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Discovery Could Sharply Boost Solar Cell Efficiency at Low Cost

By Joe Romm

"Discovery Could Sharply Boost Solar Cell Efficiency at Low Cost"


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Chart from Emanuel Sachs of MIT with data that is already two years old.  Recent discoveries hold the promise of keeping the cost reductions going past 2020.

New research on solar energy conversion finds, “the efficiency of conventional solar cells could be significantly increased.”  The research was led by chemist Xiaoyang Zhu at The University of Texas at Austin.  Their news release explains:

it’s possible to double the number of electrons harvested from one photon of sunlight using an organic plastic semiconductor material.

Plastic semiconductor solar cell production has great advantages, one of which is low cost,” said Zhu, a professor of chemistry. “Combined with the vast capabilities for molecular design and synthesis, our discovery opens the door to an exciting new approach for solar energy conversion, leading to much higher efficiencies.”

The research holds the possibility of increasing the efficiency of solar cells by 50% to 100%.

A recent study found that “Solar Power Is Much Cheaper to Produce Than Most Analysts Realize.”  And Climate Progress has laid out a path for further reductions (see Anatomy of a Solar PV System: How to Continue “Ferocious Cost Reductions” for Solar Electricity).

Advances like this one hold the promise of even further reductions post-2020.  The study itself in Science, “Observing the Multiexciton State in Singlet Fission and Ensuing Ultrafast Multielectron Transfer” (subs. req’d) is pretty technical stuff.

Here’s a more digestible version of the finding from the news release:

The maximum theoretical efficiency of the silicon solar cell in use today is approximately 31 percent, because much of the sun’s energy hitting the cell is too high to be turned into usable electricity. That energy, in the form of “hot electrons,” is instead lost as heat. Capturing hot electrons could potentially increase the efficiency of solar-to-electric power conversion to as high as 66 percent.

Zhu and his team previously demonstrated that those hot electrons could be captured using semiconductor nanocrystals. They published that research in Science in 2010, but Zhu says the actual implementation of a viable technology based on that research is very challenging.

“For one thing,” said Zhu, “that 66 percent efficiency can only be achieved when highly focused sunlight is used, not just the raw sunlight that typically hits a solar panel. This creates problems when considering engineering a new material or device.”

To circumvent that problem, Zhu and his team have found an alternative. They discovered that a photon produces a dark quantum “shadow state” from which two electrons can then be efficiently captured to generate more energy in the semiconductor pentacene.

Zhu said that exploiting that mechanism could increase solar cell efficiency to 44 percent without the need for focusing a solar beam, which would encourage more widespread use of solar technology.

And here’s the basics of the underlying science:

  • Absorption of a photon in a pentacene semiconductor creates an excited electron-hole pair called an exciton.
  • The exciton is coupled quantum mechanically to a dark “shadow state” called a multiexciton.
  • This dark shadow state can be the most efficient source of two electrons via transfer to an electron acceptor material, such as fullerene, which was used in the study.
  • Exploiting the dark shadow state to produce double the electrons could increase solar cell efficiency to 44 percent.

One never knows which advances will ultimately succeed in the marketplace, and new research typically takes many years to be commercialized.  But the trend toward a steady reduction in cost is poised to continue for a long, long time.

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16 Responses to Discovery Could Sharply Boost Solar Cell Efficiency at Low Cost

  1. Mulga Mumblebrain says:

    Excellent news! Imagine the advances that could be made if the money wasted on fossil fuel subsidies, nuclear energy promotion or the apparatus of murder and intimidation euphemised as ‘defence’ spending, was put to work to avert ecological and resource depletion disaster. That it is not, that, in fact, in Austr-failure and elsewhere, Rightwing pathocracies are fiercely attacking renewables and pushing, with real zealotry, coal and gas instead, convinces me that the kakistocrats want the climate disaster to happen. No other explanation any longer makes sense.

