Effects of thermal budget in n-type bifacial solar cell fabrication processes on effective lifetime of crystalline silicon

摘要

The effects of residual C on cell properties are investigated from the view point of thermal budget in the n-type bifacial cell processes. Implied V_oc obtained from wafers with same O_i concentration depend on the thermal budgets decreases as the C_s concentration increases. The V_oc values vary depending on the wafer with different growth cooling rate. To analyze the effect of thermal budget correspond to solar cell fabrication process, CZ wafers with almost the same O_i concentrations are prepared. One of the wafers with relatively high residual C_s concentration shows the longer lifetime than the initial value after the 950 oC annealing step. On the other hand, the lifetime of a wafer with relatively low C_s concentration dramatically decreased by the same process due to the O segregation. These results suggest that it is important to choose appropriate wafer specification, starting with feedstock material, for increasing the solar cell efficiency.