An Evaluation of Constituents in Paste for Silicon Solar Cells with Floating Contact Method: A Case Study of Tellurium Oxide Effects

Abstract

Metallization contacts on emitter of silicon solar cells cause shunting of p-n junction and induce carrier recombination, resulting in a loss in open-circuit voltage Voc of the cells, which must severely limit cell efficiency. But, the mechanism of the shunting and the recombination has not been understood enough yet, especially on the contacts with conductive paste, because the shunting and the recombination caused by the paste come of multiple effects of each constituent in the paste such as silver metal, glass frit, and some additives. Thus, the effects of the each constituent in the paste should be clarified to elucidate the mechanism and to achieve an advanced paste for high-efficiency silicon solar cells. In our previous study, effects of aluminum in silver/aluminum paste and effects of glass frit itself on the shunting and the recombination in n-type solar cells were clearly shown by using “floating contact method”, and its effectiveness on the paste evaluation were demonstrated in the solar cells. In this study, the floating contact method was applied to conventional p-type solar cells with silver paste to clarify effects of tellurium oxide on the silver paste, because the detailed effects of the tellurium oxide on the shunting and the recombination have not been clear yet even though the oxide is widely used for commercial paste. Our study clearly shows that the tellurium oxide reduces the shunting and the recombination caused by the silver paste in the solar cells, and also demonstrates the effectiveness of the floating contact method on the paste evaluation.