Dynamic Fluctuations in Ultrasmall Nanocrystals Induce White Light Emission

Individual ultrasmall CdSe nanocrystals have recently been found to emit white light, but the ultimate origin of the phenomenon has remained elusive. Here we use a combination of state-of-the-art experiment and theory to show that excitation sets the ultrasmall nanocrystals into a fluxional state. T...

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Bibliographic Details
Published in:Nano letters 2012-06, Vol.12 (6), p.3038-3042
Main Authors: Pennycook, Timothy J, McBride, James R, Rosenthal, Sandra J, Pennycook, Stephen J, Pantelides, Sokrates T
Format: Article
Language:English
Subjects:
Cadmium Compounds - chemistry
Color
Cross-disciplinary physics: materials science
rheology
Emission
Emittance
Energy gap
Exact sciences and technology
Femtosecond
Fluctuation
Lighting - methods
Materials science
Materials Testing
Nanocrystalline materials
Nanocrystals
Nanoscale materials and structures: fabrication and characterization
Nanostructures - chemistry
Nanostructures - ultrastructure
Optimization
Particle Size
Physics
Selenium Compounds - chemistry
Visual
White light
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Summary:Individual ultrasmall CdSe nanocrystals have recently been found to emit white light, but the ultimate origin of the phenomenon has remained elusive. Here we use a combination of state-of-the-art experiment and theory to show that excitation sets the ultrasmall nanocrystals into a fluxional state. Their energy gaps vary continuously on a femtosecond time scale, so that even an individual nanocrystal can emit across the entire visual range. In addition, we observe the outer layers of the larger monochromatic emitting nanocrystals to be fluxional. Such fluxionality should be considered when optimizing nanocrystals for applications. Thus, small is indeed different, but ultrasmall is different yet again.
ISSN:1530-6984
1530-6992
DOI:10.1021/nl3008727