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Twist Angle-Dependent Exciton Mobility in WS2 Bilayers
Yangguang Zhong1,2, Shuai Yue2,3, Jieyuan Liang1,4
1Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometriscs and College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082, China.
Nano Letters
|March 4, 2025
Summary
Twist angle significantly impacts exciton transport in bilayer tungsten disulfide (WS2). Stronger interlayer coupling enhances exciton mobility, crucial for developing advanced excitonic devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Bilayer tungsten disulfide (WS2) is promising for excitonic devices due to its unique properties.
- Understanding twist angle effects on exciton transport is limited.
Purpose of the Study:
- To systematically investigate exciton mobility in bilayer WS2 with varying twist angles.
- To elucidate the roles of interlayer coupling and moiré potential in exciton transport.
Main Methods:
- Transient reflection microscopy (TRM) was used to study exciton mobility.
- Chemical vapor deposition (CVD) grown bilayer WS2 with controlled twist angles was employed.
Main Results:
- Exciton mobility was highest (87.3 cm2/V s) at 0° twist angle, with a 1.06 μm diffusion length.
- Mobility decreased to 44.5 cm2/(V s) at 25° twist due to weakened coupling and moiré effects.
- 60° twist angle showed intermediate exciton transport characteristics.
Conclusions:
- Interlayer coupling and moiré potential critically influence exciton transport dynamics.
- Findings provide guidelines for engineering excitonic devices based on 2D semiconductors.
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