Large-Scale Manipulation of Monolayer MoS₂ Photoluminescence via Size-Tunable Plasmonic Nanoparticles: Implications for Information Encoding and Optical Anti-Counterfeiting

Tailoring light-matter interactions in single-layer molybdenum disulfide (MoS2) is vital for its applications in advanced photonic functionalities with tunable optical outputs. Although significant efforts have been devoted to the manipulation of localized photoluminescence (PL) via well-defined plasmonic nanostructures or single shape-controlled nanoantenna, subtle tailoring of optical emission still remains unexplored for wafer-scale production. Here, a tunable PL enhancement of monolayer MoS2 via size-controllable Au nanoparticle (Au NP) arrays is reported. A centimeter-scale Au NP monolayer is prepared by simple annealing of the Au film with different thicknesses, enabling a size-dependent plasmon resonance with a wide range and prominent near-field enhancement. PL emission intensity can be effectively manipulated and enhanced by an elaborate regulation of nanoparticle dimensions. The resonance wavelength and PL enhancement of Au NPs with particular sizes were also in good agreement with the finite-difference time-domain (FDTD) simulations. Tuning the plasmon resonances approximately to a 633 nm excitation light can effectively boost the PL intensity up to 75-fold, which is attributed to the optimally enhanced adsorption of pump laser and the radiative decay rate. A double-layer stacked Au NP structure based on the optimal nanoparticle size is also implemented to realize a further 1.7-fold increase of PL emission derived from the enhanced near-field intensity within the plasmon gaps. The proposed LSPR-tunable plasmonic platform provides flexibility for choosing the operating wavelength of two-dimensional (2D) material-based photonic/optoelectronic devices, as well as a path for a reconfigurable information encoding platform with highly tailorable signal output.