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Power Technology

Berkeley Lab Develops Technology To Make Photovoltaics Out of Any Semiconductor 55

Posted by samzenpus
from the easy-solar dept.
First time accepted submitter bigvibes writes "A technology that would enable low-cost, high efficiency solar cells to be made from virtually any semiconductor material has been developed by researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley. This technology allows for plentiful, relatively inexpensive semiconductors, such as metal oxides, sulfides and phosphides that had previously been considered unsuitable for solar cells because of the difficulty in tailoring their properties by chemical means."
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Berkeley Lab Develops Technology To Make Photovoltaics Out of Any Semiconductor

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  • by John Bokma (834313) on Sunday July 29, 2012 @02:24PM (#40809525) Homepage
    as usual :-)
    • That's about when I'll be building a house from scratch.
      • Re: (Score:2, Funny)

        by Anonymous Coward

        Build?
        I expect to be able to print my house.
        http://www.psfk.com/2012/02/3d-printing-buildings.html

    • as usual :-)

      I was thinking closer to never actually, as they've been posting stories here about vastly improved solar panels for more than 5 years. If I remember all the stories correctly, and I think my math is pretty accurate on this one, we can now build 500% efficient, spiral-shaped, multi-layer, extra thin cut, impossibly cheap, magical divine solar panels sent down from Mt Olympus to power mankind. Maybe someone should manufacture one then, huh?

  • progress marches on
  • *yawn* (Score:5, Informative)

    by sycodon (149926) on Sunday July 29, 2012 @02:32PM (#40809595)

    call me when I can buy it in rolls or sheets at Home Depot.

  • by Anonymous Coward on Sunday July 29, 2012 @02:33PM (#40809603)

    “screening-engineered field-effect photovoltaics,” or SFPV

    The two hyphenated pairs get a single letter. The single compound word gets two letter. Stop the madness!

    • Re:Acronym abuse (Score:4, Informative)

      by Samantha Wright (1324923) on Sunday July 29, 2012 @03:10PM (#40809859) Homepage Journal

      There's an easy explanation for that: the second "E" disappears when you say it quickly (ess ee fee ee pee vee), and the first one would make the initialism long and unwieldy without providing pronounceability. "PV" describes the root noun and hence is more important to the meaning of the term, and makes it easier to infer what the abbreviation describes when scanning snippets of unfamiliar literature. Irregularity in such contractions is not a new thing, though—ever seen "Wm." for "William"?

      Brevity, especially the minimum effort to provide disambiguation, supersedes consistency; otherwise we wouldn't use abbreviations at all. Think of it like Huffman coding. Huffman coding is the wellspring of life.

      • by meekg (30651)

        Booyah!
        Sharp as a laser beam, powerful as the diode bank that's driving it. Analogies are not my thing.
        The second line should be enshrined and worshipped. Neither are accolades.
        So yeah, Booyah!

    • “screening-engineered field-effect photovoltaics,” or SFPV

      The two hyphenated pairs get a single letter. The single compound word gets two letter. Stop the madness!

      Perhaps these guys were smart enough to realize that SFP has already been abused beyond recognition for many and diverse causes [wikipedia.org] and they needed to add (at least) another letter in order to stop the madness.

    • I do get a feeling that the government tax dollars will go straight to equipping a Chinese factory, however. Nearly all high tech industries are set up such that US does the research and Asia does the manufacturing and reaps the profits.

      • Well, when the US tries to encourage local companies and startups to take advantage of new technologies, and it backfires, then the government gets blamed (see the Solyndra kerfluffle.) Can't win.
        • by Crypto Gnome (651401) on Sunday July 29, 2012 @07:11PM (#40812257) Homepage Journal

          Well, when the US tries to encourage local companies and startups to take advantage of new technologies, and it backfires, then the government gets blamed (see the Solyndra kerfluffle.) Can't win.

          Yes but Made In China has nothing to do with that.

          Made In China: because our environmental controls are effectively nonexistent compared to yours.

          Sure there's cost-of-labor (etc) factors too but in these High-Tech (ie lots of mostly toxic chemicals somewhere in the manufacturing process) industries, cost of containing (or more often than not, cleaning-up-after) pollution is prohibitive.

