Efficiency improvement of passivated emitter and rear cells using annealing process before surface passivation

Thermal annealing and effective surface passivation are significant to achieve high conversion efficiency (eta) of passivated emitter and rear cells (PERC). Thus, we added an annealing process before front and rear surface passivation in the existing production line. We found that the front recombination current (J(0,f)) and the rear recombination current (J(0,r)) of annealed PERCs are both lower than baseline PERCs without annealing process, which means better defect repair and passivation effect were achieved. And the average eta of annealed PERCs reaches 21.79%, which is 0.23% absolutely higher than that of the baseline PERCs. After that, we further explored the influence of gas composition (0%, 5% and 10% oxygen concentration in nitrogen atmosphere) during annealing process. We found that as the oxygen concentration increases, J(0,f)s and J(0,r)s of annealed PERCs (0%, 5%, 10%) are all lower than those of baseline PERCs. Meanwhile, the annealed PERCs (0%, 5%, 10%) get the average eta of 21.77%, 21.82% and 21.84% respectively, possessing absolute efficiency increase over the baseline PERCs with the average eta of 21.67%. The present work could help enhance the understanding of passivation property and improve the performance of industrial PERC cells.

Automated summary

The study demonstrates that adding an annealing process in the production line can enhance defect repair and passivation effect of PERC cells, leading to improved conversion efficiency. Additionally, the research investigates the influence of gas composition on the annealing process.