Functionalization of Monolayer MoS₂ with Layered Multimolecular Architectures

Two dimensional van der Waals materials have attracted attention due to their unique properties that arise in the monolayer versus bulk limits. Monolayer MoS2 has been at the forefront of 2D materials due to its broad applicability in catalysis, photovoltaics, and spintronics. To realize the capabilities of MoS2 enabled technology, it is necessary to engineer interfaces where charge carriers can be funneled toward or away from the surface. Molecular systems are a versatile strategy to enable this. Ion-linked molecular architectures have been used previously to circumvent difficult and taxing synthetic methods. Here, we demonstrate the growth of metal ion-linked bilayers (ILBs) on monolayer MoS2 consisting of a first layer spacer (4-mercaptobenzoic acid, MBA) with a Zn(II) ion linked to a fluorophore (BODIPY). Using a combination of Atomic Force Microscopy and Raman spectroscopy, we resolved intrinsic S-vacancies in the MoS2 lattice via S–H bond breaking of MBA. X-ray Photoelectron Spectroscopy confirmed that Zn(II) acetate can coordinate to carboxylate groups on MBA. With photoluminescence microscopy, we determined that BODIPY emission is observable only in the presence of a metal ion, confirming the growth of a multimolecular ion-linked supramolecular assembly on MoS2.