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This study numerically investigates how hollow gold nanocylindrical cavities can selectively enhance the photoluminescence of either the A or B exciton in monolayer molybdenum disulfide (MoS2), two closely spaced excitonic transitions separated by only tens of meV. Using finite-difference time-domain simulations and a photoluminescence-rate framework, the researchers show that tuning the cavity aspect ratio aligns the localized surface plasmon resonance with a chosen exciton, while spacer thickness and refractive index control near-field coupling. Under optimized conditions, photoluminescence enhancements of 143.85 and 87.27 were achieved for the A and B excitons respectively, along with exciton-selective peak ratios up to 2.4 times higher than those of bare MoS2.
Why it matters
Selective control over individual excitonic transitions in atomically thin semiconductors has direct relevance to valleytronic devices, nanoscale light sources, and wavelength-encoded optical sensing, where distinguishing spectrally proximate emission peaks is a persistent technical challenge.
arXiv:2603.07732v2 Announce Type: replace
Abstract: Spectral control of closely spaced excitonic transitions is central to valleytronic photonics, nanoscale light sources, and wavelength-encoded sensing. In monolayer molybdenum disulfide (MoS2), the A and B excitons are separated by only tens of meV, making selective excitonic emission control both fundamentally important and technologically challenging. Here, we numerically investigate plasmon-enhanced excitonic emission from monolayer MoS2 coupled to vertically oriented hollow gold nanocylindrical cavities through a dielectric spacer. Finite-difference time-domain simulations combined with a photoluminescence-rate framework enable separate evaluation of excitation enhancement, radiative decay modification, nonradiative quenching, and excitonic charge generation. By tuning the cavity aspect ratio, the localized surface plasmon resonance is selectively aligned with either the A- or B-exciton transition, while the spacer thickness and refractive index regulate near-field coupling and the local density of optical states. Under optimized conditions, the excitation rate is enhanced by up to 4.34-fold and the radiative decay rate by more than 40-fold, yielding photoluminescence enhancements of 143.85 and 87.27 for the A and B excitons, respectively. The cavity also redistributes the relative excitonic peak intensities, producing exciton-selective peak ratios up to 2.4 times higher than those of bare MoS2. These results establish hollow plasmonic nanocavities as geometry-tunable platforms for exciton-selective emission and charge-generation control in atomically thin semiconductors.
Source: Geometry-Controlled Exciton Selectivity in Monolayer MoS2 Using Plasmonic Hollow Nanocavities