Latest Results in Screen-Printed IBC-ZEBRA Solar Cells

We developed a low-cost and high-efficiency IBC solar cells process ready to be transferred to industrial mass production. This so-called ZEBRA technology is lito-process free and it requires only one mask for the gas-phase diffusions. In this paper, we review the latest optimizations of the ZEBRA process in the attempt to achieve high open-circuit voltage (Voc) reducing the metallization losses and improving the passivation of phosphorous and boron doped regions. By a significant reduction of the contact area of the devices, we demonstrate a way to make screen printed Ag point-contacts feasible and to improve the efficiency of the ZEBRA cells of more than 22.3% and a Voc of 668 mV. Moreover we introduce a potential industry scenario in which we forecast ZEBRA cells efficiencies up to 22.8 % in mass production. Additionally, update CoO calculations are presented to demonstrate the economic feasibility of the ZEBRA process. At last, we introduce the new generation of ZEBRA cell (Gen2) as the latest process development. The J
_0,e
and J
_0,met
of the p
⁺
and n
⁺
regions are reduced by lowering the surface concentration of the doping profiles, meanwhile, the fine tuning of the contacts formation allow for a RC <; 2.5 mΩ.cm
²
. Excellent surface passivation obtained with oxide/SiNx stack layers with implied Voc of 710 mV and Joe=14 fA/cm
²
on symmetrically diffused boron emitter. Finally, solar cells with energy conversion efficiencies up to 23.2% were fabricated.