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-- WITH PHOTO -- TO ENERGY, AND NATIONAL EDITORS:
Shiny Quantum Dots Brighten Future of Solar Cells
LOS ALAMOS, N.M., April 14, 2014 /PRNewswire-USNewswire/ -- A house
window that doubles as a solar panel could be on the horizon, thanks
to recent quantum-dot work by Los Alamos National Laboratory
researchers in collaboration with scientists from University of
Milano-Bicocca (UNIMIB), Italy. Their project demonstrates that
superior light-emitting properties of quantum dots can be applied in
solar energy by helping more efficiently harvest sunlight.
"The key accomplishment is the demonstration of large-area luminescent
solar concentrators that use a new generation of specially engineered
quantum dots," said lead researcher Victor Klimov of the Center for
Advanced Solar Photophysics (CASP) at Los Alamos.
Quantum dots are ultra-small bits of semiconductor matter that can be
synthesized with nearly atomic precision via modern methods of
colloidal chemistry.
A luminescent solar concentrator (LSC) is a photon management device,
representing a slab of transparent material thatcontainshighly
efficient emitters such as dye molecules or quantum dots. Sunlight
absorbed in the slab is re-radiated at longer wavelengths and guided
towards the slab edge equipped with a solar cell.
Klimov explained, "The LSC serves as a light-harvesting antenna which
concentrates solar radiation collected from a large area onto a much
smaller solar cell, and this increases its power output."
"LSCs are especially attractive because in addition to gains in
efficiency, they can enable new interesting concepts such as
photovoltaic windows that can transform house facades into large-area
energy generation units," said Sergio Brovelli, a faculty member at
UNIMIB.
Because of highly efficient, color-tunable emission and solution
processability, quantum dots are attractive materials for use in
inexpensive, large-area LSCs. To overcome a nagging problem of light
reabsorption, the Los Alamos and UNIMIB researchers developed LSCs
based on quantum dots with artificially induced large separation
between emission and absorption bands (called a large Stokes shift).
These "Stokes-shift" engineered quantum dots represent cadmium
selenide/cadmium sulfide (CdSe/CdS) structures in which light
absorption is dominated by an ultra-thick outer shell of CdS, while
emission occurs from the inner core of a narrower-gap CdSe.
Los Alamos researchers created a series of thick-shell (so-called
"giant") CdSe/CdS quantum dots, which were incorporated by their
Italian partners into large slabs (sized in tens of centimeters) of
polymethylmethacrylate (PMMA). While being large by quantum dot
standards, the active particles are still tiny - only about hundred
angstroms across. For comparison, a human hair is about 500,000
angstroms wide.
A journal article is in Nature Photonics at
http://dx.doi.org/10.1038/NPHOTON.2014.54
About Los Alamos National Laboratory ( www.lanl.gov ) Los Alamos
National Laboratory, a multidisciplinary research institution engaged
in strategic science on behalf of national security, is operated by
Los Alamos National Security, LLC, a team composed of Bechtel
National, the University of California, The Babcock & Wilcox Company
and URS Corporation 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.
Photo - http://photos.prnewswire.com/prnh/20140414/73007
SOURCE Los Alamos National Laboratory
-0- 04/14/2014
/CONTACT: Nancy Ambrosiano, 505.667.0471, nwa@lanl.gov
/Photo: http://photos.prnewswire.com/prnh/20140414/73007
PRN Photo Desk, photodesk@prnewswire.com
CO: Los Alamos National Laboratory
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