Towards 90% Bifaciality for p-Type Cz-Si Solar Cells by Adaption of Industrial PERC Processes

We demonstrate a bifaciality of 88.0% for 6-inch bifacial p-type Cz-Si passivated emitter and rear cells (biPERC) and increase their rear side energy conversion efficiency to 18.0% by minor adaptions in the fabrication sequence. We utilize the "pPassDop" concept on the cells' rear side that applies an aluminum oxide and a boron-doped silicon nitride (SiNX: B) layer stack for simultaneous passivation and doping source. Laser doping forms the local p-doped back surface field regions for these biPERL solar cells. Screen-printed silver-aluminum metallization contacts these regions. We also demonstrate the compatibility of the laser doping approach with conventional (undoped) SiNX capping layer to fabricate biPERL devices with screen-printed contacts.