Screen Printable Silver Paste For Silicon Solar Cells With High Sheet Resistance Emitters

In silicon solar cells, forming good ohmic contact between the emitter and the metal with minimum contact resistance is critical to achieve peak electrical performance [1]. In commercial solar cells, screen printable silver paste is commonly used to form contact. Factors related to paste chemistry, process conditions and the solar cell wafers influence the contact quality. In this paper, the effect of paste chemistry and emitter sheet resistance on contact quality is described. Several paste chemistries were tested for contact resistance with Transmission Line Model (TLM) measurements on wafers with sheet resistance between 45-100 Ω/□. The series resistance of the solar cells was recorded over 50 °C firing window. The paste chemistry was further refined to form low resistance contacts on solar cells with emitter sheet resistance on 100 Ω/□.