Investigations on CdSexTe1-x/CdTe Solar Cells Before and After a Light Treatment

CdSexTe1-x/CdTe solar cells are fabricated in the pilot line at CTF Solar with an efficiency of up to 21 %. Investigations were made on samples both directly after device processing and after a hot open-circuit light soaking (hOCLS) treatment. The hOCLS treatment generally leads to a substantial improvement of the IV performance, but behavior is not always consistent between cells. Most cells maintain a stable Jsc, but some show a significant loss in this parameter. In this study we try to explain this difference using IV measurements, EQE, SEM cross sections, EBIC, XRF thickness measurements, and front band alignment determination from PES sputter depth profiles. Investigations indicate a reduction in current contribution from the front of the CdSexTe1-x absorber, arising from change of the p-n junction. The band alignment at the front interface is investigated for different samples and different treatment in hOCLS by a PES sputter depth profiling.