HIGH EFFICIENT N-TYPE BACK-JUNCTION BACK-CONTACT SILICON SOLAR CELLS WITH SCREEN-PRINTED AL-ALLOYED EMITTER

摘要

N-type back-junction back-contact (BJ-BC) silicon solar cells have been successfully introduced in and are being investigated by several research groups. For such n-type bulk Si solar cells, the formation of the p~+ emitter is still an issue. In recent years, people have shown excellent results on n-type front contact rear junction cells with a screen-printed Al-alloyed emitter. In this work, we demonstrate the use of such emitters on n-type BJ-BC silicon solar cells. Different pitch sizes and emitter fractions have been studied. Clear trends of the short-circuit current densities have been observed. Different front surface field (FSF) profiles were applied to our cells. The shallower FSF with a lower surface doping concentration results in lower front surface recombination, which results in the best cell performance. Efficiencies of 19.1% under 1 Sun on BJ-BC solar cells with an aperture area of 2 cm × 2 cm have been achieved on n-type FZ and CZ silicon wafers. Better quality emitter with more effective cleaning process steps and passivation layers have been developed, to result in a further increase in cell efficiency in the future work.