The Staebler–Wronski Effect (SWE) refers to light-induced metastable changes in the properties of hydrogenated amorphous silicon.
They showed that the dark current and photoconductivity of hydrogenated amorphous silicon can be reduced significantly by prolonged illumination with intense light.
More recently, the H collision model proposed that two spatially separated recombination events cause emission of mobile hydrogen from Si–H bonds to form two dangling bonds, with a metastable paired H state binding the hydrogen atoms at a distant site.
[3] The efficiency of an amorphous silicon solar cell typically drops during the first six months of operation.
In a typical amorphous silicon solar cell the efficiency is reduced by up to 30% in the first 6 months as a result of the Staebler–Wronski effect, and the fill factor falls from over 0.7 to about 0.6.