Observation of the Contact Formation of PV Frontside Pastes by in-situ Contact Resistance Measurement

A large number of solar cell front side contacts is still produced by printing and firing of glass containing silver pastes. The role of the glass frit in the short firing cycles is not fully understood so far. To overcome this, an in-situ contact resistance measurement method was introduced. This examination method allows a time correlation of phase transport and reaction related phenomena and can be used as a basis for specific operations in the paste development. Thereby, the in-situ contact resistance curves of glass-containing silver metallization could be assigned to microstructural phenomena such glass melting, silver solution, ARC etching and silver precipitation. The results of the correlations between electrical characteristics and the formed microstructures confirmed the decisive importance of the glass phase in the silver metallization for contact formation processes.