Plasmonic Grating on Monolayer MoS ₂ for Strong Photoluminescence Enhancement and Ultrasensitive Surface-Enhanced Raman Scattering (SERS) Detection

Monolayer MoS₂, a key 2D transition metal dichalcogenide (TMDC), offers strong potential for next-generation optoelectronic devices due to its direct bandgap and tunable optical properties. However, its ultrathin structure results in inherently weak light-matter interactions and limited photoluminescence (PL) output. Here, we demonstrate a scalable strategy for enhancing the optical response of monolayer MoS₂ using plasmonic nanoresonators patterned via capillary-force-assisted assembly of the thermoresponsive polymer poly(ε-caprolactone) (PCL), eliminating complex nanofabrication. Subsequent deposition of plasmonic metals (Au, Ag, Al) forms well-defined resonator arrays, enabling sequential fabrication of multiple patterns on a single layer. Optimized Au gratings (818 nm width, 2.6 nm thickness) achieved over 390-fold PL enhancement through efficient exciton-plasmon coupling. Moreover, the crossbar-type Au-Au gratings on MoS₂ exhibited remarkable surface-enhanced Raman scattering (SERS) sensitivity, enabling detection of rhodamine 6G down to 10^-18 M. This practical approach significantly amplifies light-matter interactions in 2D materials, advancing their integration into flexible photonic, sensing, and optoelectronic systems.