Bias-dependent photoluminescence in CdTe photovoltaics

摘要

We show that external bias significantly affects the photoluminescence (PL) in CdTe photovoltaics. The main observations are: (1) reverse bias suppresses PL, (2) PL increases with moderate forward bias and tends to saturate when it is above the open-circuit voltage, and (3) PL in the region of saturation is extremely sensitive to device degradation. We attribute the observed phenomena to the competition between the field-induced separation of electrons and holes and their nonradiative recombination. We have developed a model that describes bias-dependent PL more quantitatively and forms a basis for using it as an indicator of device degradation.