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Matthew Pelton of Argonne�s Center for Nanoscale
Materials adjusts a green laser used to monitor the sporadic
blinking of quantum dots.
Photo � by Argonne National Laboratory.
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Quantum dots have great promise as
light-emitting materials, because the wavelength, or color, of light
that the quantum dots give off can be very widely tuned simply by
changing the size of the nanoparticles. If a single dot is observed
under a microscope, it can be seen to randomly switch between bright
and dark states. This flickering, or blinking, behavior has been
widely studied, and it has been found that a single dot can blink off
for times that can vary between microseconds and several minutes. The
causes of the blinking, though, remain the subject of intense study.
The methods developed by Matt Pelton of Argonne's Center for Nanoscale
Materials and his team of collaborators has revealed a previously
unobserved change in the blinking behavior on time scales less than a
few microseconds. This observation is consistent with the predictions
of a model for quantum-dot blinking previously developed by Nobel
Laureate Rudolph Marcus, contributor to this research, and his
co-workers. In this model, the blinking is controlled by the random
fluctuation of energy levels in the quantum dot relative to the
energies of trap states on the surface of the nanocrystal or in the
nearby environment.
The results of this research provide new insight into the mechanism of
quantum-dot blinking, and should help in the development of methods to
control and suppress blinking. Detailed results of this work have been
published in a paper in the Proceedings of the National Academy of
Sciences.
Argonne's Center for Nanoscale Materials work for this research was
funded by the U.S. Department of Energy's Office of Basic Energy
Science.
Argonne National Laboratory, a renowned R&D center, brings the world's
brightest scientists and engineers together to find exciting and
creative new solutions to pressing national problems in science and
technology. The nation's first national laboratory, Argonne conducts
leading-edge basic and applied scientific research in virtually every
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researchers from hundreds of companies, universities, and federal,
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problems, advance America 's scientific leadership and prepare the
nation for a better future. With employees from more than 60 nations,
Argonne is managed by UChicago Argonne, LLC for the U.S. Department of
Energy's Office of Science.
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