Characterization of 24.3% Screen-Printed Cu-Contacted n-Type Tunnel Oxide Passivated Contact Solar Cell with Laser Enhanced Contact Optimization: Article No. 115053

Rising silver (Ag) prices are driving efforts to reduce metallization cost in n-type tunnel oxide passivated contact (n-TOPCon) solar cells, which rely on Ag contacts on both sides. Copper (Cu) is an attractive alternative due to its low cost, abundance, and comparable conductivity, but its rapid diffusion in silicon (Si) during screen-printed metallization can increase recombination and degrade cell performance. Combining Cu metallization with the laser-enhanced contact optimization (LECO) process, which enables low-temperature firing (540 degrees C) of the screen-printed contacts, can significantly reduce Cu penetration into the Si substrate. This paper demonstrates 24.3% Cu-contacted n-TOPCon solar cells using a post-firing LECO process along with counterpart Ag-contacted cells of 24.5%. The metal-induced recombination current density (J0, metal) of the Cu contact on the rear side poly-Si was only 14 fA/cm2, about four times lower than Ag. Before LECO, contact resistivities of Ag and Cu contacts to n-TOPCon were 5.5 m..omega..-cm2 and > 100 m..omega..-cm2, respectively, which decreased to 1.7 and 19.7 m..omega...cm2 after optimized LECO. To compensate for higher contact resistivity of Cu, we increased the Cu coverage on n-TOPCon from 7% to 18% by adding more gridlines, yielding ~ 24.3% efficiency. Quokka 3 device simulations validated the measured parameters, and power loss analysis showed that the?~?0.2% efficiency gap between Ag- and Cu-contacted cells is mainly due to higher contact resistivity and line resistance of Cu. Combining screen-printable Cu paste with LECO enabled high-efficiency Cu-contacted n-TOPCon cells, offering a viable pathway to reduce Ag in solar cell manufacturing.