Carbon nanotubes could be used to make efficient solar cells.Byline: ANI Washington, September 11 (ANI): Using a carbon nanotube See nanotube. instead of traditional silicon, Cornell University Cornell University, mainly at Ithaca, N.Y.; with land-grant, state, and private support; coeducational; chartered 1865, opened 1868. It was named for Ezra Cornell, who donated $500,000 and a tract of land. With the help of state senator Andrew D. researchers have created the basic elements of a solar cell solar cell, semiconductor devised to convert light to electric current. It is a specially constructed diode, usually made of silicon crystal. When light strikes the exposed active surface, it knocks electrons loose from their sites in the crystal. that hopefully will lead to much more efficient ways of converting light to electricity than now used in calculators and on rooftops. The researchers fabricated, tested and measured a simple solar cell called a photodiode A light sensor (photodetector) that allows current to flow in one direction from one side to the other when it absorbs photons (light). The more light, the more the current. Used to detect light pulses in optical fibers and other light-sensitive applications, it works the opposite of a , formed from an individual carbon nanotube. Led by Paul McEuen, the Goldwin Smith Professor of Physics, and Jiwoong Park, assistant professor of chemistry and chemical biology, the team described how their device converts light to electricity in an extremely efficient process that multiplies the amount of electrical current that flows. This process could prove important for next-generation high efficiency solar cells The use of solar cells for the generation of electricity has been mainly limited by their poor efficiency and high exploitation costs. But over the last years, research has been focussed on developing high efficiency solar cells. , according to the researchers. "We are not only looking at a new material, but we actually put it into an application - a true solar cell device," said first author Nathan Gabor, a graduate student in McEuen's lab. The researchers used a single-walled carbon nanotube, which is essentially a rolled-up sheet of graphene, to create their solar cell. About the size of a DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. molecule, the nanotube A carbon molecule that resembles a cylinder made out of chicken wire one to two nanometers in diameter by any number of millimeters in length. Accidentally discovered by a Japanese researcher at NEC in 1990 while making Buckyballs, they have potential use in many applications. was wired between two electrical contacts and close to two electrical gates, one negatively and one positively charged. Their work was inspired in part by previous research in which scientists created a diode, which is a simple transistor that allows current to flow in only one direction, using a single-walled nanotube. The Cornell team wanted to see what would happen if they built something similar, but this time shined light on it. Shining lasers of different colors onto different areas of the nanotube, they found that higher levels of photon energy had a multiplying effect on how much electrical current was produced. Further study revealed that the narrow, cylindrical structure of the carbon nanotube caused the electrons to be neatly squeezed through one by one. The electrons moving through the nanotube became excited and created new electrons that continued to flow. The nanotube, they discovered, may be a nearly ideal photovoltaic cell because it allowed electrons to create more electrons by utilizing the spare energy from the light. This is unlike today's solar cells, in which extra energy is lost in the form of heat, and the cells require constant external cooling. (ANI) Copyright 2009 Asian News International The Asian News International (ANI) agency provides multimedia news to China and 50 bureaus in India. It covers virtually all of South Asia since its foundation and presently claims, on its official website, to be the leading South Asia-wide news agency. (ANI) - All Rights Reserved. Provided by Syndigate.info an Albawaba.com company |
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