Loss Analysis of n-Type Passivated Emitter Rear Totally Diffused Back-Junction Silicon Solar Cells with Efficiencies up to 21.2%

In this work, we present screen-printed n-type passivated emitter rear totally diffused (n-PERT) back-junction (BJ) silicon solar cells with efficiencies up to 21.2% on total area of 239 cm
²
. The process sequence is based on that of p-type passivated emitter and rear cells (p-PERC), adding only a boron diffusion at the beginning. We reduce the recombination at the homogeneous phosphorus-doped front surface field by a wet-chemical etch-back of 10-20 nm and apply an advanced five-busbar layout on the front side to increase the energy conversion efficiency. We simulate the performance of the n-PERT BJ solar cell using the conductive boundary model and perform a synergistic efficiency gain analysis to identify the main limitations of our n-PERT BJ solar cells. We observe the biggest gain of 0.72% absolute after eliminating recombination at the P-doped front surface field and find that reducing recombination in general is most important for further improving our n-PERT BJ solar cells.