Wednesday, February 11, 2009

Nanocrystals Shown to Generate More Than One Electron Per Absorbed Photon

This is rather interesting, especially when I missed all the controversy regarding the earlier, similar claim.

Scientists out of Los Alamos have reconfirmed their findings that in certain nanocrystal, one absorbed photon can produce more than one free electron in the conduction band.

When a conventional solar cell absorbs a photon of light, it frees an electron to generate an electrical current. Energy in excess of the amount needed to promote an electron into a conducting state is lost as heat to atomic vibrations (phonons) in the material lattice. Through carrier multiplication, excess energy can be transferred to another electron instead of the material lattice, freeing it to generate electrical current—thereby yielding a more efficient solar cell.

Klimov and colleagues have shown that nanocrystals of certain semiconductor materials can generate more than one electron after absorbing a photon. This is partly due to strengthened interactions between electrons squeezed together within the confines of the nanoscale particles.

If this finding is true, then one immediate direct implication is that one could produce a more efficient solar cells.

I'll try to hunt for the exact reference (I hate press releases like this since they do not include the exact citation) and post it here when I find it.


1 comment:

Valerie said...

There's a lot more about this in a New Scientist article, which includes references to papers in PRL and Nano Letters