Spatiotemporal Cooling and Diffusion of Hot Interlayer Excitons in Moiré-Potential-Suppressed WSe2/WS2
Xiaofan Wei1, Chengjiang Du1, Le Kang1
1School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.
ACS Nano
|December 11, 2025
Summary
Hot interlayer excitons (HIEs) in 2D vdW heterostructures show linear diffusion in suppressed moiré potentials. Their extended cooling time suggests potential for efficient hot-carrier optoelectronics.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Optoelectronics
Background:
- Hot interlayer excitons (HIEs) in 2D van der Waals (vdW) heterostructures are key for exceeding the Shockley-Queisser limit in hot-carrier optoelectronics.
- Understanding HIE spatiotemporal dynamics and cooling in transition metal dichalcogenide (TMD) bilayers is crucial, as moiré potentials heavily influence interlayer exciton transport.
Purpose of the Study:
- Investigate HIE spatiotemporal diffusion and cooling behavior in WSe2/WS2 bilayer heterostructures.
- Explore the impact of suppressed moiré potentials (twist angle ~36°) on interlayer exciton dynamics.
- Provide experimental evidence for HIE spatial diffusion in TMD bilayers.
Main Methods:
- Fabrication and characterization of WSe2/WS2 bilayer heterostructures with a ~36° twist angle.
- Optical spectroscopy techniques to probe exciton dynamics under above-bandgap excitation.
- Analysis of spatiotemporal diffusion and cooling behavior of HIEs.
Main Results:
- Observed linear spatiotemporal diffusion of interlayer excitons in weak moiré potential conditions, contrasting with nonlinear dynamics in strong moiré potentials.
- Direct experimental observation of HIE spatial diffusion in TMD bilayer heterostructures.
- Demonstrated that HIE cooling time is significantly longer (order of magnitude) than intralayer excitons in monolayer TMDs.
Conclusions:
- Suppressed moiré potentials enable distinct linear diffusion dynamics for interlayer excitons.
- HIEs exhibit spatial diffusion and extended lifetimes in engineered TMD heterostructures.
- Findings support the potential of HIEs in 2D heterostructures for advanced optoelectronic and energy-harvesting applications.
Keywords:
hot interlayer excitonsspatiotemporal cooling and diffusiontransient absorptiontransient absorption microscopytransition metal dichalcogenides bilayer heterostructuresMore Related Videos
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