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, 2007, 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.�
Further Information and Source:
-
Bozhi Tian, Xiaolin Zheng, Thomas J. Kempa, Ying Fang, Nanfang Yu,
Guihua Yu, Jinlin Huang & Charles M. Lieber: Coaxial silicon nanowires as solar cells and nanoelectronic power
sources.
In: Nature
449, 885-889 (18 October 2007); doi: 10.1038/nature06181
