Publications

Molybdenum disulfde (MoS2) is an extensively studied two-dimensional layered semiconductor with interesting electronic and optical properties. Monolayer MoS2 features strong light–matter interactions due to its direct bandgap, whereas multilayer MoS2 is an indirect bandgap semiconductor and optically inactive. The molecular intercalation of MoS2 with organic cations ofers a strategy to decouple the interlayer interaction, producing a bulk monolayer material, but is usually accompanied by a heavy electron doping efect that can diminish the intrinsic semiconductor properties or induce a phase transition. Here we report a chemical-dedoping strategy to tailor electron density in molecular-intercalated MoS2, thereby retaining monolayer semiconductor properties. By introducing a poly(vinylpyrrolidone)– bromine complex during the electrochemical intercalation process, we show that bulk monolayer MoS2 thin flm can be produced with decoupled interlayer interaction and reduced electron concentration. The resulting thin flms display strong excitonic emission, 20 and >400 times stronger than the exfoliated monolayer and multilayer material, respectively, high valley polarization and an enhanced photoelectric response. Our study opens a scalable path to large-area bulk monolayer MoS2 thin flms with monolayer-like optical properties and greatly increased optical crosssections, presenting an attractive material platform for both fundamental photophysics studies and scalable optoelectronic applications.