Record-Thin Light Absorber Offers New Solar Hope

Thin is in, from the peel-and-stick thin-film solar cells that Stanford University scientists described last year, to the super-thin, stackable solar cells MIT researchers recently conceptualized. Now Stanford is back with “the thinnest, most efficient absorber of visible light on record.”

It’s a wafer dotted with trillions of round particles of gold, nanodots about 14 nanometers tall and 17 naonmeters wide (a nanometer is a billionth of a meter).

“Achieving complete absorption of visible light with a minimal amount of material is highly desirable for many applications, including solar energy conversion to fuel and electricity,” Stacey Bent, a professor of chemical engineering at Stanford and co-author of the study, said in a statement.

thinnest light aborbers

Break image via Stanford University

The light spectrum isn’t just visible light, of course, with different waves ranging from 400 nanometers long to 700 nanometers long, but the Stanford team “tuned” its cell to absorb only visible reddish-orange light waves about 600 nanomaters long.

“The coated wafers absorbed 99 percent of the reddish-orange light,” fellow researcher Carl Hagglund said. “We also achieved 93 percent absorption in the gold nanodots themselves. The volume of each dot is equivalent to a layer of gold just 1.6 nanometers thick, making it the thinnest absorber of visible light on record – about 1,000 times thinner than commercially available thin film solar cell absorbers.”

Great stuff – but what’s the takeaway for you as a citizen of the world hoping renewable energy can rise up and slay the fossil fuel dragon?

Well, when it comes to solar cells, “This provides a benefit in minimizing the material necessary to build the device, of course,” Bent said. But there’s more.

“(T)he expectation is that it will also allow for higher efficiencies, because by design, the charge carriers will be produced very close to where they are desired – that is, near where they will be collected to produce an electrical current or to drive a chemical reaction.”

One thing that could make this breakthrough more viable is reliance on less-expensive material than gold. Yeah, the price has come down recently but it’s still very, very expensive. Maybe not for the Stanford team just making a few cells, but in terms of mass production.

“We chose gold because it was more chemically stable for our experiment,” Hagglund said. “Although the cost of the gold was virtually negligible, silver is cheaper and better from an optical point of view if you want to make a good solar cell. Our device represents an orders-of-magnitude reduction in thickness. This suggests that we can eventually reduce the thickness of solar cells.”

The Stanford research was published in the journal Nano Letters.

Sports columnist, newspaper desk guy, website managing editor, wine-industry PR specialist, freelance writer—Pete Danko’s career in media has covered a lot of terrain. The constant along the way has been a fierce dedication to knowing the story and getting it right. Danko's work has appeared in Wired, The New York Times, San Francisco Chronicle and elsewhere.

  • Donzell Jones

    when can we place orders for finished products that supply solar power?

    • Pete Danko

      Always difficult to know when — or even if — scientific research will filter down into products, and in what ways.

    • Pilot1095

      Probably about the time cancer is cured, the year 3018. In the meantime, these guys will continue to publish rubbish like this.

      • Pete Danko

        Rubbish? Wow. I’d be interested in hearing what aspects of the paper you believe to be flawed.

  • Donzell Jones

    hopefully behind LCD & Led screens on cell phones.

    • http://www.facebook.com/lorint Lorin Thwaits

      Well that’s silly. You do want ambient light to hit the panel, you know.

      • Donzell Jones

        Maybe on it’s own panel then.

        260 267 3687

  • JeffreyRodriguez

    Gold leaf is proabably significantly thicker than this application, but currently costs $26.93/sqft. If this became a popular commercial option it could be very good for gold.

  • JeffreyRodriguez

    Gold leaf is proabably significantly thicker than this application, but currently costs $26.93/sqft. If this became a popular commercial option it could be very good for gold.

  • Mark D. Little

    “One thing that could make this breakthrough more viable is reliance on less-expensive material than gold.”

    Have they considered trying to apply this method with carbon nanotubing? Since we’re going down to nanoscale and some fullerenes have proven to be more electrically conducive than copper…then in light of striving to avoid reliance on rare earth metals, well – you can’t get more abundant a resource than carbon. ;)

    M.D. – A.D.

  • Ken

    This is just Magnificent, very valuable research that will have an important place shortly – but how can we stop fracking

  • Ed Shafer

    Very cool. I like the concept of peel and stick as well. This implies you can put a few cells (or many) just where you might need them. Job well done. Kudos to Stanford U.