          Someone needs to educate these companies that doing all your toxic production in a foreign country is functionally equivalent to a goldfish swimming to the other side of the bowl to take a crap.

  • by Grayhand (2610049) on Sunday July 29, 2012 @03:30PM (#40810007)
    The issue was always a low output but if you can make them dirt cheap who cares if they are 5%? If you can cheaply replace the shingles on your house with cheap solar cells I'd call it a win even if you have to cover the whole roof instead of one part. Cheap and practical will always win over efficient and expensive. Even when over the long term you are better off with the more efficient cells people will actually buy the cheaper ones. It's what keeps Ikea and stores like it in business. Pressboard furniture falls apart after a couple of years but it's less than half the price of decent furniture. A good piece may last 50 years and out live 10 cheapie pieces so the cheap furniture costs 5X as much in the long run but people still go for cheap. If people could cover their roofs for $2,500 to $5,000 instead of $15,000 to $35,000 most roofs would have solar cells even if they last half as long.
    • by Dr. Spork (142693)
      You're forgetting that the cost of transportation and installation is really quite high compared to the cost of the cells. Then there's all the wiring, and the expensive conversion hocus pocus that you need to safely make the power you generate come out of the socket at 120/60. These fixed costs will bite you in the ass if you skimped on the cells themselves and they're only 5% efficient and barely making a dent in your power bills. To pay back for the total installation costs, the cells really do need to h
    • by cjsm (804001)
      Another factor is PV is getting cheaper and better all the time. So buy the cheap stuff now, and upgrade in a few years to PV that's significantly better and cheaper than the high end PV was when you did the original installation.
    • yah don say! In regards to the cost of real furniture, I can find good quality real wood made in the USA for the same price as the crap pressboard sold by HomeDepot/Lowes and Walmart. What's that? Yep, there's quite a few places, most are local or within driving distance that make furniture from Pine and such and that's what I buy as it's better quality for the same damn price

    • If you can cheaply replace the shingles on your house with cheap solar cells I'd call it a win even if you have to cover the whole roof instead of one part.

      Hail decides who wins.

  • by purpledinoz (573045) on Sunday July 29, 2012 @03:47PM (#40810211)
    It's really hard to picture what is described in the article. Here's a link to an article with a diagram. [lbl.gov]
  • by LourensV (856614) on Sunday July 29, 2012 @04:27PM (#40810529)

    I read the article (I know! But there were no comments yet, so what am I to do?) and, not having understood much of it, did some reading to try and understand what's going on here. I think I've more or less figured it out, so I'm attempting a simple explanation here. Semiconducting physics nerds, please fix this for me as appropriate.

    Atoms consist of a positively charged nucleus, surrounded by one or more shells of electrons. Electrons farther away from the nucleus have more energy than ones closer in. Put a bunch of those atoms together, and there are two things that can happen. In some materials, the electrons in the higher energy states are so "far away" from the nucleus in energetic terms, that they can easily move from one atom to the next. These materials are conductors. In other materials, there is a big gap (the band gap) between the highest "bound" (valence band) energy state, and the minimum energy state (the conduction band) needed to move between atoms. So, the electrons can't move away from their nuclei, and these materials are electrical insulators. Then there are some materials that have an intermediate sized gap between stuck valence states and free-to-move conduction states, and these are called semiconductors.

    A solar cell works by the photoelectric effect: when an incoming photon (e.g. sunlight) hits an electron in a semiconductor, the electron absorbs the photon and its energy increases. If the photon is energetic enough, this will move the electron from the valence band to the conduction band. This also creates a positively charged "hole", where the electron was before. The electron and the hole attract each other because they have opposite charge. Left to their own devices, they'll just recombine, so in a solar cell, an electric field is applied. This moves the electron in one direction, and the hole in the opposite direction (because of the opposite charge). This moving electrical charge is otherwise known as current flow, and so we have a working solar cell.

