Novel photovoltaic ribbon technology: Interfacial behavior of In–50Sn alloy ribbon without metal matrix under electrothermal effects and chlorine corrosion

In this study, an In–50Sn alloy ribbon without a metal matrix was developed as a substitute for traditional dipped-photovoltaic (PV) ribbons. In–50Sn alloy ribbon reflowed directly onto an Ag electrode on a Si solar cell, and the formed Ag–In intermetallic compound (IMC) was used to connect the Si substrate and PV ribbon. Only one IMC layer was formed in the In-50Sn PV module structure. After bias aging or thermal aging tests, electrothermal effects influenced the interfacial structures, but the IMC and series resistance of the module structure did not increase substantially. NaCl immersion was conducted to evaluate the corrosion resistance of the In–50Sn PV module. Chloride ions preferentially corrode the interface between Ag paste and a Si solar substrate, causing poor bond reliability. Modules with a reduced amount of Ag paste were used on the Si solar substrate and achieved bond strength that met the industry standard. The PV ribbon without the metal matrix limited IMC growth and thus resulted in a module with a long operating lifetime.