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Highly efficient hot electron harvesting from graphene before electron-hole thermalization
Yuzhong Chen1, Yujie Li1, Yida Zhao1
1Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China.
Science Advances
|December 11, 2019
Summary
Researchers efficiently harvested hot electrons from graphene, surpassing conventional methods by capturing energy before thermalization. This breakthrough opens new avenues for efficient solar energy harvesting devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Graphene's unique hot carrier properties offer potential for novel energy harvesting.
- Conventional methods (photothermoelectric, photothermionic) suffer low efficiencies due to hot carrier thermalization and cooling losses.
Purpose of the Study:
- To demonstrate efficient extraction of hot electrons from graphene before interband thermalization.
- To explore a new regime for hot carrier energy harvesting.
Main Methods:
- Utilized various layered semiconductors as electron-accepting components.
- Investigated hot electron injection from graphene across a broad photon energy range (visible to mid-infrared).
- Measured injection quantum yield and its dependence on excitation energy and fluence.
Main Results:
- Observed ultrafast injection of energetic hot electrons from graphene.
- Achieved injection quantum yields as high as ~50%.
- Demonstrated that yield depends on excitation energy but not fluence, unlike conventional methods.
Conclusions:
- Successfully extracted hot electrons in a previously inaccessible regime, minimizing energy and carrier loss.
- This approach closely mimics the principles of hot carrier solar cells.
- Highlights a promising pathway for advanced solar energy harvesting technologies.
