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This thesis focuses on the characterization of a-Si:H/c-Si solar cells by simulated and quantitatively measured photoluminescence (PL). Different passivation layers on identical (p)c-Si substrates are compared in terms of splitting of quasi-Fermi levels EFn-EFp derived from PL, which gives the maximum achievable Voc. Effective lifetime Tau eff,pl and its intensity dependence are also calculated. Using the advantage of PL as a contactless method, consecutively processed layers during device deposition are analyzed. The results show that the interface defect density Dif in a-Si:H/c-Si heterojunctions strongly influences EFn-EFp. The comparison of EFn-EFp from PL with simulation allows the extraction of parameters for the interface. Tau eff,pl increases with temperatures T while PL yield decreases. This is explained by a reduction of the band-band recombination coefficient for higher T. Simulation of carrier densities and EFn-EFp shows the high sensitivity of these variables for different Dif at Voc. Finally, the differences between a PL-I-V-curve and the I-V-characteristics from a-Si:H/c-Si solar cells are analyzed. |
