Recombination Analysis in Cadmium Telluride Photovoltaic Solar Cells With Photoluminescence Spectroscopy

We used photoluminescence (PL) spectroscopy to study recombination in polycrystalline CdS/CdTe photovoltaic solar cells with open-circuit voltages in the range of 0.899-0.895 V. From PL emission spectra, we identified defects with an activation energy of 0.11-0.12 eV in the junction and back-contact regions. At < 100 K, lifetimes in devices were similar to those in single crystals and ranged from 300-400 ns. Strong lifetime temperature dependence at 100-300 K suggests the presence of a relatively shallow recombination center. Therefore, it is possible that in CdTe solar cells, lifetime is limited by relatively shallow defects.