Photoluminescence control of WSe₂ monolayers integrated with plasmon nanobumps via strain engineering

This work presents a hybrid system for photoluminescence control, consisting of a tungsten diselenide monolayer (1L-WSe₂) integrated with an array of plasmonic gold nanobumps fabricated by femtosecond laser printing. This technique allows precise tuning of the plasmonic resonance in these structures by controlling their geometry. It is shown that this integration provides a dual mechanism for enhancing and controlling photoluminescence (PL). First, the plasmonic resonance significantly amplifies the PL emission near the nanobump due to exciton-plasmon interaction. Second, the deformation of the WSe₂ monolayer on the nanobump leads to a red shift of the PL peak, resulting from modification of the bandgap. A key feature of this system is the ability to control the spectrum by selecting the pump wavelength: changing the excitation energy affects the correlation between the neutral exciton (X⁰) and the low-energy dark exciton/trion (Xᴰ/ᵀ) states. Low-temperature microspectroscopy further revealed a deformation-induced redistribution of intensity from the neutral exciton (X⁰) to low-energy states, including the dark exciton/trion complex (Xᴰ/ᵀ). These results establish a foundation for a platform of spectrally tunable light sources based on hybrid exciton-plasmon-strain interactions, which offers a pathway for the advancement of nanophotonics and the development of next-generation optoelectronic devices.