Transition metal dichalcogenides such as molybdenum disulfide (MoS2) are layered materials of great interest due to their interesting thickness-dependent properties and potential for optoelectronic devices. MoS2 can be prepared in dispersion by liquid phase exfoliation, size selected by liquid cascade centrifugation and deposited by vacuum filtration, spray deposition and printing techniques. Here, the dependence of the electrical conductivity of MoS2 nanosheet networks on the average lateral size is investigated. Size-selected dispersions are characterised by statistical atomic force microscopy and UV-visible extinction spectroscopy using established metrics. We find that network conductivity increases as nanosheet size decreases, suggesting that nanosheet packing dominates over the increasing density of inter-nanosheet junctions. The conductivity in the networks of the smallest nanosheets reaches 10-3 S/m, a thousandfold increase on that of the larger nanosheets reported in the literature. This conductivity enhancement is understood in terms of nanosheet packing and porosity, enabling their development towards applications in printed optoelectronic devices.

Size-dependent porosity defines conductivity in liquid-exfoliated nanosheet networks

ACS Spring 2022

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