Mai Yaohua

Self-formed point-contact PERC solar cells

In this paper, the Al2O3 film was prepared by sol-gel method (sol-gel-Al2O3) as the rear surface passivation layer of passivated emitter rear contact (PERC) solar cells. It was found that the Al2O3 passivation layer provided a self-formed local contact, i.e. the passivation layer existed in the bottom and the inclined plane instead of the top, of the pyramid. Thus, unlike the conversional PERC solar cells, no laser ablation is used in this PERC solar cells with sol-gel-Al2O3 passivation layer. The results show that this kind of self-formed point-contact technology has very good electrical contact characteristics. This effect leads to that this PERC cellslightly surpassesthe solar cell with the full back metal contact in the fill factor (FF), which is different from the conventional PERC cell with laser ablation. It was also found thatthe introduction of sol-gel-Al2O3 passivation layer can improve the infrared lightabsorptionin the cell. By measuring the reflection of the SiN x /Si/Al2O3/Al geometry, it was directly demonstrated thatsol-gel-Al2O3 passivation layer enhanced the internal reflectionin the cell. The open circuit voltage ( V oc) and short circuit current density ( J sc) of the cell were improved, and the conversion efficiency ( η ) finally increased by 1%.