Interfacial regulation and welding performance enhancement of front Ag electrodes in TOPCon solar cells via hybrid glass frit

With the advancement of photovoltaic technology, the mechanical and electrical reliability of Ag electrodes has become increasingly critical, emerging as a key bottleneck limiting module lifetime and power output. This study addresses the performance optimization of glass frits in the front-side Ag paste of tunnel oxide-passivated contact (TOPCon) solar cells by proposing a hybrid high and low temperature glass frit system to enhance solder joint reliability. Two base glass frits, L1 (high melting point) and G1 (low melting point), were prepared via the melt-quenching method. The hybrid glass frits, designated as M1, M2, and M3, were obtained by blending the base frits in mass ratios of 5:5, 7:3, and 3:7, respectively. A systematic investigation was conducted on the physicochemical properties, thermal behavior, and wetting characteristics of the hybrid glass frits, as well as their effects on the interface structure of the Ag electrode, grid line morphology, and soldering performance. Results indicate that the hybrid glass frits effectively broaden the melting range, optimize high-temperature viscosity and wetting behavior, and significantly improve the compactness and uniformity of the Ag-Si interface. By precisely adjusting the mixing ratio, the properties of multiple glass components can be synergistically combined to enhance the adhesion between the busbar and the Si substrate while dynamically optimizing the bonding speed between the solder and the Ag layer. This approach markedly improves the soldering reliability of solar cells. Among the samples, M2 (L1:G1 = 7:3) demonstrated the best soldering performance, with an average pull force of 4.304 N and the highest practical soldering rate, effectively enhancing the reliability of busbar soldering. This study offers a new direction for material design in photovoltaic Ag pastes.