Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Los Alamos Researchers Unravel the Mystery of Quantum Dot Blinking

"Artists conception of how solving the problem of quantum blinking
may lead to applications in areas such as solid state lighting." Courtesy Los Alamos National Laboratory
"Artists conception of how solving the problem of quantum blinking may lead to applications in areas such as solid state lighting." Courtesy Los Alamos National Laboratory

Abstract:
Research by Los Alamos scientists published today in the journal Nature documents significant progress in understanding the phenomenon of quantum-dot blinking. Their findings should enhance the ability of biologists to track single particles, enable technologists to create novel light-emitting diodes and single-photon sources, and boost efforts of energy researchers to develop new types of highly efficient solar cells.

Los Alamos Researchers Unravel the Mystery of Quantum Dot Blinking

Los Alamos, NM | Posted on November 9th, 2011

Most exciting is that the Los Alamos researchers have shown that blinking can becontrolled and even completely suppressed electrochemically. As the Nature article describes, the group developed a novel spectro-electrochemical experiment that allowed them to controllably charge and discharge a single quantum dot while monitoring its blinking behavior. These experiments facilitated the discovery of two distinct blinking mechanisms. "Our work is an important step in the development of nanostructures with stable, blinking-free properties for applications from light-emitting diodes and single-photon sources to solar cells," said Victor Klimov, LANL scientist and director of the Center for Advanced Solar Photophysics (CASP).

Quantum dots are particles between 1 and 10 nanometers in diameter. A nanometer is only one billionth of a meter across, or about 1/3000th the diameter of a human hair. At these tiny dimensions, the rules of quantum physics allow scientists to produce particles with finely tunable, size-dependent electronic and optical properties. Together with the fact that they can be fabricated by means of facile wet-chemistry techniques, their quantum nature makes these dots attractive materials for a wide range of applications.

Nanocrystal quantum dots have been on the research scene for decades. The color they produce when excited by light absorption or electrical current can be precisely tuned from the infrared through the visible to the ultraviolet spectra, andthey are cheap and easy to make.

Setagainst these advantages is a drawback—quantum-dot optical properties can randomly vary over time. Perhaps, the most dramatic manifestation of this variation is quantum-dot "blinking."

Additionally,if energized by electrical current or light, they are characterized by an effect known as Auger recombination that both competes with light emission in light-emitting diodes and reduces current output in solar cells. Both blinking and Auger recombination reduce the efficiency of quantum dots, and controlling them has been the focus of intense research.

To probe the mechanism responsible for blinking, Christophe Galland, postdoctoral researcher in CASP, along with collaborators from the Center for Integrated Nanotechnologies (CINT) and CASP developed a novel spectro-electrochemical experiment that allowed them to controllably charge and discharge a single quantum dot while monitoring its blinking behavior. It is this work that is described in the Nature article. Its main result is the discovery of two distinct blinking mechanisms.

The first is consistent with the traditional concept of quantum-dot blinking, that is, the random electrical charging and discharging of the core of the dot. In this model, a charged state is "dark" due to highly efficient nonradiative Auger recombination.

The second mechanism was a surprise; the majority of quantum dots blink due to the filling and emptying of a surface defect "trap" on the dot. If not occupied, this trap intercepts a "hot" electron that would otherwise produce photon emission, thus causing a blink. With further research into the photophysical properties of quantum dots, the scientists hope to provide a comprehensive theoretical model of this phenomenon.

"The new single nanocrystal spectro-electrochemistry technique developed here could readily be extended to study the effect of charging in a wide array of nanostructures, including carbon nanotubes and nanowires," said Han Htoon, a CINT staff scientist who took part in the research. "I believe that it will become an important new capability for CINT."

Experiments were conducted at CINT, a U.S. Department of Energy Office of Science User Facility and Nanoscale Science Research Center. Its emphasis is on exploring the path from scientific discovery to the integration of nanostructures into the micro and macro worlds.

