Towards 20% efficient n-type silicon solar cells with screen-printed aluminium-alloyed rear emitter
We present n-type silicon solar cells featuring an effectively passivated full-area screen-printed aluminium-alloyed rear emitter. Two different passivation stacks for Al-p+ emitters are investigated: The first one consists of a plasma-enhanced-chemical-vapour-deposited amorphous silicon film covered by a plasma silicon oxide layer, the second one of a plasma-assisted atomic-layer-deposited aluminium oxide also covered by a plasma silicon oxide. For our a-Si/SiOx-passivated back junction n+np+ solar cells (4 cm2) we achieve an increase in the open-circuit voltage of 15â 20 mV compared to the non-passivated emitter cells, for our Al2O3/SiOx-passivated cells the shift amounts to 25â 30 mV, resulting in Voc values up to 655 mV. This leads to record-high efficiencies for solar cells with aluminium-doped emitter of 19.5 % and 20.1 %, respectively, on n-type phosphorus-doped 10 Îcm float-zone silicon material.