Potential, Scope and Limitations of Liquid Interface Assembly as a Technique for Synthesizing 2D Thin Films

Solution fabrication of large-area thin films with 2D materials is an active field of study. In this work, we disperse natural graphite and MoS₂ flakes at a heptane-water interface. Individual flakes spread out and arrange themselves as a thin film at the interface, which is then transferred to a glass substrate. This technique allows us to combine the light absorbing properties of MoS₂ with the high conductivity of graphite to make composite films which exhibit photoconductivity. We observe that the flakes like to arrange themselves in a single layer and resist stacking. The conductivity of the resulting film is correlated with its porosity, much like a percolation network of resistors. We find that the technique, while very effective in spreading out these 2D materials into a single layer, does not help with exfoliation at the atomic scale.