Development of screen-printed silicon solar cells with high fill factors on 100 Ω/sq emitters

High-quality DuPont screen-printed Ag contacts were achieved on high sheet-resistance emitters (100 Ohm/sq) by rapid alloying of PV168 Ag paste. Excellent specific contact resistance (similar to 1 mOhm - cm(2)) in conjunction with high fill factor (FF) (0.775) were obtained on 100 Ohm/sq emitters by a 900 degreesC spike firing of the PV168 paste in a belt furnace. The combination of the alloying characteristics of the PV168 Ag paste and optimized single-step rapid low-thermal budget firing resulted in a cost-effective manufacturable process for high-efficiency Si solar cells. In addition, the co-fired 100 Ohm/sq cell showed a noticeable improvement of similar to0.5% in absolute efficiency over a conventional co-fired 45 Ohm/sq emitter cell. Lighter doping in the 100 Ohm/sq emitter cell resulted in better blue-response compared to the 2 conventional cell, contributing to similar to 1.3 mA/cm(2) improvement in short-circuit current. Improved surface passivation on 100 Ohm/sq emitter cell resulted in additional 0.6 mA/cm(2) increase in J(sc), 15-mV higher V-oc, and a 0.6% increase in absolute cell efficiency. Front grid design optimization resulted in a FF of 0.780, and a further improvement in cell efficiency to reach 17.4%. Index Terms-High sheet-resistance emitters, photovoltaic cells, screen-printed contacts, silicon.