Inverted Chiral Response in Folded Anisotropic van der Waals Materials

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• In-plane anisotropic van der Waals (vdW) materials exhibit chirality-related properties tied to their vertical orientations.
• Achieving controlled vertical orientations in these materials is a significant challenge.
• This limits their potential in novel optoelectronic applications.

Purpose of the Study:

• To introduce a facile one-step folding approach for creating structural differences in anisotropic vdW materials.
• To demonstrate the feasibility of this method using rhenium disulfide (ReS2).
• To explore the resulting chirality-dependent phenomena for optoelectronic applications.

Main Methods:

• Electrochemical exfoliation of rhenium disulfide (ReS2).
• One-step folding during the drop-casting process to induce structural differences.
• Characterization using atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), polarized optical microscopy, angle-resolved photoluminescence, and Raman spectroscopy.

Main Results:

• The folding method successfully created distinct vertical orientations in ReS2 flakes.
• While structural and electronic properties remained similar, optical characterizations revealed significant chiral phenomena.
• Opposite vertical orientations were confirmed in folded ReS2 regions.
• Chirality-dependent Raman spectra and photocurrent were observed.

Conclusions:

• The proposed folding technique offers a viable strategy for engineering vertical orientations in anisotropic vdW materials.
• The observed chirality-dependent optical and electronic responses open avenues for chirality-related optoelectronic devices.
• This work highlights the potential of manipulating vdW material structures for advanced functionalities.