High Efficiency Rear Emitter Pert Cells on CZ and FZ N-Type Silicon Substrates

In this paper, we report energy conversion efficiencies of 20.8% from CZ and 22.7% from FZ n-type silicon substrates, by a rear emitter PERT (passivated emitter, rear totally-diffused) cell structure. Record efficiency of 22.7% and excellent open-circuit voltage of 706 mV have been demonstrated by these rear emitter cells on n-type FZ substrates. The comparable high efficiency from the CZ substrates also confirmed that high cell efficiencies can be achieved from these lower quality CZ silicon substrates. Since the CZ cell results came from the first batch of such CZ cells, it shows the minimum performance boundary for these CZ cells. Higher performance is expected from future experiments, due to very little difference in the experimental minority carrier lifetimes between CZ and FZ substrates.