Synergetic photoluminescence enhancement of monolayer MoS surface plasmon resonance and defect repair.

The weak light-absorption and low quantum yield (QY) in monolayer MoS are great challenges for the applications of this material in practical optoelectronic devices. Here, we report on a synergistic strategy to obtain highly enhanced photoluminescence (PL) of monolayer MoS by simultaneously improving the intensity of the electromagnetic field around MoS and the QY of MoS. Self-assembled sub-monolayer Au nanoparticles underneath the monolayer MoS and bis(trifluoromethane)sulfonimide (TFSI) treatment to the MoS surface are used to boost the excitation field and the QY, respectively. An enhancement factor of the PL intensity as high as 280 is achieved. The enhancement mechanisms are analyzed by inspecting the contribution of the PL spectra from A excitons and A trions under different conditions. Our study takes a further step to developing high-performance optoelectronic devices based on monolayer MoS.