Potential‐Induced Electrochemical Corrosion in Crystalline Silicon Solar Cells

In this article, the electrochemical corrosion of full‐area aluminum back‐surface field (Al–BSF) and bifacial passivated emitter and rear cell (PERC) crystalline silicon (c‐Si) solar cells subjected to different potential in sodium chloride (NaCl) solution is systematically investigated. Based on different potential‐induced corrosion, the electrochemical corrosion mechanism of c‐Si solar cells is revealed for the first time. Under zero potential, an important finding is that the silicon beneath silver electrode is corroded and perforated for Al–BSF cells. This phenomenon is attributed to the interaction between hydroxide ions from galvanic corrosion and electrons from silicon corrosion. For bifacial PERC cells, the pyramidal structure of silicon surface beneath the aluminum finger is observed at zero potential, which is similar to the silicon texturing etched in alkaline environment. Additionally, it is found that silicon corrosion is inhibited when positive or negative potential is applied to the back of Al–BSF and bifacial PERC cells. Moreover, it is observed the aluminum suffers from more serious corrosion at positive potential than that at zero or negative potential, which is attributed to synthetical results of galvanic corrosion and electrolytic corrosion. In this work, a new insight on the potential‐induced electrochemical corrosion for c‐Si solar cells is provided.