    • Interesting Times says:

      …the kakistocrats want the climate disaster to happen. No other explanation any longer makes sense.

      How about, the kakistocrats are a bunch of old fossils (ha) who think that, since they’ll be dead before climate disaster hits, might as well gobble up as much $$$ as they can, while they can?

  2. fj says:

    Yes, as the magic of intelligence continues at profoundest levels and loftiest heights let’s hope that the latest crop of designer sorcerers not take distraction on dead-end vapid trends, ‘internet bubbles,’ ‘financial windfalls;’ but focus laser sharp saving civilization and the precious natural systems that support it.

    • Mulga Mumblebrain says:

      Ah, an idealist!

      • fj says:

        Nope, just a realist/pragmatist

        Perhaps from one of the cold calculating machine methods we use to describe our world (below) you might achieve insight into the importance of positivity bias in the ways we do things

        (Hint: the positive sign is understood)

        -3 + 2 = 2 – 3 = 2 + (-3) = -1

        3 – 2 = -2 + 3 = 3 + (-2) = 1

        • Mulga Mumblebrain says:

          All in vain. I’m innumerate, but I’ll take your word for it.

          • fj says:

            a big problem and you are not alone.

            numeracy is required for a sense of scale and doing the statistics often required for making good decisions, and more.

  3. Leif says:

    It sure would be nice in conjunction to keep the current climate disruptions at bay long enough to build out. Think jobs. GREEN JOBS! The best kind. Pay attention GOP. “Something is happening and you don’t know what it is, do you Mr. Jones.” Bob Dylan Ballard of a Thin Man, 1965.

  4. SecularAnimist says:

    There may be no such thing as a panacea … but ultra-cheap, ultra-efficient mass-produced photovoltaics sure looks pretty darned close to one.

  5. EDpeak says:

    Sounds good. Btw, what ever happened to this:

    Discovery may spur cheap solar power

    Thursday, October 2, 2003 Posted: 4:13 PM EDT (2013 GMT)

    “major European chip maker said this week it had discovered new ways to produce solar cells which will generate electricity twenty times cheaper than today’s solar panels.”

    “The French-Italian company expects cheaper organic materials such as plastics to bring down the price of producing energy. Over a typical 20-year life span of a solar cell, a single produced watt should cost as little as $0.20, compared with the current $4.The new solar cells would even be able to compete with electricity generated by burning fossil fuels such as oil and gas, which costs about $0.40 per watt, said Salvo Coffa, who heads ST’s research group that is developing the technology. ”

    “”Our target is fixed at $0.20,” said Coffa, who expects no major technological difficulties in going from prototypes to mass-produced commercial products. ”

    So whatever happened to this? Is the answer, “it went absolutely nowhere” as one is led to suspect by not hearing anything from them since about this? Or has it gone somewhere, moving forward, just much much more slowly?

  6. BBHY says:

    Solar power keeps getting better all the time. Batteries keep getting better all the time. Oil production keeps getting dirtier all the time.

    So, our politicians answer is more subsidies to fossil fuels.

    The big breakthrough we really need is a restructuring of the political system.

  7. Roger says:

    while I am reluctant to rain on the parade here, no one has (yet) demonstrated a plastic solar cell that lasts an appreciable amount of time — the photon flux blasts the polymeric structure to pieces.

  8. Mathew says:

    There are lobbies that DON’T want to change.

    They will do ALL to prevent any change.

    Nuclear , coal & petroleum etc are huge & will defend against all these Solar advances.

    They don’t want Solar ——

    Its all about more $$$$$$ for the rich.

  9. Dr.A.Jagadeesh says:

    Yes. The Solar Cell efficiency is increasing rapidly which will pave the way for wider usage of this CLEAN POWER.

    Dr.A.Jagadeesh Nellore(AP),India
    Wind Energy Expert
    E-mail: anumakonda.jagadeesh@gmail.com