nanosurface 2007-10-20 03:24
科学家研发出比毛发还细200倍的太阳能电池
[b][size=5]Nanowire generates its own spark[/size][/b]
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【纳米科技世界快讯】Scientists have developed solar cells 200 hundred times thinner than a human hair that they believe will power the nanoscale gadgetry of tomorrow.[/b]
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[img]http://img143.imageshack.us/img143/269/nanowire1810071435d38tc8.jpg[/img]
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[i]This nanowire converts light into electrical energy (Image: B Tian, Lieber Group, Harvard University)[/i]
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Professor Charles Lieber and colleagues at Harvard University have made silicon nanowire that can generate its own energy by converting light into electrical energy.];m0bzGA q7n x
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They publish their results today in the journal [i][b]Nature[/b][/i].jZy%J)B AW
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Nanoscale gadgets, from consumer devices to bioterrorism monitors and in-body diagnostics, often need a power source.
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But finding something that doesn't degrade or is efficient enough has been difficult.
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The researchers have made nanowire that's virtually invisible to the naked eye, a single strand of which can crank out up to 200 picowatts, or two hundred billionths of a watt./KG o3?_\a4g.G V
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That may not seem much. But at the nanoscale it is enough to provide a steady output of electricity to run ultra-low power electronics, including some that could be worn on, or even inside, the body.
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The scientists say it is also clean, efficient and renewable.
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"An individual nanoelectonic device will indeed consume very little power. But to do something interesting will require many interconnected devices and thus the power requirement, even for nanosystems, can be a challenge," Lieber says.\*o
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Monitoring bioterrorism threats, for example, would require an entire array of nanosensors, nanoprocessors to analyse the signals received, and nanotransmitters to relay information to a centralised facility, he says.
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Conventional sources, he adds, are "bulky, non-renewable and expensive" by comparison.
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Layers and layers
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The cable itself looks, at first sight, like the cables used to hook up cable television networks. Both have a core covered with two layers.
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But the similarity stops there. Besides being 100,000 times smaller, the nanowire is not made of metal but of silicon with three different types of conductivity arranged as layered shells.2lp]XU/d
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Incoming light generates electrons in the outer shell, which are then swept into the second layer and the inner core along micropores.5D&?B` e$U'A|'r
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These holes carry an equal, but opposite, charge as electrons, which means that the two particles move in opposite directions in the presence of an electric field.7One7x _J9o!iM
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Lieber says the electrically connected core and cladding, a kind of sheath, play the same role as the positive and negative terminals of a battery.v-Wi,kI G UA
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The researchers say that their nanowire converts 3.4% of sunlight into electricity and can withstand concentrated light without deteriorating.
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They say it costs about the same to make as other nanoscale photovoltaic devices and is up to 5% efficient.
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Commercial solar cells, by comparison, have efficiencies around 20%, the researchers say.
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source：ABC Science Online