<p>This article reports the important role of crystalline phases of tellurite glass in enhancing the performance of photovoltaic Ag pastes. It was found that Pb₂Te₃O₇ and PbTeO₃ crystals had been grown in tellurite glass after heat treatment. When the crystallized glass was used in photovoltaic Ag pastes, the energy conversion efficiency of crystalline Si solar cells had increased by 0.52 to 0.73 percentage points. This enhancement was attributed to the significant increase in open-circuit opening voltage and filling factor of the cells. Microscopic observation of the Ag–Si contact interface revealed that during the sintering of the Ag paste, the crystallization of the glass resulted in a delayed sintering and a shorter reaction time, which may protect the Si surface from excessive etching. By comparison between Pb₂Te₃O₇ and PbTeO₃ cases, it was inferred that the ratio of PbO and TeO₂ in the crystalline phase not only affected the sintering of the Ag paste on the Si surface, but also the size, number, and distribution of Ag crystallites at the Ag–Si interface. To further elucidate this issue, three binary glasses with PbO-TeO₂ ratios of 1:3, 1:1 and 2:1, respectively, were investigated. The results show that with the increase of PbO proportion, on the one hand, the softening temperature of the glass increased and the fluidity decreased, and on the other hand, the glass dissolved less Ag, precipitated more Ag, and enhanced the erosion of the Si surface. Current study shows that glass crystallization can be an optional means in addition to glass composition, which can be used to more finely control the sintering behavior of Ag paste on the Si surface.</p>