Highly Enhanced Photoluminescence of Monolayer MoS₂ in Plasmonic Hybrids with Double-Layer Stacked Ag Nanoparticles

In this work, a feasible method was proposed to prepare MoS2-based plasmonic hybrid systems with high photoluminescence (PL) emission enhancement. The enhancement effect of plasmonic hybrids on the PL emission of MoS2 has been systematically studied on MoS2/Ag spherical nanoparticle (SP) hybrid systems with different architectures by changing the stacking position of Ag SPs. It is demonstrated that the sandwich-like hybrid composed of monolayer MoS2 and dielectric Al2O3 layer between two layers of Ag SPs has the highest PL enhancement. Remarkably, after adding an Al2O3 layer under MoS2, the PL intensity enhancement up to 209 times was achieved in the sandwich-like hybrid system. Compared with the hybrid with single-layer SPs, the sandwich-like hybrid system with double-layer Ag SPs exhibited an obvious blue shift as a result of the selective enhancement of the A0 exciton in MoS2. These results demonstrate that MoS2/Ag SP hybrid nanosystems have significant implications for sensing and photoelectronic devices.