n-type PERT and PERL structures both offer a high efficiency potential. In this work we applied ion implantation for the realization of both the emitter and the BSF of highefficiency PERT and PERL structures and laser processes for local BSF formation showing efficiency benchmarks for those in principle industrially feasible technologies. For a fully ion implanted PERT solar cell we reached efficiencies up to 22.7%, showing that even at this high level no residual implantation damage is left and the V oc is limited by the profiles themselves. For the PERL structure we applied the PassDop process using two different passivation layer systems (based on SiC x and SiN x ). With this laser based process we were able to reach conversion efficiencies up to 23.2%, showing that the laser doping process is as efficient as a PERL rear side realized by photolithography. To prove the industrial feasibility of these high-efficiency solar cell concepts we applied Ni plating as front side emitter metallization on a PassDop solar cell featuring a boron implanted emitter. For this cell type we were able to reach an efficiency of 21.7% in a first prove of principle batch.

In this paper, first generation back-contact backjunction (BC-BJ) silicon solar cells with cell efficiencies well above η = 20% were fabricated. The process sequence is industrially feasible, requires only one high-temperature step (codiffusion), and relies only on industrially available pattering technologies. The silicon-doping is performed from pre-patterned solid diffusion sources, which allow for the precise adjustment of phosphorus-and boron-doping levels. Based on the investigated process technologies, BC-BJ solar cells with gap and without gap between adjacent n + -and p + -doped areas were processed. On the one hand, a strong reduction of the process effort is possible by omitting the gap regions. On the other hand, parasitic tunneling currents through the narrow space charge region may occur. Hence, deep doped areas were realized to avoid tunneling currents in gap-free BC-BJ cells. This paper finishes with a detailed characterization of the manufactured cells including important cell measurements like I-V, SunsVOC, quantum efficiency, and an analysis of the cell specific fill factor losses.

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Industrial tunnel oxide and passivated contact (i-TOPCon) solar cells were metallized at Fraunhofer ISE using ultrashort pulse laser ablation of the passivation layers for the subsequent Ni/Cu/Ag plating process. The solar cells feature a tunnel SiO x and n-type doped polysilicon layer covered by a SiN x at the rear side, whereas the front side is made of a boron emitter passivated with a AlO x /SiN x stack. The reference i-TOPCon solar cells screen-printed at the supplier reach an efficiency of 23.46% measured by Fraunhofer ISE CalLab. The impact of the laser process on the implied open circuit voltage (iV oc ) is characterized showing minor impact on the TOPCon side, while the emitter side reveals an increased iV oc loss due to laser damage. Loss analysis by simulating the plated solar cells points out the benefit of reducing the laser contact opening (LCO) area in terms of shading and contact recombination.Optimization of laser ablation and hydrofluoric acid (HF) pretreatment process result in V oc > 700 mV and FF > 82% leading to a mean efficiency 23.6% measured in-house and a champion efficiency of 23.84% measured at Fraunhofer ISE CalLab thus outperforming the references by 0.4% abs .

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