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Power Hardware Science

Graphene Creates Electricity When Struck By Light 132

Posted by Soulskill
from the it-slices-it-dices dept.
MrSeb writes with news out of MIT about another interesting and potentially useful property of graphene. Researchers have known for several years that graphene generates electricity when exposed to sunlight, but incorrectly attributed it to the photovoltaic effect. A new paper shows that the current is actually generated from the much more unusual 'hot-carrier' response. Quoting: "The material’s electrons, which carry current, are heated by the light, but the lattice of carbon nuclei that forms graphene’s backbone remains cool. It’s this difference in temperature within the material that produces the flow of electricity. ... Such differential heating has been observed before, but only under very special circumstances: either at ultralow temperatures (measured in thousandths of a degree above absolute zero), or when materials are blasted with intense energy from a high-power laser. This response in graphene, by contrast, occurs across a broad range of temperatures all the way up to room temperature, and with light no more intense than ordinary sunlight." It will take more work to determine what new applications are reasonable from an efficiency perspective, but it does broaden graphene's already-impressive capabilities.
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Graphene Creates Electricity When Struck By Light

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  • Re:Again? (Score:2, Insightful)

    by Anonymous Coward on Friday October 07, 2011 @02:01PM (#37641586)

    Producing in the labs vs producing in a manufacturing setting is worlds apart simply. Depending on the technology, there are lots of reasons why some takes decades to reach the market while others never reach it at all.

    These include:
    1) economic viability (the technology costs too much)
    2) production viability (difficult if not impossible to produce at a large scale) which may require manufacturing technology to be developed as well or simply is impossible due to it's nature
    3) technological issues (which the technology shows great interests but requires dealing with issues that must be addressed first before it can be used)

    In this case, graphene, while many breakthroughs have been made with the materials, it still requires much more research as there are alot of issues to deal with and things we still don't understand about it.

  • Re:Again? (Score:5, Insightful)

    by Rei (128717) on Friday October 07, 2011 @02:29PM (#37641946) Homepage

    Because people like you never notice how much things actually *are* changing here in the real world.

    Batteries are my favorite example. I'm constantly hearing people complain about reporting on battery breakthroughs in the lab, sarcastically saying, "Yeah, but when are we actually going to see these in the real world?" -- forgetting how much radically smaller and/or longer lived rechargeable batteries have gotten for increasingly high-power-consumption consumer electronics. Secondary cells have 5x'ed in energy density since the late 80s, and the trend shows no signs of slowing down. Even li-ion seems to have good life left in it (in particular, the anode; silicon (derided on Slashdot as a "sure, when will we finally see THAT?" tech) is now starting to replace carbon for part of the anode materials in commercially available cells, and it has a maximum theoretical anode energy density 10x that of carbon). Li-ion cathodes probably have a good 50% improvement left in them, possibly more; we'll probably see a migration to a Li-S chemistry after that, since that seems to be maturing the fastest (barring unexpected breakthroughs in Li-air, other chemistries, or electrostatic storage).

    One nice thing about Li-S is that it's lower cell voltage with a much higher cell capacity, meaning that it's easier to get a specific desired voltage. Electrostatics would obviously be best (durability, temperature sensitivity, voltage discharge curve, etc), but they've also got the longest way to go. Li-air is oft hyped, but it too has an awfully long way to go. Then there's all sorts of other longer-shot contenders out there -- nickel-lithium, sodium-ion, aluminum secondary cells, etc. And then the question of whether flow batteries of any given chemistry will ever compete outside of a very narrow range of applications (such as grid storage).

  • by DrgnDancer (137700) on Friday October 07, 2011 @02:45PM (#37642168) Homepage

    Long story short... no. First, that isn't how science works. If I'm an expert in photovoltaic reactions, my help isn't very helpful while you're trying to get a windmill working. Scientist are, in general, specialists, there is no degree in "cool alternative energy technology". Second, that's not how markets work. If I'm really close to figuring out how to, say, increase solar cell efficiency by 50%, thus making me rich; I'm unlikely to give up that work because we're working on wind power this month. Finally, it would be foolish to put all of our eggs in one basket. It's unlikely that any currently feasible alternative energy systems will be able to supply all the power people need everywhere.

    Deserts are great for solar, coastline are get for wind and hydro, volcanically active areas are great for geothermal... None of them is a perfect tech that will work everywhere. Seattle would find solar farms all but useless, and there's not much easily available geothermal in Detroit. There are a few "magic bullet" technologies being researched, but they are very theoretical and a risky "bet the farm" idea. Sure, controllable and safe fusion power would solve all our problems, but no one is entirely sure it's possible.

  • Re:Again? (Score:4, Insightful)

    by GameboyRMH (1153867) <gameboyrmhNO@SPAMgmail.com> on Friday October 07, 2011 @02:51PM (#37642252) Journal

    A comedy site, yes, but the article was based on verifiable facts. And I did verify many of them because I was shocked at the level of stupidity.

The secret of success is sincerity. Once you can fake that, you've got it made. -- Jean Giraudoux

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