Large-Area n-Type PERT Solar Cells Featuring Rear p + Emitter Passivated by ALD Al 2 O 3

We present large-area n-type PERT solar cells featuring a rear boron emitter passivated by a stack of ALD Al 2 O 3 and PECVD SiO x . After illustrating the technological and fundamental advantages of such a device architecture, we show that the Al 2 O 3 /SiO x stack employed to passivate the boron emitter is unaffected by the rear metallization processes and can suppress the Shockley–Read–Hall surface recombination current to values below 2 fA/cm 2 , provided that the Al 2 O 3 thickness is larger than 7 nm. Efficiencies of 21.5% on 156-mm commercial-grade Cz-Si substrates are demonstrated in this study, when the rear Al 2 O 3 /SiO x passivation is applied in combination with a homogeneous front-surface field (FSF). The passivation stack developed herein can sustain cell efficiencies in excess of 22% and $V_{{\rm oc}}$ above 685 mV when a selective FSF is implemented, despite the absence of passivated contacts. Finally, we demonstrate that such cells do not suffer from light-induced degradation.