NREL Certifies First All-Quantum-Dot Photovoltaic Cell; Demonstrates Stability, Performance (Fact Sheet) Page: 1 of 1
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NREL Certifies First
Cell; Demonstrates Stability,
Work demonstrates that smaller can be better: quantum
confinement can lead to increased PV efficiency and could
lead to a doubling of third-generation solar cell efficiencies.
Tiny quantum dots just a few nanometers in diameter can do great things when it
comes to generating electricity, or perhaps even solar fuels.
Researchers at the National Renewable Energy Laboratory (NREL) have certified the first
all-quantum-dot photovoltaic cell, which was based on lead sulfide and demonstrated
reasonable quantum dot solar cell performance for an initial efficiency measurement
along with good stability. The certified open-circuit voltage of the quantum dot cell is
greater than that possible from bulk lead sulfide because of quantum confinement.
These results increase the motivation to explore quantum dots for their capacity to
deliver multiple electrons from each photon, a phenomenon that if applied to solar
cells could greatly improve even double their efficiency.
Quantum dots have such great photon-to-electricity potential because when a single
photon of light of sufficient energy is absorbed by a quantum dot, it produces more
than one bound electron-hole pair, or exciton. The process is called multiple exciton
generation, and it was first predicted by NREL researchers. In conventional PV cells with
much larger crystals and many more atoms, one photon produces only one electron-
The key to the greater multiplication efficiency in quantum dots is that the electron-
hole pair is in a confined space the physical boundaries of the quantum dot. There-
fore, they interact strongly and increase the probability of generating multiple excitons.
NREL scientists grow quantum dots via inexpensive colloidal chemistry. Quantum
dots are formed when a metal ion chemically reacts with a molecule that donates a
References: Stability Assessment on a 3% Bi ayer PbS/ZnO Quantum Dot Heterojunction Solar Cell Advanced
Materials DOI 101002/adma 201001148 Published onlineJune 8, 2010
Comparing Multiple Exciton Generation in Quantum Dots to Impact Ionization in Bulk Semiconductors Implications
for Enhancement of solar Energy Conversion, Nano Letters, v10, pp 3019, 2010
1 5 eV b CD Gold back contct
70 n1 Chick
5 rim Zno NCs
Key Research Results
NREL scientists were the first to certify
the stability and performance of an
all-quantum-dot device, demonstrating
that confining electrons and holes to the
tiny space of a quantum dot can lead to
increased PV efficiency in solar cells.
The success opens the door to more
directed research into the potential
benefits of quantum dots and their
capacity to generate two electrons from a
single absorbed photon in a solar cell.
bonus exhibited by a stable quantum dot
device could lead to a dramatic increase in
the conversion efficiency into electricity in
NATIONAL RENEWABLE ENERGY LABORATORY
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NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable
Energy, operated by the Alliance for Sustainable Energy, LLC.
NREL/FS-5900-50855 - February 2011
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NREL Certifies First All-Quantum-Dot Photovoltaic Cell; Demonstrates Stability, Performance (Fact Sheet), report, February 1, 2011; Golden, Colorado. (digital.library.unt.edu/ark:/67531/metadc832999/m1/1/: accessed October 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.