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Published on: October 13, 2017
Dynamics of Intermittent Delayed Emission in Single CdSe/CdS Quantum Dots
Stijn O M Hinterding1,2, Sander J W Vonk1,2, Elleke J van Harten1
1Soft Condensed Matter, Utrecht University, Princetonplein 1, 3584CC Utrecht, The Netherlands.
Semiconductor nanocrystals, or quantum dots (QDs), exhibit slow "delayed emission" that fluctuates, offering potential for control. This phenomenon correlates with red-shifted spectra, suggesting surface charge dynamics influence QD fluorescence.
Area of Science:
- Materials Science
- Nanotechnology
- Spectroscopy
Background:
- Semiconductor nanocrystals (quantum dots, QDs) offer bright, fast fluorescence for diverse applications.
- A small fraction of QD fluorescence exhibits slow, delayed emission, a poorly understood phenomenon.
- This delayed emission can negatively impact applications or present new opportunities.
Purpose of the Study:
- To characterize the dynamics of delayed emission in individual CdSe/CdS core/shell QDs.
- To correlate delayed emission characteristics with spectral changes.
- To understand the underlying mechanisms influencing QD fluorescence behavior.
Main Methods:
- Single-particle spectroscopy of individual CdSe/CdS core/shell quantum dots.
- Time-resolved fluorescence intensity measurements.
- Spectral analysis of QD emission during delayed emission events.
Main Results:
- Delayed emission intensity from single QDs fluctuates significantly over time.
- Periods of bright delayed emission are associated with red-shifted emission spectra.
- Observed behavior aligns with exciton polarization models driven by surface charge dynamics.
Conclusions:
- Delayed emission in QDs is dynamic and potentially controllable.
- Surface charge diffusion and electric field fluctuations play a key role in QD spectral diffusion and delayed emission.
- Findings provide a basis for future research into controlling QD delayed emission.
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