Efficiency Potential of p- and n-Type High Performance Multicrystalline Silicon

Seed-assisted growth of multicrystalline (mc) silicon ingots has led to a significant increase in mc silicon material quality (so called high performance multicrystalline silicon, “HPM Si”) and thus efficiencies of p-type mc silicon solar cells in the past years. Additionally, recent research revealed a high efficiency potential of n-type standard mc silicon due to its large tolerance to many metallic impurities. This suggests a high potential of n-type high performance mc silicon with a low density of dislocation clusters. In this study, the efficiency potential of p- and n-type high performance mc silicon, produced under identical conditions in the same laboratory crystallization furnace, is investigated after different high efficiency solar cell processing steps. The prediction of solar cell efficiencies by an “Efficiency limiting bulk recombination analysis” (ELBA) discloses a very high potential with material related losses of less than 1%abs. compared to the cell limit. In combination witha high efficiency cell concept featuring a full area passivated rear contact (TOPCon), efficiencies exceeding 20% on isotextured n-type HPM samples and close to 22% on samples with an improved texture are predicted. To support these predictions with results on actual devices, solar cells were fabricated. First results on cell level indicate high Voc and Jsc values in the range predicted by ELBA simulations and an efficiency of 19.3%.