Details

Autor(en) / Beteiligte

• Pei, Huan
• Yu, Changjian
• Wei, Ting
• Qi, Jialu
• Peng, Weifeng
• Zhao, Jiaxin
• Wei, Yong

Titel

Effect of thin MoS2 film with different layer numbers on tip-enhanced photoluminescence spectroscopy

Ist Teil von

• Current applied physics, 2024-05, Vol.61, p.130-135

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• As a novel semiconductor material, Molybdenum disulfide (MoS2) has great application potential in sensors, catalysts and optoelectronic devices. In this study, we aim to investigate the unique optical properties of MoS2 by theoretically exploring the impact of thin MoS2 films with varying layer numbers on the tip-enhanced fluorescence of a single molecule confined within the nanocavity formed by an Au tip over a substrate. The influence of incidence angle, layer numbers, tip radius and tip-MoS2 film distance on the excitation field, quantum yield and fluorescence enhancement are quantitatively analyzed in detail. The results show that the presence of multilayer MoS2 film can significantly improve tip-enhanced fluorescence spectroscopy. In the strong gap-mode plasmon coupling effect, the maximum fluorescence enhancement reaches approximately five orders of magnitude when it consists of six layers under excitation wavelength of 660 nm. Furthermore, the spatial resolution of Raman and fluorescence increases with decreasing tip radius and gap distance, reaching a maximum of 2.6 nm and 3.8 nm, respectively. Our results provide a theoretical guidance for further understanding and application of the two-dimensional material in optical experiments. The comparative study of excitation field enhancement (|M|2) of tip-substrate system with (d = 2 nm) and without (d = 2 nm, 3 nm and 4 nm) monolayer MoS2 film. For electric field without MoS2 film (black line), we find two separated surface plasmonic peaks around 580 nm and 680 nm assigned to ordinary Au plasmon band and tip-substrate dipole coupling mode. At the same time, it is noticed that the peak around 680 nm covers the absorption of the MoS2 film, and thus this case can significantly enhance the excitation field when monolayer MoS2 is placed on the metallic substrate (red line), which means that the presence of MoS2 film may result in the significant Raman and fluorescence enhancement. In addition, as the increasing of the gap distance, it can be found that the peaks of field enhancement have a slight blue-shift and overall decrease due the weaker coupling. [Display omitted] •The presence of multilayer MoS2 film can significantly improve tip-enhanced fluorescence spectroscopy.•The maximum fluorescence enhancement of MoS2 with six layers reaches five orders of magnitude.•The calculated spatial resolution reach 2.6 nm and 3.8 nm for Raman and fluorescence spectroscopy.