Nanowire makes own electricity

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.”