The substitutional B-interstitial O-related defects induced under an illumination, specific to B-doped Czochralski-grown silicon (Cz-Si), results in a solar cell efficiency loss of up to 3%. For a fundamental interpretation, the relationship between the solar cell performance and the minority-carrier lifetime degradation, and influence of the illumination conditions were investigated. A simulation of the cell performance degradation clearly represented that the degradation was explained as a result of the carrier diffusion length degradation. From a spectroscopic illumination investigation, the degradation was found to be independent of the stress-light wavelength. A blue light illumination on a solar cell resulted in the red response degradation, suggesting that the injected carriers activated the defect in the bulk. However, the correlation between carrier injection level and the cell performance decay time was nonlinear. The observed decay times were almost independent of the illumination intensity in the range of 1 to 100 mW/cm2. This trend appeared more significantly on cells with a higher base resistivity. From the experimental results, the role of excess carriers in the defect activation was discussed.
The rapid initial degradation of Czochralski-grown silicon (Cz-Si) solar cell performance has been investigated. The initial rapid degradation occurs at the beginning of the degradation process and is followed by a second slower degradation. The surface effect due to interface state degradation between the passivation layer and the Si substrate was investigated on several kinds of Cz-and float zone Si (FZ-Si) wafers. Carrier lifetime degradation induced by an illumination for 30 s was observed on every Cz-Si wafer, but no degradation was observed on FZ-Si wafers. Moreover, only the decrease of IR response of a cell was observed as a result of the initial degradation. The results suggest that the degradation occurs in the bulk. The magnitude and decay time of the degradation appear to depend on the wafer resistivity. Defects very similar to boron-oxygen complexes specific to Cz-Si were considered to be responsible. The distinctly small activation energy of 0.19 eV was obtained for the initial degradation, which suggests a fundamentally different defect reaction process. The activation energy of 1.6 eV for the defect annihilation process was obtained for both defects as well.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.