Biphasic Self-Assembly of Chemically-Exfoliated MoS2 Monolayers into a MoS2/C Heterostructured Thin Film

Chemically exfoliated transition metal dichalcogenides are promising materials for optoelectronic applications, but their practical use is often limited by low in-plane electrical conductivity. Here, we report a biphasic self-assembly strategy for fabricating large-area MoS2/C heterostructured thin films from colloidal MoS2 nanosheets. By balancing electrostatic repulsion and van der Waals attraction through controlled protonation at a polar-nonpolar solvent interface, MoS2 nanosheets spontaneously assemble into continuous films. Structural characterization confirms the formation of 3-4 layer thick MoS2 films with intercalated hydrocarbon species that are converted into nanocrystalline carbon layers upon annealing. These intercalated carbon layers provide charge transport pathways across MoS2 nanosheet junctions, resulting in room-temperature in-plane electrical conductivity of 2.92 S/m after annealing at 500 °C. This biphasic self-assembly approach provides a simple and scalable route to uniform 2D heterostructured thin films with enhanced macroscale charge transport.