Influence of oxygen on Ag ionization in molten lead borosilicate glass during screen-printed Ag contact formation for Si solar cells

a b s t r a c t In order to gain further insight into the formation mechanism of fire-through Ag contacts of Si solar cells, the ionization of Ag during the dissolution of Ag powder into a lead borosilicate glass melt was electrochemically investigated at 800 ◦ C under various ambient conditions with different oxygen partial pressures (PO2 ). Voltammetric analyses of the Ag-free and Ag-containing glass melts confirmed that some of the Ag powder dissolved into the molten glass as Ag + ions through interaction of the powder with oxygen in the ambient atmosphere. The concentration of Ag+ in the molten glass significantly increased with increasing PO2 . The dependence of the Ag + solubility in the molten glass on PO2 was estimated from chronoamperometric measurements for a series of glass melts containing different amounts of Ag powder. The chronoamperometry results clearly demonstrated that the solubility limit of Ag + in the