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Scientists Develop Solar Cell That Can Also Emit Light

Posted by Soulskill on from the bidirectional-photon-technology dept.

An anonymous reader writes: "Scientists at the Nanyang Technological University have developed a solar cell that not only converts sunlight into electricity but also emits light as electricity passes through it. Tuning the composition of the solar cell enables it to emit different wavelengths of light (abstract), and because it is only about 1 micrometer thick, the material is semi-translucent and therefore could potentially be used in windows. The solar cell is comprised of the semiconducting mineral perovskite, which has been studied as a replacement for silicon in solar panels since 2009. Perovskite solar cells are not yet as efficient at energy conversion as silicon solar cells, but gains in this area of development coupled with cheaper manufacturing costs (10-20 cents per watt projected as opposed to 75 cents per watt with silicon solar panels and 50 cents per watt with fossil fuels) make perovskite a popular subject matter in the solar cell industry."

19 of 79 comments (clear)

  1. Heinlein? by Cpt_Kirks · · Score: 3, Interesting

    Didn't Heinlein come up with a similar concept? In the story with the moving roads?

    1. Re: Heinlein? by Bill_the_Engineer · · Score: 3, Informative

      Actually it was a short story called "Let there be light!" published in May 1940. Friday was published in 1982.

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      These comments are my own and do not necessarily reflect the views or opinions of my employer or colleagues...
    2. Re: Heinlein? by Alomex · · Score: 3, Insightful

      And/ I can come up with a concept in a novel about a very clean, efficient family car that spits into four when needed and rejoins into one when going for vacation.

      That took a minute of my time. Still the entire credit would go to whoever actually built such contraption.

  2. Back asswards by Tablizer · · Score: 2

    "Ralos Cell"

    --
    Table-ized A.I.
  3. Infinite energy! by kheldan · · Score: 3, Funny

    o Solar cell that also emits light
    o Sandwich it with a perfect mirror
    o Short the leads together
    o Infinite energy!

    --
    Are YOU using the TOOL, or is the TOOL using YOU? Think about it!
    1. Re:Infinite energy! by galloog1 · · Score: 2

      The military uses them in form software that does not allow for special formatting. It could be out of habit.

    2. Re:Infinite energy! by Anonymous Coward · · Score: 2, Funny

      No, you got it wrong, it's to the tune of "O Tannenbaum"

      O Solar cell, that emits a light,
      O Sandwich it with a perfect mirror,
      O Short the leads together, dear,
      Infinite energy, and free beer.

    3. Re:Infinite energy! by camperdave · · Score: 3, Insightful

      o Since when is the lowercase "O" a bullet?

      Since Slashdot stopped honouring the <OL> and <UL> HTML codes.

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      When our name is on the back of your car, we're behind you all the way!
  4. Yin and Yang by Dan+East · · Score: 5, Interesting

    Speakers can be used as microphones.
    LEDs can be used to detect light.
    Motors can be used as generators.
    Now some solar cells can emit light.

    Problem is it's matter of efficiency, which is always more of a one way street.

    --
    Better known as 318230.
    1. Re:Yin and Yang by Sir+Holo · · Score: 4, Insightful

      Absolutely brilliant comment. Also, you are correct.

      For those who didn't get this post: A transducer is a transducer. It can go either direction, as the physical mechanism is the same, whether one direction or the other. For example, electromagnets move a speaker cone to create sound. Yell at a speaker, and the sound pressure will generate a small voltage (a microphone).

      When poster called it a "one way street," he was referring to the way we engineer and design these transducers. They are optimized, for example to produce sound accurately. This inevitably leads to design trade-offs and optimizations for a particular application. That's all. No one is threatening the second law.

      When land-line phones were wired (not cordless), I discovered as a child that I could yell into the earpiece, which modulated the voltage on the line, and a faint sound could be heard at the other end. The implications for eaves-droppers was that removing the microphone from your phone handset would not render you undetectable to the other people on the line, precisely for the reasons above.

  5. Perovskite is a mineral ... but this isn't it by qparadox · · Score: 5, Informative

    When the article references perovskites, it is referring to a crystalline structure similar to the mineral perovskite (calcium titanate). These solar cells are NOT made of calcium titanate, nor is calcium or titanium even in them. Instead, they are make of organic - inorganic halides, in this case: CH3NH3PbX3 (where X = Cl, Br, I). The proper wikipedia link for the summary is: https://en.wikipedia.org/wiki/...

  6. Solar cell that emits light.... by Anonymous Coward · · Score: 3, Funny

    Any solar cell will emit light ... if you run enough current through it.

    1. Re:Solar cell that emits light.... by camperdave · · Score: 4, Funny

      Any solar cell will emit light ... if you run enough current through it.

      Ah yes! Reminds me of the smoke emitting diodes I used to play with as a young lad.

      --
      When our name is on the back of your car, we're behind you all the way!
  7. Cents per Watt by q4Fry · · Score: 2

    Can someone who understands the subject matter better than I do please explain to me how "cents per watt" is an applicable comparative metric for fossil fuels and solar cells?

