CMD30 FisMat2023 - Submission - View

Abstract title: Charge transport mechanisms in inkjet-printed thin-film transistors based on ion-gated molybdenum disulfide
Submitting author: Erik Piatti
Affiliation: Department of Applied Science and Technology, Politecnico di Torino
Affiliation Address: corso Duca degli Abruzzi 24, I-10129 Torino
Country: Italy
Other authors and affiliations: Adrees Arbab (Department of Chemistry, Imperial College London, London, United Kingdom), Francesco Galanti (Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy), Tian Carey (Department of Chemistry, Imperial College London, London, United Kingdom), Luca Anzi (L-NESS, Department of Physics, Politecnico di Milano, Como, Italy), Dahnan Spurling (Trinity College Dublin, Dublin, Ireland), Ahin Roy (Trinity College Dublin, Dublin, Ireland), Ainur Zhussupekova (Trinity College Dublin, Dublin, Ireland), Kishan A. Patel (L-NESS, Department of Physics, Politecnico di Milano, Como, Italy), Jong M. Kim (Department of Engineering, University of Cambridge, Cambridge, United Kingdom), Dario Daghero (Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy), Roman Sordan (L-NESS, Department of Physics, Politecnico di Milano, Como, Italy), Valeria Nicolosi (Trinity College Dublin, Dublin, Ireland), Renato S. Gonnelli (Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy), Felice Torrisi (Department of Chemistry, Imperial College London, London, United Kingdom and Department of Physics and Astronomy, University of Catania, Catania, Italy)
Abstract
Printed electronics using inks based on graphene and other two-dimensional materials can be used to create large-scale, flexible and wearable devices [1]. Although charge transport mechanisms in isolated flakes of 2D materials – including molybdenum disulfide (MoS2) [2,3] – have been extensively investigated, the mechanism in inkjet-printed films of 2D-material inks remains poorly understood. This is because their structure consists of a large number of highly crystalline flakes assembled together in a three-dimensional (3D) network [1], and is more complex than that of isolated flakes. As a result, charge transport depends on an interplay between charge-carrier propagation within each flake (intra-flake transport) and propagation from one flake to the surrounding flakes in the network (inter-flake transport) [4]; it also introduces additional disorder with respect to that found in isolated flakes in the form of sharp boundaries between the different printed flakes in the network. Previous attempts at probing the low-temperature conductivity in printed thin films of semiconducting transition metal dichalcogenides have suggested that charge transport occurs via some kind of hopping mechanism, but have failed to reach a conclusion on the specific model [5,6]. In this Talk, I will discuss our recent work [7] where we unveil the charge transport mechanisms of surfactant- and solvent-free inkjet-printed thin-film devices based on ion-gated MoS2 flakes by investigating the temperature and gate voltage dependencies of their electrical conductivity. Surprisingly, our results demonstrate that charge transport in the printed few-layer MoS2 devices is dominated by the intrinsic transport mechanism of the constituent flakes: the films behave as insulators with a temperature-induced crossover from 3D Mott variable-range hopping (VRH) to nearest-neighbour hopping (NNH) around 200 K, and a gate-induced crossover from NNH to a quasi-metallic conduction close to room temperature. Our findings pave the way to the reliable design of more complex printed electronics with 2D material inks.

References
[1] F. Torrisi and T. Carey, Nano Today 23, 73-96 (2018).
[2] H. Qiu et al., Nat. Commun. 4, 2642 (2013).
[3] J. Xue et al., RSC Adv. 9, 17885-17890 (2019).
[4] D. Akinwande, Nat. Nanotechnol. 12, 287-288 (2017).
[5] A. G. Kelly et al., Science 356, 69-73 (2017).
[6] S. Ippolito et al., Nat. Nanotechnol. 16, 592-598 (2021).
[7] E. Piatti et al., Nat. Electron. 4, 893-905 (2021).