CASP is an Energy Frontier Research Center funded by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences. Its goal is to explore the unique physics of nanoscale materials to boost the efficiency of solar energy conversion through novel light-matter interaction regimes, controlled excited-state dynamics, and engineered carrier-carrier coupling.

This work was also sponsored by the National Institutes of Health, NIH-NIGMS grant 1R01GM084702-01 (Htoon, Sykora, Hollingsworth, P.I.) that has the core aim of developing novel non-blinking quantum dots as molecular probes. This work was also sponsored by the Los Alamos National Laboratory Directed Research and Development (LDRD) program.

Reference: "Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots." Nature, November 10, 2011. doi:10.1038/nature10569. Christophe Galland, Yagnaseni Ghosh, Andrea Steinbruck, Milan Sykora, Jennifer A. Hollingsworth, Victor I. Klimov & Han Htoon. Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

####

About Los Alamos National Laboratory
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los AlamosNational Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and URS for the Department of Energy’s National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

For more information, please click here

Contacts:
Nancy Ambrosiano
505.667.0471

Copyright © Los Alamos National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Nanoscale assembly line August 29th, 2014

New analytical technology reveals 'nanomechanical' surface traits August 29th, 2014

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

Display technology/LEDs/SS Lighting/OLEDs

Copper shines as flexible conductor August 29th, 2014

Laboratories

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

X-ray Laser Probes Tiny Quantum Tornadoes in Superfluid Droplets: SLAC Experiment Reveals Mysterious Order in Liquid Helium August 25th, 2014

Shaping the Future of Nanocrystals: Berkeley Lab Researchers Obtain First Direct Observation of Facet Formation in Nanocubes August 21st, 2014

Govt.-Legislation/Regulation/Funding/Policy

New analytical technology reveals 'nanomechanical' surface traits August 29th, 2014

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

Leading European communications companies and research organizations have launched an EU project developing the future 5th Generation cellular mobile networks August 28th, 2014

New technique uses fraction of measurements to efficiently find quantum wave functions August 28th, 2014

Discoveries

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Nanoscale assembly line August 29th, 2014

Copper shines as flexible conductor August 29th, 2014

Novel 'butterfly' molecule could build new sensors, photoenergy conversion devices August 28th, 2014

Announcements

A new, tunable device for spintronics: An international team of scientists including physicist Jairo Sinova from the University of Mainz realises a tunable spin-charge converter made of GaAs August 29th, 2014

Nanoscale assembly line August 29th, 2014

New analytical technology reveals 'nanomechanical' surface traits August 29th, 2014

New Vice President Takes Helm at CNSE CMOST: Catherine Gilbert To Lead CNSE Children’s Museum of Science and Technology Through Expansion And Relocation August 29th, 2014

Energy

Novel 'butterfly' molecule could build new sensors, photoenergy conversion devices August 28th, 2014

Aspen Aerogels, Inc. to Present at Barclays CEO Energy-Power Conference August 27th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Chemical reaction yields "tapes" of porphin molecules: Flexible tapes from the nanoworld August 13th, 2014

Quantum Dots/Rods

Interaction between Drug, DNA for Designing Anticancer Drugs Studied in Iran August 17th, 2014

NANOPARTICLES INDIA August 8th, 2014

Researchers create quantum dots with single-atom precision June 30th, 2014

New Los Alamos Approach May Be Key to Quantum Dot Solar Cells With Real Gains in Efficiency: Nanoengineering Boosts Carrier Multiplication in Quantum Dots June 19th, 2014

Solar/Photovoltaic

Novel 'butterfly' molecule could build new sensors, photoenergy conversion devices August 28th, 2014

Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014

Eco-friendly 'pre-fab nanoparticles' could revolutionize nano manufacturing: UMass Amherst team invents a way to create versatile, water-soluble nano-modules August 13th, 2014

An Inkjet-Printed Field-Effect Transistor for Label-Free Biosensing August 11th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE