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Optical Trapping of Nanoparticles
Published on: January 15, 2013
Size-dependent trap-assisted Auger recombination in semiconductor nanocrystals
Alicia W Cohn1, Alina M Schimpf, Carolyn E Gunthardt
1Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States.
Nano Letters
|March 8, 2013
Summary
Researchers discovered accelerated trap-assisted Auger recombination in semiconductor nanocrystals. This process, dependent on nanocrystal size, impacts quantum dot technologies and solar cells.
Area of Science:
- Materials Science
- Quantum Dots
- Nanotechnology
Background:
- Auger recombination in semiconductor nanocrystals hinders applications like solar cells and quantum dot photonics.
- Previously, only multiexciton and charged-exciton Auger recombination showed significant size dependence.
Purpose of the Study:
- To report the first observation of accelerated trap-assisted Auger recombination in semiconductor nanocrystals.
- To investigate the size dependence of this recombination pathway.
Main Methods:
- Utilized time-resolved photoluminescence and transient absorption spectroscopies.
- Studied zinc oxide (ZnO) nanocrystals to probe trap-assisted Auger recombination.
Main Results:
- Observed dramatically accelerated trap-assisted Auger recombination rates with decreasing nanocrystal size.
- Recombination times decreased from >1 ns in large nanocrystals to ~80 ps in small ones.
- Demonstrated a scaling relationship of recombination rates with the inverse nanocrystal radius squared (1/τ(Auger) ~ R(-2)).
Conclusions:
- Trap-assisted Auger recombination significantly accelerates as nanocrystal size decreases.
- This recombination pathway is likely widespread in semiconductor nanocrystal photophysics due to ubiquitous surface traps.
- Findings have implications for optimizing semiconductor nanocrystal-based technologies.
