Posted on 10/23/2007 1:47:45 PM PDT by blam
Nanowire Generates Its Own Electricity
ScienceDaily (Oct. 23, 2007) — Harvard chemists have built a new wire out of photosensitive materials that is hundreds of times smaller than a human hair. The wire not only carries electricity to be used in vanishingly small circuits, but generates power as well.
Charles M. Lieber, the Mark Hyman Jr. Professor of Chemistry, and colleagues created the nanowire out of three different kinds of silicon with different electrical properties.
The silicon is wrapped in layers to create the wire. When light falls on the outer material, a process begins due to the interaction of the core with the shell layers, leading to the creation of electrical charges.
The idea of creating nanoscale photovoltaics is not new, Lieber said, but prior efforts used organic compounds in combination with semiconductor nanostructures that had lower efficiency and that degraded under concentrated sunlight. Lieber’s materials have several advantages, he said. The materials are more efficient, converting 3.4 percent of the sunlight into electricity; they can withstand concentrated light without deteriorating, gaining efficiency up to about 5 percent; and they’re as cheap to make as other related nanoscale photovoltaic devices.
“The real [question] is whether there’s a new geometry that will lead to better photovoltaic technology,” Lieber said. “We worked on coaxial geometry.”
The most recent development builds on Lieber’s considerable prior work on nanoscale devices. He has developed sensors with potential bioterrorism applications that can detect a single virus or other particle, nanowire arrays that can detect signals in individual neurons, and a cracker-sized detector for cancer.
A cheap nanoscale power source broadens the potential applications of such nanoscale devices. Though the tiny photovoltaic cells can generate enough electricity to power a similarly tiny circuit, Lieber said they’re not yet efficient enough to have applications on the scale of commercial power generation.
Commercial solar cells, he said, have efficiencies around 20 percent, compared with 3.4 percent for his nano-solar cells. One avenue of future research, Lieber said, will be to explore ways to boost efficiency of the nanowire photovoltaics. If they can reach 10 to 15 percent, he said, their lower cost of production — they can be made from relatively inexpensive materials and don’t require clean rooms to produce — may make them useful in larger-scale applications.
“There’s no physical reason it couldn’t be higher,” Lieber said. “I’m pretty optimistic that we’ll be able to track down the efficiency issue.”
Until then, Lieber sees a future for the nanowire photovoltaics in niche applications, such as multiple distributed sensors or durable, flexible devices, possibly sewn into clothing or worn as a patch.
“It will have to be unique to be an economically viable application, some place where you want durability and flexibility, where if it gets destroyed, people don’t care,” Lieber said.
The work was described in the Oct. 18 issue of the journal Nature.
Adapted from materials provided by Harvard University.
Won’t be long until the Libs whine about why more cars don’t have this technology or that the oil companies will buy it up. lol
Fascinating post. I’m thankful to God that I live in such incredible times and can marvel at our ever-expanding technological know-how.
If it could just replace the AA batteries in my kid’s toys it would be a miracle!
I like the sound of that! Will it keep my cigar lit?
And before you know it, the Chinese will be manufacturing nanowire...from lead.
Diodes have a voltage difference across the junction.
It is measurable, and has been used for years as a bias voltage. You can put them in series and get higher voltages.
Some electronic chips use this as a keep alive memory voltage. (normal memory chips lose their information when the voltage is disconnected). Chips that have stacked diodes will keep their memory.
I take it they have stacked them in a wire to make the “nano wire”.
This could really be a sort of holy grail. BMFLR.
6"/100's = very short 'wire'!
they’re as cheap to make as other related nanoscale photovoltaic devices.
I'm guessing that the more nano the scale, the more macro the cost/price?
He has developed sensors with potential bioterrorism applications that can detect a single virus or other particle, nanowire arrays that can detect signals in individual neurons, and a cracker-sized detector for cancer.
Ahhhh, COST EFFECTIVE, and useful usages!
their lower cost of production...
Lower cost per unit; or lower cost per watt?
You've made a great start, Professor Lieber; keep up the good work!
All we need now is big nano-wire and we can cut out the power plants.
> Diodes have a voltage difference across the junction.
Oh man. Yes, but only when there’s a current ...
Diodes do not hold a charge or otherwise _store_ energy in any meaningful way.
Some photovoltaic devices are diodes, yes, but generating electricity is not something that all diodes do.
Have you tried it?
Put a high impedance volt meter across a diode that is not in a circuit and you will get a voltage.
I learned that in basic electronics school. I just did it again right now. I have made my living in electronics for over forty years.
It is called contact potential and is used in electronics to provide a bias for various purposes.
You cannot draw current from it, other than a few micro amps to cause a meter to read it.
Again, using diodes to produce a voltage is nothing new. Putting a bunch in series will produce a higher voltage.
Thanks Blam, hadn’t seen this.
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