Exchange between Interlayer and Intralayer Exciton in WSe₂/WS₂ Heterostructure by Interlayer Coupling Engineering

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Interlayer excitons (IXs) are crucial for excitonic devices in van der Waals (vdW) heterostructures.
• Controlling IX behavior is key for advancing excitonic integrated devices.

Purpose of the Study:

• To investigate the effects of high pressure and tensile strain on interlayer coupling in WSe₂/WS₂ heterostructures.
• To demonstrate the manipulation of intralayer and interlayer excitons through mechanical strain.

Main Methods:

• First-principles calculations were employed to analyze band structures and interlayer distances.
• Simulations explored the impact of high pressure and uniaxial tensile strain on WSe₂/WS₂ heterostructures.

Main Results:

• High pressure enhances interlayer coupling, converting intralayer excitons to IXs and reducing interlayer distance.
• Tensile strain reduces interlayer coupling, transforming IXs back to intralayer excitons and increasing interlayer distance.
• A direct-to-indirect band gap transition was observed in the WSe₂/WS₂ heterostructure under these conditions.

Conclusions:

• The study successfully demonstrated the reversible transformation between interlayer and intralayer excitons in WSe₂/WS₂ heterostructures.
• Mechanical control of excitons via pressure and strain opens new avenues for designing advanced excitonic devices.