Advancing Nickel Seed Layer Electroplating for Enhanced Contact and Passivation Performance in Topcon Solar Cells

Electroplating copper technology offers advantages such as low cost, good conductivity, and a simple process, making it a promising solution in the photovoltaics (PV) field. However, despite its effectiveness in reducing silver consumption, a significant challenge arises from suboptimal electrical contact between metal electrodes and the polycrystalline silicon films, limiting the application of electroplating techniques in tunnel oxide passivated contact (TOPCon) solar cells (SCs). In this study, we propose a simple method to enhance the quality of electrodeposited metals and improve contact performance with polycrystalline silicon films by lowering the electrodepositing temperature for nickel seed layer. Additionally, we optimize contact properties by modulating nickel deposition time and annealing temperature. This process results in excellent physical and electrical contact performance, achieving the lowest contact resistivity of 0.19 mΩ·cm2 and the improved adhesion strength. Ultimately, TOPCon SCs using low-temperature plated seed nickel and copper metal electrodes achieve an efficiency of 23.90%, which is attributed to advance the application of optimal nickel seed layer electroplating.