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Published on September 21st, 2013 | by Guest Contributor

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US Navy Achieves Highest Open-Circuit Voltage For Quantum Dot Solar Cells

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September 21st, 2013 by
 

Originally published on the US NRL Website.

Quantum Dot Solar Cell

Schematic of metal-lead sulfide quantum dot Schottky junction solar cells (glass/ITO/PbS QDs/LiF/Al). Novel Schottky junction solar cells developed at NRL are capable of achieving the highest open-circuit voltages ever reported for colloidal QD based solar cells.
(Photo: U.S. Naval Research Laboratory)

U.S. Naval Research Laboratory (NRL) research scientists and engineers in the Electronics Science and Technology Division have demonstrated the highest recorded open-circuit voltages for quantum dot solar cells to date. Using colloidal lead sulfide (PbS) nanocrystal quantum dot (QD) substances, researchers achieved an open-circuit voltage (VOC) of 692 millivolts (mV) using the QD bandgap of a 1.4 electron volt (eV) in QD solar cell under one-sun illumination.

“These results clearly demonstrate that there is a tremendous opportunity for improvement of open-circuit voltages greater than one volt by using smaller QDs in QD solar cells,” said Woojun Yoon, Ph.D., NRC postdoctoral researcher, NRL Solid State Devices Branch. “Solution processability coupled with the potential for multiple exciton generation processes make nanocrystal quantum dots promising candidates for third generation low-cost and high-efficiency photovoltaics.”

Despite this remarkable potential for high photocurrent generation, the achievable open-circuit voltage is fundamentally limited due to non-radiative recombination processes in QD solar cells. To overcome this boundary, NRL researchers have reengineered molecular passivation in metal-QD Schottky junction (unidirectional metal to semiconductor junction) solar cells capable of achieving the highest open-circuit voltages ever reported for colloidal QD based solar cells.

Experimental results demonstrate that by improving the passivation of the PbS QD surface through tailored annealing of QD and metal-QD interface using lithium fluoride (LiF) passivation with an optimized LiF thickness. This proves critical for reducing dark current densities by passivating localized traps in the PbS QD surface and metal-QD interface close to the junction, therefore minimizing non-radiative recombination processes in the cells.

Over the last decade, Department of Defense (DoD) analyses and the department’s recent FY12 Strategic Sustainability Performance Plan, has cited the military’s fossil fuel dependence as a strategic risk and identified renewable energy and energy efficiency investments as key mitigation measures. Research at NRL is committed to supporting the goals and mission of the DoD by providing basic and applied research toward mission-ready renewable and sustainable energy technologies that include hybrid fuels and fuel cells, photovoltaics, and carbon-neutral biological microorganisms.

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  • gitano46

    I don’t understand the confusion you people have.. it is as plain as the nose on your face… Very simply put if you have the rotor man use his rotor machine on a regular basis, when you hit the lever the crap will flow easily… got it ?

  • Peter Thomas

    I am still impressed with this fuel cell technology video that I found. Taking a human waste and creating 3 value streams of hydrogen, electricity and heat! Fantastic stuff!

    “New fuel cell sewage gas station in Orange County, CA may be world’s first”

    http://abclocal.go.com/kabc/story?section=news/local/orange_county&id=8310315

    “It is here today and it is deployable today,” said Tom Mutchler of Air Products and Chemicals Inc., a sponsor and developer of the project.

    Microsoft Backs Away From Grid

    http://blogs.wsj.com/cio/2012/11/20/microsoft-backs-away-slowly-from-the-grid/

    2.8MW fuel cell using biogas now operating; Largest PPA of its kind in North America

    http://www.fuelcelltoday.com/news-events/news-archive/2012/october/28-mw-fuel-cell-using-biogas-now-operating-largest-ppa-of-its-kind-in-north-america

    Construction of world’s largest fuel cell power plant. (in South Korea? with USA developed fuel cell technology??)

    http://www.fuelcelltoday.com/news-events/news-archive/2012/october/construction-of-worlds-largest-fuel-cell-power-plant-expected-to-commence-in-2012

  • NRG4All

    Yes, but if you take into account the the deflabulator’s effect on the disconbobulator and the subsequent downstream effect on the flatulator, it all becomes clear.

    • Steeple

      Thanks what I’m talking about

  • JamesWimberley

    ¨NRL researchers have reengineered molecular passivation in metal-QD
    Schottky junction (unidirectional metal to semiconductor junction) solar
    cells capable of achieving the highest open-circuit voltages ever
    reported for colloidal QD based solar cells.¨

    Do you think your readers can understand this or what it could bring in practical devices down the road?

    • Bob_Wallace

      Someone didn’t do their job on this one. Stuff here is supposed to be written for the general public.

      Since there’s no author listed I wonder if this got away from someone when they accidentally hit the “publish” button.

      • Cynthia Shahan

        Perhaps it is time the general public picks up this lingO?

        • JamesWimberley

          It´s a lot more than just picking up a vocabulary. The NRL blog post is plainly written for electronics engineers and semiconductor physicists with a professional interest in advanced solar cells, and provides no context for anybody else.

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