    It would (at least apparently) seem to me that when you use a unit of fossil fuel, it is gone. By contrast, if you have a solar cell, it will continue to be useful for as long as the sun and the cell have line of sight.

    So aren't fossil fuels inherently measured in Joules?

    1. Re:Cents per Watt by Maury+Markowitz · · Score: 5, Informative

      > Can someone who understands the subject matter better than I do please explain
      > to me how "cents per watt" is an applicable comparative metric for fossil fuels and solar cells

      The price of electricity is basically the total money you put into running the plant over its lifetime divided by the total amount of power you get out of it during that lifetime. That's called the "levelized cost of electricity" or LCoE.

      For plants that don't use fuel - wind, hydro, PV - the total amount of money is basically the price of the plant, the price of repairs and operations, and the price of borrowing the money to pay for the first two. For systems that go up in a short time, like wind and PV, the costs are utterly dominated by the price of the equipment.

      For other sources the total cost of operations varies. Nuclear plants use fuel, but so little of it that it's not a major factor. However, these plants have enormous up front costs and decades long building cycles, so their LCoE tends to be utterly dominated by the prevailing interest rate. Coal and natural gas plants cost about 1/4 that of a nuclear plant and are therefore more heavily dominated by fuel costs, so their cost of operations goes up and down with the cost of the fuel.

      So when you're trying to compare the price of a PV plant to a coal plant, for instance, the key metric in the case of PV is the cost of the panels. That's because there's no fuel cost and almost zero maintenance (had mine 5 years, done exactly $0 work on them so far).

      Since the amount of sunlight shining in a particular area is averaged over long periods and available online, you can then predict the amount of power the plant will produce over its lifetime. For instance, in Toronto 1000 W worth of panels (i.e., a set of panels that will produce 1000 watts under specific conditions) will produce about 1200 kWh of power every year, after all conversion losses are factored in. We expect those panels to last about 25 years. So then

      LCoE = (cost in cents/watt * size of system in watts) / (25 years * 1200 kWh * system size in KILOwatts)

      So let's say the system, *all in*, costs you $3.50 a watt (about right these days). Then if you put up a system with 12 panels like mine, you get

      LCoE = (3.50 * 3000) / (25 * 1200 * 3) = 11.66 cents/kWh

      I think you'll find that is very comparable to what you are paying from your local utility, which is why PV is the fastest growing power source in the world today.

      This same basic formula can be used with any power source, but the inputs will differ. For instance, the equivalent number for a nuclear power plant is about 7500 to 8000 kWh per kW of panels installed, because they run full out 24/7, or at apt 85% full power, or "capacity factor". But as you might expect, construction costs are much higher, about $8/W or more (that plant in Florida came in at about $11/W, which is why they cancelled it).

      Likewise, wind turbines here in Ontario average about 30% "capacity factor" (CF), so that's about 2600 kWh/kW. That sounds bad until you consider they cost about $2/W installed. So when you compare the two head up it's something like (2 / 0.3) = 6.66 for wind vs. (8 / 0.85) = 9.41 for nuclear, which is why wind is the second fastest growing power source on the planet.

      And that's why we measure everything in terms of cents per watt. If you know that (although dollars per watt is the typical figure) and the capacity factor, everything else sort of disappears. So you can get a *very* good idea of the economics simply by dividing the ($/W) by (CF).

      If you'd like to do this on your own, with real numbers and more factors, you can. It's actually very easy and you can run through a given location in about 2 minutes:

      http://matter2energy.wordpress.com/2012/05/21/green-apples/

  8. Solar panels that emit light by SimonInOz · · Score: 2

    So we could have a torch (sorry, flashlight) that only works in sunlight ... ? I'm not sure I'd buy one of those.

    --
    "Cats like plain crisps"
  9. "Cheaper manufacturing costs" from phys.org by Animats · · Score: 2

    Another one of those "nanomaterial" stories. Claims of "cheaper manufacturing costs" for a product not yet produced in volume. Yet another "solar cell made with printing technology" scheme. Sigh.

    So this thing is one micrometer thick and they want to print it on windows. How long does it last, hammered by UV and weather and thermal cycling? Lifetimes for silicon solar panels are now up to 25 years (warranties are available for that long), and there's falloff in output over that time. Can a 1 micrometer film match that? Realistically, it's going to have to be behind a protective layer. Maybe it could be on the surface of the middle layer in double-pane glass, but now you have a complex sandwich to manufacture. There goes the "cheap manufacturing".

    Vertical windows are poorly oriented for capturing power. Solar shingles are better oriented. (Also, they exist, and you can buy them now.) And, as the head of Applied Material Solar pointed out a decade ago, half the cost is installing the thing. These guys need better numbers to back up their cost claims.

    1. Re:"Cheaper manufacturing costs" from phys.org by Mspangler · · Score: 2

      "Vertical windows are poorly oriented for capturing power."

      In the winter a south-facing vertical window does pretty well with the winter sun being rather low in the sky if you are 40 degrees or more of latitude.

  10. Pfft by Hamsterdan · · Score: 4, Funny

    That's nothing, while learning electronics as a kid, I invented a way to turn LEDs into Smoke Emitting Diodes...

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