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Power Science Technology

Not Transparent Aluminum, But Conductive Plastic 96

Posted by Soulskill
from the see-through-power-generator dept.
michaelmalak writes "Scientists at the US Department of Energy's Brookhaven National Laboratory and Los Alamos National Laboratory have fabricated transparent, thin films capable of absorbing light and generating electric charge over a relatively large area. The material, described in the journal Chemistry of Materials (subscription required), could be used to develop transparent solar panels or even windows that absorb solar energy to generate electricity. The material consists of a semiconducting polymer doped with carbon-rich fullerenes."
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Not Transparent Aluminum, But Conductive Plastic

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  • by Bigjeff5 (1143585) on Saturday November 06, 2010 @12:30PM (#34147638)

    It's transparent because the film has a hexagonal structure - extremely thin (and therefore transparent) at the center of the hexagon, thick (and therefore opaque) at the edges of the hexagons. The electricity is generated at the edges, as that is where the light is absorbed and that's where all the electrons are ready to be knocked off their molecules. It's not blocking certain wavelengths and allowing others through (well obviously to some degree it is, but not in the visible spectrum). It's blocking light in certain parts and allowing light through in others.

    It's basically going to tint the windows, how much will be determined by how densely the hexagons are packed - more hexagons means more electricity but also a darker tint.

  • by jo_ham (604554) <joham999&gmail,com> on Saturday November 06, 2010 @01:02PM (#34147752)

    It really depends what part of the spectrum it is absorbing in. If it absorbs strongly in the near IR region but completely passes visible, then how transparent it looks to us really isn't going to affect how efficient it is. Some chemical bonds just don't absorb energy in the visible region, which is hopefully what they are going for here, so that the primary function of the window itself is not compromised.

    Ideally you want to absorb the energy above the visible region - it's more energetic after all, but there's a huge range of the spectrum available to choose from, with only a small portion of it apparent to us as humans (at least through detection by our eyes - you can obviously perceive IR radiation directly and UV/Xrays/other ionising radiation indirectly with no instruments).

  • by znerk (1162519) on Saturday November 06, 2010 @01:06PM (#34147770)

    Some links that have more information, without having to give money to the Chemistry of Materials:

    http://news.discovery.com/tech/material-could-collect-sunlight-from-roof-and-windows.html [discovery.com]

    http://www.lanl.gov/news/releases/scientists_produce_transparent_light-harvesting_material.html [lanl.gov]

    Oh, and one more thing:
    Buckminster Fuller strikes again! AHAHAHAHAHAhahahahahaha... hah.

    --
    I want my Dymaxion [wikipedia.org]

  • by JustinOpinion (1246824) on Saturday November 06, 2010 @01:12PM (#34147804)

    It's transparent because the film has a hexagonal structure - extremely thin (and therefore transparent) at the center of the hexagon, thick (and therefore opaque) at the edges of the hexagons.

    Actually it's a little bit more interesting than that. In addition to being thinner at the center, the light-absorbing polymer is not well-ordered (amorphous) in the center region, which leads to it being worse at absorbing light. At the edges of the hexagons, the polymer orders better, which allows it to absorb light more efficiently. This makes the structure more intelligent, in principle: if the honeycomb structure acts as one half of the conduction pathway (necessary for a photo-voltaic), then it makes sense to have the material close to it do the light-absorbing, and have the material further away (center of hexagons) which cannot participate in light harvesting, just be transparent. So this in principle allows one to design more efficient semi-transparent solar cells.

    Peeling back the layers of hype a bit, however, these kinds of solar cells are horribly inefficient. The best materials we currently have to make plastic solar-cells ("organic photo-voltaics") have pretty poor efficiency. Making a solar cell that's semi-transparent just makes the efficiency (per unit area) even worse. But, this is fairly fundamental research: by demonstrating that they can tune the light-absorbing capabilities of the polymer based on its ordering (and control ordering by using the honeycomb patterning and preparation parameters), this provides useful information about how to make higher-performance plastic solar-cells. So this research may actually end up being more important for conventional solar cells ('opaque') than it is for window-coating solar-cells or whatever.

    P.S.: The materials used in the paper have an absorption maximum at 503 nm (green), so they probably create a purplish tint. The absorption spectrum can be tuned to change the tint, however this will impact the solar collection efficiency.

    Disclaimer: Some of the co-authors are colleagues of mine. However I wasn't involved in this work in any way.

  • by Animats (122034) on Saturday November 06, 2010 @01:14PM (#34147820) Homepage

    What's really going on in solar is that big US companies with real manufacturing expertise are moving in.

    • Dow Chemical [dowsolar.com] is about to release solar shingles. "About to release" means "passed UL certification last week" and "volume shipments in 2011". Solar enthusiasts have blithered about solar shingles for a decade, but Dow actually solved all the real world problems, like the roof not leaking, the interconnect system being safe, and the installation being do-able by a typical roofer.
    • General Eletric [gepower.com] is now active in solar. They make not only panels, but major parts you need to really get things done, like megawatt-sized inverters.
    • 3M [3m.com] now makes solar panels.

    This is where the action is. Solar is a heavy-manufacturing business, and it's the companies with experience in running big factories that are now taking over.

  • by Anonymous Coward on Saturday November 06, 2010 @02:26PM (#34148176)

    Humans are only able to "see" a very small portion of the spectrum of light. This leaves a lot of IR and some UV available for absorption without humans noticing.
    Wikipedia has a nice chart of the spectrum here [wikipedia.org]

  • by Black Gold Alchemist (1747136) on Saturday November 06, 2010 @02:43PM (#34148282)
    It's only part of the solar panel. I'm over-simplifying, but solar panels are a sandwich of three layers: the transparent conductor (currently indium doped tin oxide), the semiconductor layer (silicon), and the back collector (metal). This discovery will replace that pesky transparent conductor layer.
  • Re:Coming soon (Score:4, Informative)

    by the gnat (153162) on Saturday November 06, 2010 @02:45PM (#34148294)

    I work for the DOE (at a different lab), and from what I've seen, patented technology is almost always licensed to American companies. If it wasn't, a major argument for the existence of the national labs goes out the window, and Congress would probably throw a fit. I don't know if patent licenses come with strings attached (like "thou shalt not offshore manufacturing"), but my guess is that any company wanting to profit from publicly-funded basic research has to tread carefully.

    (Obvious disclaimer: I speak for no one except myself - I'm just a lowly programmer anyway.)

  • by spike hay (534165) <blu_ice@v i o l a t e . m e.uk> on Saturday November 06, 2010 @03:09PM (#34148380) Homepage

    The great majority of the sun's energy that reaches the surface is in visible. That's why we see in visible rather than NIR or ultraviolet, which have pretty much the same optical properties.

    The sun is pretty close to being a 5800K blackbody, which means that it emits primarily in visible, but also some UV and near infrared.

      However, the UV mostly gets cut off in the stratosphere by ozone (which is why the stratosphere is actually warmer that the upper troposphere). A good portion of the NIR is cut off by water and other stuff.

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