Saturday, June 18, 2005

Why Solar Cells Lose Potency

Science Blog has an interesting article about why solar cells lose potency under high levels of radiation.
When [hydrogenated amorphous silicon, or a-Si:H] is exposed to intense light, hydrogen atoms move into new arrangements in which some silicon atoms become bonded to two silicon and two hydrogen atoms, creating a structure called silicon dihydride, or SiH2, said David Drabold, Presidential Research Scholar and professor of physics and astronomy at Ohio University, who co-authored the paper with graduate student Tesfaye Abtew and P. C. Taylor, Distinguished Professor of Physics at the University of Utah.

It's a process analogous to what happens when light hits photographic film, Drabold explained. Light prompts small clusters of silver atoms to accumulate at the surface and form an image. In the case of the photovoltaic material, however, light makes hydrogen atoms move, which creates undesirable defects.

Now that they know what's happening, the next step is to figure out why. With more research, they could improve solar cells.