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  Haschke, J.; Mingirulli, N.; Gogolin, R.; Ferré, R.; Schulze, T.F.; Düsterhöft, J.; Harder, N.-P.; Korte, L.: Interdigitated Back-Contacted Silicon Heterojunction Solar Cells with Improved Fill Factor and Efficiency. IEEE Journal of Photovoltaics 1 (2011), p. 130-134

Abstract:
We compare recently reported results of efficient back-contacted amorphous/crystalline silicon heterojunction solar cells (IBC-SHJ) with fill factors up to 78.8 % with calculated j-V-characteristics, derived from an area weighted summation of recombination currents taken from lifetime measurements. We compare solar cell structures with and without an intrinsic buffer layer beneath the p-type amorphous silicon emitter. We find that the inclusion of the buffer layer reduces the fill-factor potential by changing the ideality of the recombination current. However, analyzing the series resistance by illumination dependent j-V-measurements we find that the major loss mechanism of the fill-factor is the limitation of the charge carrier transport.