Potential process design and control for solar cell lean production in future

In this paper, the correlation between wafer quality and cell efficiency was studied to identify the key impact factors, such as effective lifetime, impurities and defects. Standard (STD, 2.94E21atoms/cm3) and lightly doped emitter (LDE, 1.08E21atoms/cm3) diffusion were investigated for different qualities wafers. For high impurities wafer, cell efficiency of STD diffusion is 0.44%_abs higher than that of LDE diffusion due to the better gettering by bulk lifetime and iron concentration measurement; for high defect wafer, cell efficiency of STD and LDE are similar; for good wafer (high lifetime, low defect and low impurities), LDE diffusion is better than STD with 0.08%_abs higher cell efficiency due to the better blue wavelength response by using IQE measurement, which should be higher if optimizing firing condition for Fill Factor improvement. Therefore, the possible wafer sorting provides opportunities to design and control different cell process for different incoming wafers to enable the best possible output in a lean production in future.