UCLA

The development of graphene and the nanotechnology revolution brought new interest in Layered transition metal dichalcogenides (TMDs). First explored in the 1960s, these TMDs are a subject of interest due to their wide range of material properties form semiconductor, metals, to superconductor. Through intercalation chemistry, there is additional flexibility to tune the materials’ parameters to the desired property. Naturally semiconducting, Group 6 TMDs (i.e. MoS2) have the most potential for future electronic application. Yet these Group 6 TMDs are also the most chemically inert. While over 240 organic-TMD complexes have been made reported for Group 4 (i.e. TiS2) and Group 5 (i.e. TaS2) TMDs, for 50 years, organic complexes of Group 6 TMDs remained unexplored.

With the goal of tailoring the properties of Group 6 TMDs, we followed three different experimental approaches. We begin by pursuing liquid phase exfoliation to produce few/mono layer products and use contact angle measurement to infer the thermodynamic of the exfoliated materials in mixed solvents. We expanded a pen-paper vibrational model of 2H-MoS2 to analyze the vibrational spectra of WS2-xSex alloy with a tunable optical gap. Inspired by Lithium based intercalation methods, we propose a new and direct electrochemical intercalation route to produce Organic-MoS2 complexes using quaternary ammonium compounds. We use the same electrochemical concept and show that the theory is sufficiently robust, allowing intercalation onto Layered Black Phosphorus (BP).