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Biexciton auger recombination in colloidal graphene quantum dots
Cheng Sun1, Florian Figge1, John A McGuire1
1Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA.
Physical Review Letters
|September 20, 2014
Summary
Colloidal graphene quantum dots exhibit biexciton Auger recombination (AR) similar to carbon nanotubes. This finding in sp2-hybridized carbon nanostructures suggests potential for carrier multiplication applications.
Area of Science:
- Materials Science
- Quantum Dots
- Nanotechnology
Background:
- Auger recombination (AR) is a critical process affecting exciton dynamics in nanomaterials.
- Understanding AR in graphene quantum dots (GQDs) is essential for their optoelectronic applications.
Purpose of the Study:
- To measure biexciton Auger recombination (AR) in colloidal graphene quantum dots (GQDs).
- To compare AR rates in GQDs with other carbon nanostructures like carbon nanotubes.
Main Methods:
- Transient absorption spectroscopy was employed to study biexciton dynamics.
- Graphene quantum dots with 132 and 168 sp2-hybridized carbon atoms were investigated.
Main Results:
- Biexciton AR was observed in GQDs with a time constant of approximately 0.3 picoseconds.
- The AR amplitude showed a superlinear dependence on pump fluence.
- Similar biexciton AR rates were found in GQDs and carbon nanotubes, despite size differences.
Conclusions:
- Strong carrier interactions in sp2-hybridized carbon nanostructures contribute to similar AR rates.
- Colloidal graphene quantum dots show promise for applications involving carrier multiplication.
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