Light and elevated temperature induced degradation (LeTID) of N-type TOPCon solar cells

Till now, N-type tunnel oxide passivated contact (TOPCon) solar cells are emerging as a leading technology owing to their high energy conversion efficiency and low-cost. However, the performance of N-type TOPCon solar cells is affected by light and elevated temperature-induced degradation (LeTID) during operation, and the underlying degradation mechanisms have not yet been fully revealed. This study investigates the underlying LeTID mechanisms with commercial N-type TOPCon solar cells by comparing and analyzing impact parameters such as hydrogen content in the passivation layer, rapid thermal anneal temperature, doping strategy, initial efficiency, silicon wafer quality, and oxidation degree. We further integrate light injection technology to mitigate LeTID effects and found the light injection technology is beneficial to activating hydrogen passivation processes, improving surface stability, increasing the average open-circuit voltage, and reducing the relative efficiency degradation from -0.23% to +0.32%. The research findings not only deepen the understanding of LeTID degradation, but also pave the way for enhanced reliability and widespread adoption of N-type TOPCon solar cells.