Improving n-TOPCon solar cell printing conditions and performance analysis by local dot contact approaches

This study investigates the optimization of printing conditions for n-TOPCon (n-type Tunnel Oxide Passivated Contact) solar cells to enhance their efficiency and performance. Key parameters varied include, dot print type, co-firing belt speed, and paste application method. Experiments conducted on n-type Cz silicon wafers analyzed the impact of high-temperature TOPCon Ag paste and low-temperature HIT (Heterojunction with Intrinsic Thin layer) paste on cell performance. The highest efficiency of 22.57 % was achieved at a belt speed of 100 ipm (inch per minute) with the incorporation of low-temperature HIT paste in a single dot printing configuration. Similarly, at 130 ipm, an efficiency of 22.15 % was obtained under optimized conditions. The fill factor (FF) significantly improved, achieving an FF of 79.66 % at 100 ipm and 78.63 % at 130 ipm. The optimal belt speed of 130 ipm was found to offer the best compromise between enhancing cell efficiency and minimizing potential thermal damage. The best short-circuit current density (J_sc) of 41.70 mA/cm² was achieved at 100 ipm, while the highest open-circuit voltage (Voc) of 0.69007 V was recorded at 130 ipm. Loss analysis indicated that efficiency and FF improvements were primarily driven by superior passivation and reduced contact resistance. This comprehensive study underscores the critical role of optimizing printing conditions to enhance n-TOPCon solar cell efficiency, contributing to more efficient and cost-effective photovoltaic technologies.