Transient Absorption Measurements on Anisotropic Monolayer ReS2.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Two-dimensional (2D) transition metal dichalcogenides (TMDs) are materials with unique electronic and optical properties.
• Understanding the anisotropic behavior of 2D materials is crucial for developing next-generation electronic and optoelectronic devices.
• Monolayer ReS2, a less-studied TMD, is synthesized via mechanical exfoliation.

Purpose of the Study:

• To investigate the anisotropic optical and transport properties of monolayer ReS2.
• To determine the relationship between light polarization, sample orientation, and optical response.
• To quantify exciton dynamics, including diffusion and lifetime, in relation to crystal structure.

Main Methods:

• Fabrication of monolayer ReS2 using mechanical exfoliation.
• Transient absorption spectroscopy with controlled polarization configurations and sample orientations.
• Spatiotemporal dynamics analysis of excitons.

Main Results:

• Monolayer ReS2 displays anisotropic absorption coefficients and transient absorption, with peak values along the Re atomic chain direction.
• Exciton diffusion coefficient is approximately 16 cm(2) s(-1) along the Re chains, three times higher than perpendicular to them.
• An exciton lifetime of 40 picoseconds (ps) was determined.

Conclusions:

• Monolayer ReS2 exhibits significant optical and charge transport anisotropy.
• The orientation of Re atomic chains dictates the material's anisotropic characteristics.
• Monolayer ReS2 is confirmed as an anisotropic 2D transition metal dichalcogenide with potential applications in anisotropic devices.