Photoluminescence Fatigue in CdTe Photovoltaics

Abstract

AbstractJunction photoluminescence intensity (PL) in polycrystalline CdTe/CdS solar cells gradually decreases over time, similar to the PL fatigue in chalcogenide glasses. We discriminate between the fatigue per se and concomitant short-time PL drop due to the laser heating. The fatigue is more profound at higher temperatures and laser beam powers and can be as large as 80 percent in two hours. We attribute the observed phenomenon to defect creation by the light-generated electrons and holes. The defects provide additional non-radiative recombination channels. Simultaneously, this negative feedback makes the defect-generation rate slowing down, so that the PL fatigue saturates.