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 Ω/sq) by rapid alloying of PV168 Ag paste. Excellent specific contact resistance (∼1 mΩ-cm²) in conjunction with high fill factor (FF) (0.775) were obtained on 100 Ω/sq emitters by a 900°C 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 Ω/sq cell showed a noticeable improvement of ∼0.5% in absolute efficiency over a conventional co-fired 45 Ω/sq emitter cell. Lighter doping in the 100 Ω/sq emitter cell resulted in better blue-response compared to the conventional cell, contributing to ∼1.3 mA/cm² improvement in short-circuit current. Improved surface passivation on 100 Ω/sq emitter cell resulted in additional 0.6 mA/cm² 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%.