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Hot carrier diffusion-assisted ideal carrier multiplication in monolayer MoSe2
Joonsoo Kim1, Hong-Guk Min2, Sehwan Park1
1Department of Energy Science, Sungkyunkwan University, South Korea.
Materials Horizons
|April 16, 2025
Summary
Monolayer MoSe2 achieves ideal carrier multiplication (CM) efficiency by minimizing energy loss and enabling multiple charge carriers per photon. This breakthrough in 2D materials offers a path beyond the Shockley-Queisser limit for photovoltaics.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Optoelectronics
Background:
- Carrier multiplication (CM) generates multiple charge carriers from one photon, potentially surpassing the Shockley-Queisser limit in solar cells.
- Existing materials struggle with ideal CM efficiency due to energy losses from carrier-lattice scattering.
Purpose of the Study:
- To demonstrate ideal carrier multiplication efficiency in monolayer MoSe2.
- To identify the mechanisms enabling optimal CM in this 2D material.
Main Methods:
- Ultrafast transient absorption spectroscopy to observe hot carrier dynamics.
- First-principles calculations to validate experimental findings.
- Comparative analysis between monolayer and bulk MoSe2.
Main Results:
- Monolayer MoSe2 achieves theoretical maximum CM efficiency.
- Scatter-free ballistic transport of hot carriers was observed.
- Suppressed energy dissipation via minimized carrier-lattice scattering and abundant CM pathways were identified as key factors.
- Enhanced CM efficiency in monolayer MoSe2 compared to bulk MoSe2.
Conclusions:
- Monolayer MoSe2 exhibits superior hot-carrier dynamics, enabling optimal CM.
- This 2D material is a promising candidate for high-performance optoelectronics and next-generation energy conversion.
