Plasmon damping and charge transfer pathways in Au@MoSe2 nanostructures

Abstract

Hybridization of plasmonic and excitonic elementary excitations provides an efficient mean of enhancing the optical absorption and emission properties of metal/semiconductor nanostructures and is a key concept for the design of novel efficient optoelectronic devices.Here we investigate the optical properties of 2D MoSe 2 quantum well flakes covered with Au nanoparticles supporting plasmonic resonances. Using spatially resolved confocal spectroscopy, we report the observation of a quenching phenomenon of the Raman scattering and photoluminescence emission of both the MoSe 2 layer and the Au nanoparticles. We found that the quenching of the photoluminescence emission from the Au nanoparticles is partial and measurable unlike the one observed for the Au-covered MoSe 2 layers, which is total. Its dependence on the thickness of the MoSe 2 layer is determined experimentally. Based on electro-dynamics calculations and on the electronic band alignment at the Au/ MoSe 2 interface, the results are interpreted in terms of i) damping of the plasmonic resonance of the Au nanoparticles due to the optical absorption by the MoSe 2 layer ii) a two-pathways charge transfer scheme where the photo-excited electrons leak from the MoSe 2 layer to the Au NPs whereas the photo-excited holes flow in the opposite direction i.e., from the Au NPs to the MoSe 2 layer. The two combined mechanisms account well for the experimental observations and complements the interpretations proposed in the literature for similar metal nanoparticles/transition metal dichalcogenide systems.

Insights into the Semiconductor SERS Activity: The Impact of the Defect-Induced Energy Band Offset and Electron Lifetime Change

“…The broad absorption band also indicates that defect states are distributed across a significant portion of the band gap. Moreover, it can be observed that the plasmon resonance of H x MoO 3 is relatively weak, although it is highly defective, implying that the hot electron recombination rate in H x MoO 3 is extremely fast. , …”

“…Moreover, it can be observed that the plasmon resonance of H x MoO 3 is relatively weak, although it is highly defective, implying that the hot electron recombination rate in H x MoO 3 is extremely fast. 40,41 SERS Performance Evaluation. The oxygen vacancy defect density in MoO 3 and H x MoO 3 was tuned using a 365 nm UV light (see the Tuning Oxygen Vacancy by UV Light Section in Supporting Information and Figure S1).…”

A Review of Transition Metal Dichalcogenides-Based Biosensors

“…For example, AuNPs are assembled on the surface of TMDCs through the gold sulfhydryl bond (Au-S bonds) ( Kong et al, 2020 ) generated between the coordinated structure of MoS 2 and AuNPs ( Parlak et al, 2017 ). Recent studies have proved that the deposition of metal nanoparticles on TMDCs may change the electronic, optical, and vibrational properties of the TMDCs layer ( Abid et al, 2021 ). Zhang et al (2016) demonstrated the strain effect induced by metal nanoparticles deposited on the MoS 2 layer using surface-enhanced Raman scattering (SERS).…”

On the unique temperature-dependent interplay of a B-exciton and its trion in monolayer MoSe2

“…The increasing demand of novel electronic and optoelectronic applications has motivated deeper explorations of low dimensional materials, 1 nanoparticles, 2,3 and their interfaces. 2,4 In the two-dimensional materials family, 5 monolayer transition metal dichalcogenides (TMDs) have found a special place due to their direct band gap in the visible range, chemical stability, and reasonable charge mobilities. 5 Recent progress in nanoparticle preparation techniques 6 has enabled TMD heterojunctions with metallic and semiconducting nanoparticles aiding physicists, chemists, biologists, and materials scientists to explore the intimate interaction of nanostructures with monolayer semiconductors.…”