Carbon Nanotubes for Solar Cells...

September 15, 2003

Carbon Nanotubes for Solar Cells

Carbon nanotubes--tiny strawlike cylinders of pure carbon--have interesting
electrical properties. Indeed, they have already been used to manufacture
tiny transistors and nanowires. Now scientists say the minuscule cylinders
may one day find their way into solar cells. Researchers report in the
latest issue of the journal Angewandte Chemie International Edition that
they have succeeded in tweaking the tubes so that they supply electrons when
exposed to visible light.

To make the altered nanotubes, Dirk M. Guldi of the University of Notre Dame
and his colleagues attached molecules of ferrocene to their walls. Made up
of two flat rings of five carbon atoms each that sandwich an iron atom,
ferrocene is known for its tendency to give up its electrons. The scientists
determined that when they exposed their altered nanotubes to light in the
visible range, carbon atoms in the walls of the tubes accept the electrons
originally associated with the ferrocene molecules. "This separation of
charge is sufficiently long-lived for us to divert and use the electrons,"
Guldi notes.

This is the first time hybrid nanotube complexes have been shown to undergo
such photoinduced electron transfer. And it didn't take much: the
researchers added just one ferrocene group for every 100 carbon atoms in the
nanotubes. The results, Guldi remarks, meet "the first criteria for the
development of solar cells based on modified carbon nanotubes." --Sarah
Graham
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Do Wah Ditty

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