    So how do we make an electric field? In normal photovoltaic cells, this is done by doping (adding small impurities, typically boron and phosphorus to) the semiconductor. Since these have less or more electrons in their outer shells, they create areas in the semiconductor with more electrons or more holes, which creates a charge difference between them (a P-N junction). This charge difference creates an electric field, which will whisk away any electrons and holes created within it. Apparently, this doping process only works for relatively expensive semiconductors however.

    So, if I understand correctly, what these researchers have done is to apply an external electric field, by applying a small voltage across the whole thing. This puts a charge on the contacts on each side of the cell, which draws electrons in the semiconductor one way and holes the other way, thus creating a P-N junction without doping. The problem is that normally the construction of the contacts keeps their electric field from propagating into the semiconductor, so that it doesn't generate a good P-N junction. Apparently they've overcome this by changing the geometry of one of them, in two different ways for two different alternative semiconductors. And then they have a version in which the external voltage is supplied by the cell itself, making it self-contained.

    So is this useful? Well, conspicuously absent from the article is any mention of efficiency. So I'd speculate that this mainly allows the production of low-efficiency solar cells at lower prices than before, rather than getting more output from your roof. But if this makes solar cells cheap enough to just blanket anything and everything with them, that could still be useful of course.

    • by Anonymous Coward on Sunday July 29, 2012 @04:42PM (#40810671)

      Pretty good summary! The journal article (http://pubs.acs.org/doi/full/10.1021/nl3020022) discusses efficiencies for silicon, a well understood semiconductor used as a test case. The effect can improve silicon Schottky barrier cells from 8% to almost 20% efficiency. (Note that Schottky cells are a metal-semiconductor junction, not the typical commercial chemically-doped silicon that gets around 20-25%.)

      The exciting thing about this technique is that you can now take low-efficiency (10%) Schottky or heterojunction cells made with (literally) dirt-cheap materials (rust, sulfides, etc) and convert them into low-cost, high-efficiency (perhaps ~15-20%) cells. Then the module cost is low, and the installation costs can be low too (as you don't need to buy as many panels and cover as much ground for a certain amount of generated power).

    • by Ryanrule (1657199)

      Oh noes, all the college is coming back to me. Why didn't I bang that one chick, who cares she had a bf.

    • by gaelfx (1111115) on Sunday July 29, 2012 @09:49PM (#40813505)

      You know, reading this gave me an idea. /. should have something like this for every article (or at least articles such as this that require some explanation). they could make a competition out of it, and feature the winning comment in some way that makes it easy for us laymen to see when we choose to view the comments. Just a thought.

      Nice explanation, btw. I never really understood what an electric field was before!

    • To summarize the summary, the researchers managed to create a PN junction by applying an electric charge rather than doping.
  • by gaelfx (1111115) on Sunday July 29, 2012 @09:27PM (#40813363)

    To quote Bart Simpson: "I can't believe it! You actually found a practical use for geometry!"

  • Have we forgotten the term 'vaporware'? Has it evaporated along with the products we used to laugh at?

    I've been reading about 'exciting new developments' in photovoltaics for forty years, along with the flying car that's just around the corner and similar fantasies perpetuated by Popular Science & Popular Mechanics magazines.

    Show me the cheap efficient PV product I can buy today or just shut up.

    • by Anonymous Coward

      Not how science works, buddy -- research is hard and long term and needs occasional puff pieces to remind people it's worthy of funding. Photovoltaics is a tough nut to crack -- it's essentially competing with solar energy that's been accumulating and concentrating for millions of years (fossil fuels). Practical photovoltaics have only been around since the 1950s -- that fact that we're already close to grid parity in only a lifetime of research is a miracle.
      Reminiscent of this: http://www.youtube.com/wat

  • Solar panels are already cheap enough for me. In NYC, Con Ed charges $0.20+ per KWh, so installed panels at about $3:Wp pay off in under 7 years: a 14% ROI, better than the stock market ever gets (so I almost wish they cost more :).

    My problem is that my roof is largely covered by trees, so I get only about 20% of the sunshine past them. So I've been considering building a platform above the roof, above the trees, though that's going to be something like 10m above the roof, which is about 7m above the ground

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