Spectrally and time resolved photoluminescence analysis of the CdS/CdTe interface in thin-film photovoltaic solar cells

Light absorption and charge separation in thin-film polycrystalline cadmium telluride (CdTe) photovoltaic (PV) solar cells largely occur in the vicinity of the CdS/CdTe interface. Sulfur alloying at this interface to form CdSxTe1-x and doping with Cu appear to be important for efficient PV devices. Based on the different band gaps of CdSxTe1-x and CdTe, we apply spectroscopic and computational photoluminescence (PL) analysis to characterize this interface. We find that Cu concentration changes the dynamics of charge separation and PL emission intensities from the CdSxTe1-x and CdTe regions. We have determined charge separation lifetime and minority carrier lifetime, and we have estimated minority carrier mobility as <100 cm2 V−1 s−1.