Nano‐size Joule‐Heating to Achieve Low‐Ohmic Ag–Si Contact on Boron Emitters of n‐TOPCon Solar Cells

Abstract Over the past decade, Tunnel Oxide Passivated Contact (TOPCon) solar cells have emerged as a leading technology for high‐efficiency silicon solar cells. Conventional metallization processes using silver/aluminum (Ag/Al) pastes encounter significant hurdles due to reliability risks and insufficient contact quality. Recent advancements in laser‐induced metallization technologies, particularly laser‐enhanced contact optimization (LECO), offer promising solutions. However, the mechanism of silver‐silicon (Ag–Si) contact formation on the P+ emitter of TOPCon cells via LECO processing remains incompletely understood. This study designs and prepares two types of glass frits (GF‐A and GF‐B) for TOPCon cells and investigates the electrical properties of corresponding devices. Advanced techniques are employed to examine the Ag–Siinterfaces. The results demonstrate that GF‐A‐based TOPCon cells (Cell‐A) outperformed GF‐B‐based cells (Cell‐B) due to the construction of a current‐confined Ag–Si interface. A composite conductive model for the Ag–Si interfaces by LECO treatment is introduced, revealing the nano‐size Joule‐heating to achieve the Ag–Si eutectic structure as the underlying formation mechanism. This work contributes to the understanding of metal‐silicon contact optimization in solar cells and introduces novel methodologies for laser‐induced synthesis and micro‐nano interface engineering.