Temperature-Dependent Plasmon–Exciton Interactions in Hybrid Au/MoSe 2 Nanostructures

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Combining localized surface plasmons and confined excitons in hybrid metallic/semiconductor nanostructures is a promising route toward the manipulation of the light-matter interaction at the nanoscale and the generation of novel technological applications. In this context, we investigate the interference between plasmonic and excitonic resonances in hybrid MoSe2@Au nanostructures consisting of monolayer MoSe2 supported by Au nanodisks. The optical properties of the nanostructures are probed by means of spatially resolved optical transmission and photoluminescence spectroscopies and interpreted using an analytical model complemented by numerical simulations. A plasmonic-excitonic interaction energy of 42 ± 8 meV is obtained, clearly setting the coupling in the Fano-type regime. On the basis of numerical simulations of the electromagnetic near-field and on calculations of the excitonic transition dipole momentum, we show that the interaction energy is concentrated in the gap region between the disks. The temperature dependence of the plasmonic-excitonic interaction energy is extracted from the optical transmission measurements using a Fano line shape analysis of the observed spectra. We found that the plasmonic-excitonic interaction energy is almost constant in the investigated temperature range. The plasmonic-excitonic interaction revealed in our MoSe2@Au nanohybrids is quite stable against temperature variation, which could enable potential applications on thermally driven plasmo-electronic transport or optically induced hyperthermia.

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