Localized exciton emission from monolayer WS₂ nanoribbon at cryogenic temperature

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Transition metal dichalcogenides (TMDCS) like WS₂ and MoSe₂ exhibit unique electronic and optical properties.
• Nanostructured TMDCS are promising for advanced electronic and optoelectronic devices.

Purpose of the Study:

• To investigate the optical properties of individual WS₂ and MoSe₂ nanoribbons.
• To understand the nature of excitonic emissions in these nanostructures.
• To explore the potential applications of TMDCS nanoribbons in sensing and optoelectronics.

Main Methods:

• Low-temperature photoluminescence (PL) spectroscopy.
• Gold-assisted exfoliation of WS₂ and MoSe₂ nanoribbons from vicinal crystal surfaces.
• Analysis of spectral diffusion, pump power, and temperature dependence.

Main Results:

• Monolayer WS₂ and MoSe₂ nanoribbons with widths from tens to hundreds of nanometers were successfully prepared.
• MoSe₂ nanoribbons exhibited emission profiles similar to 2D excitons.
• WS₂ nanoribbons displayed sharp peaks attributed to localized excitons/trions and a broad peak from bilayer regions.

Conclusions:

• The optical properties of WS₂ and MoSe₂ nanoribbons differ, with WS₂ showing localized exciton behavior.
• Localized exciton emission in WS₂ nanoribbons is sensitive to environmental factors.
• TMDCS nanoribbons hold significant promise for future sensing and optoelectronic applications.