NANOWIRE GENERATES ITS OWN ELECTRICITY http://xrl.us/7d4m
and/or www.mantra.com/jai
Nanowire generates its own electricity
Microscopic wire has photovoltaic properties
Alvin Powell
Harvard News Office
October 17, 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 work was described in the Oct. 18 issue of the journal
Nature.
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.
- President and Fellows of Harvard College
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hhc...@yahoo.com
> Om Shanti
>
> Hindu Holocaust Museumhttp://www.mantra.com/holocaust
>
> Hindu life, principles, spirituality and philosophyhttp://www.hindu.orghttp://www.hindunet.org
>
> The truth about Islam and Muslimshttp://www.flex.com/~jai/satyamevajayate
Wow. all that I can say if "Good Luck Guys".
Don't let he door hit you in the ass on your trip back to home!
Harry C.
Bob Eld
<use...@mantra.com and/or www.mantra.com/jai (Dr. Jai Maharaj)> wrote in
message news:20071103G54jVFg7a5l8Hc55y5uz6ol@SN920...
Not very impressive. Even if the efficiency is made higher, the wires very
small size means it intersects very little light on an area basis so how
could they be useful?
Of course if the nano wires are produced as a "fur" or fuzz with trillions
of them per square meter, maybe the combined area could be greater than the
footprint. There might be something to that but it's hard to imagine how
they could be cheap to produce or how they would be connected.
zzbu...@netscape.net
> <use...@mantra.com and/orwww.mantra.com/jai(Dr. Jai Maharaj)> wrote in
> messagenews:20071103G54jVFg7a5l8Hc55y5uz6ol@SN920...
It's useful because like the article stated, it's not a
light collector. You put circuits in the thing, rather than
idiots like sci.physics.
>
> Of course if the nano wires are produced as a "fur" or fuzz with trillions
> of them per square meter, maybe the combined area could be greater than the
> footprint. There might be something to that but it's hard to imagine how
> they could be cheap to produce or how they would be connected.- Hide quoted text -
>
> - Show quoted text -