The Electrical and Morphological Characteristics of Networks of Mechanically Exfoliated Nanosheets

Solution-processed nanosheet networks show great promise for the field of printed electronics due to their inherent scalability and competitive electrical properties. However, recent progress has allowed for the production of nanosheet networks by a dry, roll-to-roll mechanical exfoliation process. While this method is promising for producing low-cost devices, the electrical properties of such networks are poorly understood and will require elucidation to enable optimization. Herein, the morphological and electrical properties of mechanically exfoliated networks of MoS₂ are investigated. 3D images reveal that the networks show low porosity (11 ± 2%) and a high degree of in-plane alignment. The network conductivity is dependent on annealing temperature and reaches a maximum of 11 ± 0.6 S m^-1, when annealed at 300 °C. The networks show n-type behavior with a mobility of 0.8 ± 0.1 cm² V^-1 s^-1. Electrical impedance spectroscopy measurements reveal that this relatively low network mobility is caused by a combination of high inter-nanosheet resistance (890 ± 150 kΩ) and low intrinsic mobility of the nanosheets (7 ± 2 cm² V^-1 s^-1). Temperature-dependent conductivity measurements show activated hopping as the internanosheet conduction mechanism near room temperature, with an activation energy of 61.9 ± 0.2 meV.