The connections between dark rings and efficiency & the analysis of low efficiency in monocrystalline silicon solar cell

This study would show the connections between dark ring and transfer efficiency. Through testing, it is indicated that there is no necessary relation between the low efficiency and dark rings, also, the cells with dark ring are not low efficiency necessarily. Slight dark ring can be detected with photoluminescence (PL), but not detected with electroluminescence (EL). Research shows that dark ring relates to the uneven distribution of minority carrier lifetime and the efficiency of solar cell depends on the whole lifetime of the wafer. It is shown that the silicon raw material and cell processing are the two main reasons leading to the low efficiency, if the cell keeps high lifetime after striping its surface, the influence of the material can be excluded. Reprocessing this type of wafer, the high efficiency cell can be gotten.