Minority carrier lifetime measurements on silicon solar cells under concentrated sunlight

The effects of concentrated solar irradiance and temperature on minority-carrier lifetime in high-efficiency silicon concentrator solar cells were studied. A variation on the conventional open-circuit voltage decay lifetime measurement method allowed lifetime measurements while the cell was illuminated. Lifetime slowly increased with temperature over the range of 10 to 80 C under constant irradiance. Lifetime measurements were taken at previously unreported intensities up to 214 suns (one sun = 100 mW/sq cm). Beyond 15 suns lifetime monotonically decreased. Solar cell modeling on the semiconductor simulation program PC-1-D suggested that the measured lifetime in the base region becomes dominated by carrier junction into the emitter and back-surface recombination, accounting for lifetime degradation at higher irradiance levels.