Transferring the Record p-type Si POLO-IBC Cell Technology Towards an Industrial Level

We report on the transfer of our lab-type POLO
²
-IBC process with POLO contacts for both polarities towards an industrial level. Here we demonstrate a shortened cell fabrication process that uses p-type wafers and keeps the Al-back surface field of the PERC process but substitutes the phosphorous diffusion by a n-type poly-Si deposition. The resulting POLO-IBC process is similarly short as the PERC process. A high lifetime with the Cz material and highly selective POLO junctions require a reduce thermal budget and a reduced thickness of the interfacial oxide compared to our previous lab cells that used FZ silicon wafers. Our POLO-IBC cells have an efficiency potential of 24.5 % as deduced from simulations. We measure an efficiency of 21.8 % after finishing the first cell batch. For a cell from our second cell batch with improved passivation we measure an implied pseudo efficiency of 25.2 % before laser contact openings.