Metastable Defects Decrease the Fill Factor of Solar Cells

Solar cells are made from semiconductors, which inevitably include defects. The defects in Cu(In,Ga)Se${}_{2}$ (CIGS) known to be metastable: With excitation they change character, can have a profound impact on device function. authors show that these metastable reduce the efficiency of solar cell due an increased diode factor. It is possible measure this quantity directly bare absorber (without needing build entire cell), yielding lower limit for whole device. Experiments and simulations indicate must reduced increase efficiency, not just CIGS-based cells.