasonable request.
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F.T. acknowledges support from EPSRC grants EP/P02534X/2, EP/R511547/1 and EP/T005106/1, and the Imperial College Collaboration Kick-Starter grant. E.P., F.G., D.D. and R.S.G. acknowledge support from the MIUR PRIN-2017 program (grant no. 2017Z8TS5B—‘Tuning and understanding quantum phases in 2D materials—Quantum2D’). L.A., K.A.P. and R.S. acknowledge support from the EU H2020 Graphene Flagship Core 3 grant no. 881603. J.M.K. acknowledges support from EPSRC grant EP/P027628/1. V.N., D.S., A.R. and A.Z. acknowledge support from the ERC CoG grant 3D2DPrint and V.N. acknowledges support from SFI Centres AMBER and IForm. A part of the electron microscopy characterization was carried out at the Advanced Microscopy Laboratory (AML) at the AMBER centre, CRANN Institute (https://www.tcd.ie/crann/aml/), Trinity College Dublin, Ireland. AML is a Science Foundation Ireland (SFI)-supported imaging and analysis centre. We acknowledge F. La Barbera (Universitá di Catania) for support in the morphological analysis of the inkjet-printed devices.
The authors declare no competing interests.
Peer review information Nature Electronics thanks Lyudmila Turyanska, Jian Zhu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Piatti, E., Arbab, A., Galanti, F. et al. Charge transport mechanisms in inkjet-printed thin-film transistors based on two-dimensional materials. Nat Electron 4, 893–905 (2021). https://doi.org/10.1038/s41928-021-00684-9
Nature Communications (2022)