Why solar cells lose potency

Commercial products such as laptop computer monitors and solar-powered calculators are constructed from a light-sensitive material with a peculiar problem: When exposed to intense light, it forms defects, reducing the efficiency of the solar cells by 10 to 15%.

Scientists have been pondering this flaw since the 1970s, because the material – hydrogenated amorphous silicon, or a-Si:H – has important applications for solar energy generation. A new study reported in the June 13 issue of the journal Applied Physics Letters, however, suggests that Ohio University scientists may have found the root of the problem.

When this photovoltaic material 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.