Kinetics of light induced changes in protocrystalline thin film materials and solar cells

Studies have been carried out on the kinetics of light induced changes in thin films and solar cells fabricated in different laboratories. Unlike the many studies on undiluted a-Si:H films the kinetics reported here are for 1 sun illuminations carried out to the degraded steady state (DSS). The light induced changes at temperatures from 25 to 100°C were characterized with electron mobility lifetime products and subgap absorption in films and fill factors in solar cells. The significant changes in the degradation kinetics that occur in these materials in this temperature range have further confirmed the importance of charged defects, not only in the annealed state, but also in the degraded steady states. Results are also presented on corresponding solar cell structures, which also indicate that defects other than neutral dangling bonds have to be taken into account if any meaningful evaluation is to be made of their solar cell properties