Carrier-induced degradation phenomena of carrier lifetime and cell performance in boron-doped Cz-Si

Fundamentals of the solar cell performance degradation phenomenon, specific to Czochralski silicon have been intensively investigated. Simulations for the solar cell performance degradation, using PC1D and measured carrier lifetime data, clearly explain the actual cell performance degradation, as a result of the carrier diffusion length degradation. The investigations under various stress conditions confirm that injected excess carriers are responsible for the defect reaction. The role of injected carriers in the defect reaction is discussed. Multi-step decay, which consists of the initial rapid degradation and a second double exponential degradation, is one of the significances of the phenomenon. Distinct activation energy of the defects for the initial degradation is obtained, which suggests several types of the substitutional-B-interstitial-O-related defects for the degradation. However, very similar activation energies for the defect annihilation are obtained for both the initial and the second degradation.