Surface chemistry of 2D materials is key to controlling the substrate electronic structure and interactions with the environment. Noncovalent functionalization using modified long-chain alkanes to create striped phase monolayers has been widely used on materials such as graphene and highly oriented pyrolytic graphite (HOPG) to functionalize the surface while retaining the highly conjugated electronic structure of the substrate. Developing control over the surface chemistry of other 2D materials such as MoS2, which have useful electronic properties (e.g. native band gaps), would facilitate their application in devices. Noncovalent functionalization of MoS2 has achieved limited success, in part due to lower alkyl chain adsorption enthalpies on MoS2 compared to graphite as well as an increased epitaxial mismatch between the alkyl chain and MoS2 lattice structure. Here, we show that striped-phase diyne phospholipid monolayers on MoS2 exhibit increased stability towards solution processing in comparison with monolayers of single-chain amphiphiles. In monolayers of diyne phospholipids, edge-on adsorption produces monolayers in which alkyl chains form two stacked layers on the substrate. This finding provides a design principle for stabilizing noncovalent alkyl monolayers on substrates to which they adsorb more weakly than on HOPG.

Stabilizing noncovalent monolayers on MoS2 through edge-on adsorption of multi-chain functional alkanes

2019 Fall National Meeting

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