FIB-SEM tomography is used to reconstruct the carbon binder domain (CBD) of a LiCoO 2 battery cathode (3.9 µm 5 µm 2.3 µm) with contrast enhancement by ZnO infiltration via atomic layer deposition. We calculate the porosity inside the CBD (57.6%), the cluster-size distribution with a peak at 54 nm and the pore-size distribution with a peak at 64 nm. The tortuosities of the pore space (1.6-2.0) and the CBD (2.3-3.5) show a mild anisotropy, which is attributed to the fabrication process. A comparison to a modeled homogenous CBD reveals that clustering in the CBD decreases its electronic conductivity

In this paper, we present a method to quickly evaluate the long-term effects of copper-containing metal stack systems for silicon solar cell front–side metallization. Copper diffusion, which is detrimental for the solar cell performance, is accelerated by exposing the cell to thermal stress. In this paper, we suggest to quantify the degree of copper diffusion into the cell by the very fast Suns- VOC technique, measuring the pseudo fill factor (pFF). Using three or more different temperatures, and assuming a certain loss in pFF corresponds to a certain depth of diffusion, the effective activation energy for copper diffusion for a given system can be extracted from an Arrhenius plot of the measured data. An extrapolation into temperature regions typical for solar cell modules under outdoor conditions allows an estimation of the fill factor loss for any operation time and temperature. Compared to time- and cost-intensive methods such as transmission electron microscopy or secondary-ion mass spectrometry, this kind of investigation requires only sparse equipment and can typically be done in 1 week per stack system.

No abstract

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.

Our work deals with the creation of copper-containing stack systems for the front side metallization of silicon solar cells. In this contribution, we give an overview of different approaches from our labs. We have developed processes to apply nickel diffusion barriers onto seed layers and directly onto silicon with both electrolytic and electroless processes. These are reinforced by a light-induced copper plating process. On aerosol-printed seed layers, cell efficiencies equal to those of reference cells with advanced silver metallization have been achieved with a nickel/copper/tin stack system (16.8% on 5×5cm2 industrial Cz-material, 20.3% on FZ high-efficiency substrates, 2×2cm2). As the long term stability of the resulting cells is a critical factor, there is need for a method to characterize this aspect. We developed a thermally accelerated ageing procedure, mirroring the total copper diffusion during a typical cell life cycle. Solar cells with advanced metal stack systems have shown no significant decrease in performance during this thermal stress test