Multicrystalline Silicon Solar Cells with Efficiencies Exceeding 20%

Float-zone (FZ) monocrystalline silicon is an excellent material to achieve high energy conversion efficiencies () as the bulk lifetime is typically only limited by intrinsic Auger recombination. Multicrystalline silicon (mc-Si), on the other hand, is predominantly limited by crystal defects and impurities. In this work, we compare monocrystalline FZ silicon with high-quality block-cast mc-Si using our adapted high-efficiency PERC (passivated emitter and rear cell) process. The open-circuit voltage (Voc) of a solar cell is the most relevant measure of the material quality. We achieve Voc values of up to 659 mV on high-quality mc-Si material grown in a high-purity crucible. Using the same process sequence, we obtain comparable Voc values for high-quality mc-Si and monocrystalline silicon. We achieve an energy conversion efficiency of = 20.0 % on a preselected 1 cm² area of a high-purity mc-Si wafer.