Charge Carrier Dynamics in Colloidally Synthesized Monolayer MoX2 Nanosheets
Chandra Sekhar M1,2, Gabriele Pippia1,3, Ivo Tanghe2,4
1Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, 9000 Ghent, Belgium.
The Journal of Physical Chemistry Letters
|March 8, 2023
Summary
Charge carrier dynamics in monolayer colloidal transition metal dichalcogenides (c-TMDs) are dominated by fast electron trapping, unlike their multilayered counterparts. This finding aids in optimizing c-TMDs for optoelectronics and photocatalysis.
Area of Science:
- Materials Science
- Nanotechnology
- Semiconductor Physics
Background:
- Colloidal transition metal dichalcogenides (c-TMDs) are promising nanostructured semiconductors.
- Recent advances allow synthesis of monolayer c-TMDs, but their charge carrier dynamics remain unclear.
Purpose of the Study:
- To elucidate the charge carrier dynamics in monolayer c-TMDs.
- To compare these dynamics with multilayered c-TMDs.
- To identify mechanisms influencing exciton shifts.
Main Methods:
- Broadband and multiresonant pump-probe spectroscopy.
- Detailed hyperspectral fitting procedures.
Main Results:
- Monolayer c-TMDs exhibit fast electron trapping, distinct from hole-dominated trapping in multilayered counterparts.
- Exciton red shifts are observed and attributed to trapped electrons and lattice heating.
- This electron-trapping mechanism is consistent across MoS2 and MoSe2.
Conclusions:
- Charge carrier dynamics in monolayer c-TMDs are primarily governed by electron trapping.
- Understanding these dynamics is crucial for optimizing c-TMDs for applications.
- Passivation of electron-trap sites offers a route for improved material performance.
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