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Solar Cells That Emit Light Break Efficiency Record

Posted by samzenpus on from the shine-on dept.

benfrog writes "Researchers at the University of California-Berkeley say they have come up with a counter-intuitive way of making solar cells more efficient — making them emit light. In a press release the scientists claim to be the first to demonstrate that the better solar cells are at emitting photons (the more LED-like they are), the more efficient they are at generating electricity. However, 'unlike an LED, the electrons in a solar cell are absorbing photons from an exterior source as well as emitting their own.'"

9 of 139 comments (clear)

  1. Idea by busyqth · · Score: 5, Funny

    Why don't they just funnel the emitted light back to the solar panels and thus make them independent of an external light source?
    This would be great for space colonies and sea-floor dwellings.

    1. Re:Idea by X0563511 · · Score: 5, Funny

      In this seafloor habitat dwelling we obey the laws of thermal dynamics!

      --
      For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
    2. Re:Idea by Daniel_Staal · · Score: 5, Informative

      Because the light will be of lower energy (and therefore of a different wavelength) than that which the solar cells absorbed.

      Basically, instead of heating up, these cells emit the energy in a controlled manner, in semi-directed infrared (probably) radiation. No laws of thermodynamics are being bent: The waste product is just closer to the type of the input than in other solar cells.

      You could similarly say that a water turbine is more efficient if it lets water flow out: It is. The water will just have less flow strength than it did when it went in. The difference is what the turbine is collecting as energy. In this case, instead of letting the light 'back up' in the solar cells (as heat), it's released.

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      'Sensible' is a curse word.
  2. What's counter-intuitive about it? by SirGarlon · · Score: 5, Informative

    If you've taken sophomore college physics, it's not counter-intuitive at all that an efficient absorber is also an efficient emitter.

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    [Sir Garlon] is the marvellest knight that is now living, for he destroyeth many good knights, for he goeth invisible.
    1. Re:What's counter-intuitive about it? by gman003 · · Score: 5, Funny

      What do you think "intuitive" means exactly?

      Intuitive (adj.) - Anything I already know.

    2. Re:What's counter-intuitive about it? by Eponymous+Hero · · Score: 5, Insightful

      as a slashdotter, the rest of us slashdotters presume that you're a more-than-competent physicist, chemist, biologist, astronomer, economist, engineer, gamer, proofreader, and Dr. Who/BSG/Star Trek/Star Wars/Matrix/LOTR archivist. if you're not, someone who is will pull your card.

      plus, isn't sophomore college physics, like, a facebook app or something by now?

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  3. Well, kind of by Anonymous Coward · · Score: 5, Informative

    Ideally, you would want all of your electron-hole pairs to never recombine (which would keep them from emitting photons). Since that's obviously not possible, this would be the best possible outcome of internal recombination.

  4. The bigger problem by cirby · · Score: 5, Interesting

    Sure, it would be nice to have much more efficient solar cells, but there's another issue keeping costs up.

    It's the home infrastructure.

    Right now, it costs more to install the solar cells on a roof than it does to make them, and once you add in the cabling and battery/storage system for balancing the load or for nighttime use, the actual power generating part of the system is much less than half of the whole system cost. Increasing efficiency is great, and will let you cut the overall size of the system for a similar capacity, but the big issue is making a solar system that's easy to install, with cheap storage, for a lot less.

    Cheap batteries and inexpensive support systems are the things we need now...

  5. No joke by Memophage · · Score: 5, Funny

    Guess I can't tell that joke about a solar-powered flashlight anymore.