The concentration factor on the mixture of Ag paste and H3PO4 solution as a dopant paste for contact formation in silicon solar cells

Abstract

Screen printing dopant is a new technique to create emitter regions on solar cells. On top of the emitter region, there will be screen-printed metallic contacts that are commonly used silver as front contact. Both processes are performed in separate procedure which requires two different diffusion process involving a high-temperature process. Silver makes good ohmic contact on both light and heavily doped. A solution is proposed by applying a single step of screen printing and annealing process of Ag and phosphorus acid. Simultaneous annealing of Al, Ag, Ag/P screen-printed pastes form diodes with and without heavily doped phosphorous layers under Ag contacts on n-type and p-type silicon wafers by annealing at a constant temperature of 900℃ while varying annealing time from 10-40 seconds at a 10-second interval. The cross-section image of 5% and 10% of Ag/P was measured by using FESEM with EDX report has identified the presence of phosphorus in the Ag/P paste. Dark IV shows an ohmic contact for both p- and n-type. The ability to form the Ag/P paste in the screen-printing process makes it amenable to use as a self-dopant paste process in solar cells.