Interdigitated Back-Contacted Silicon Heterojunction Solar Cells With Improved Fill Factor and Efficiency

We compare recently reported results of efficient back-contacted amorphous/crystalline silicon heterojunction solar cells with fill factors up to 78.8% with calculated j-V characteristics that are 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.