Posted: March 24, 2008 |
Nanowires may light your home |
(Nanowerk News) Light-emitting diodes that give a warm glow to your home or office will be available within a few years, say Swedish researchers working with nanowires.
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Professor Lars Samuelson and team at Lund University are aiming to produce devices that do not cast as harsh a light as existing LEDs, and that are more efficient and longer lasting.
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"We can really make the three colours - red, green and blue - with this technology and get warm LEDs," says Samuelson, who presented his research at the recent International Conference On Nanoscience and Nanotechnology in Melbourne.
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Conventional LEDs are made of multiple crystalline semiconductor layers that emit light when a current passes through them, converting 30% of the electricity they receive into light.
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But these LEDs are often used in small applications like torches, bicycle lights and reading lamps, rather than on a larger scale.
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This is because defects in the crystal structure of the semiconductors limit their efficiency when scaled up.
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"Even the commercial LEDs you buy today for your flashlight, for instance, have 10 million defects per square centimetre," says Samuelson, of the university's Nanometer Structure Consortium.
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Samuelson's team have found a way to produce what they say are defect-free LEDs.
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Forests of nanowires
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The researchers have been making LEDs out of forests of long, thin nanowires grown from gallium arsenide and indium gallium phosphate.
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Millions of these nanowires, each 2 micrometres tall and less than 200 nanometres in diameter, produce "highly perfect structures", says Samuelson.
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He says they will last longer and be useful in large-scale home and office lighting, with an efficiency of around 50%, more efficient than existing incandescent or fluorescent lighting.
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By comparison, an incandescent light bulb is only 4% efficient, a compact fluorescent 25%.
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The nanowire LEDs are brighter than existing LEDs and can emit light more easily to their surrounds, Samuelson says.
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They can be tuned to give warm colours, by adjusting the concentration of different elements in the crystalline structure.
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New crop of LEDs
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Samuelson says the research has been funded by Swedish and European research programs and he is involved in a start-up company to commercialise large-scale LED lighting within the next three years.
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Other researchers are working towards warmer LEDs for use in home lighting using methods other than nanowires.
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But nanowire LEDs are expected to be the most efficient, says Australian nano-engineering expert Professor Chennupati Jagadish of the Australian National University's Research School of Physical Sciences and Engineering.
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