~20% Efficient Si PERC Solar Cell with Emitter Surface Passivated by H2S Reaction

Phosphorous $(\mathrm{n}^{+})$ diffused emitter surface was passivated by hydrogen sulfide (H2S) gas reaction and fabricated to small area (4 cm ² ) p-type passivated emitter and rear contact (PERC) Si solar cells using an industry standard screen printed metallization process. A promising implied open circuit voltage $(\text{iVoc})$ of 686 $\text{mV}$ was achieved with the emitter $(\mathrm{n}^{+})$ passivated by sulfur. A completed cell Voc of $\approx 645-650\text{mV}$ was recorded in light JV curves, and an efficiency of 19.93% was demonstrated. Degradation during the metal contact firing step was found, limiting cell performance. X-ray photoelectron spectroscopy (XPS) studies reveal an increase in sulfur at the surface after high temperature exposure, suggesting the diffusion of sulfur and/or thinning of the $\text{SiN}_{\mathrm{x}}$ surface passivation layer.