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State-of-the-art electrode materials for all-vanadium redox flow batteries are based on carbon. Unfortunately, the impact of the carbon structure, i.e., microstructure/crystallinity, surface functional groups, and porosity/morphology/surface area, on the electrochemical performance is still unclear. This is due to the fact that usually several structural characteristics are varied due to synthesis or post-treatment procedures at the same time. Therefore, this paper shows systematically how microstructure, porosity, and surface functional groups vary with carbonization and graphitization temperature (ranging from 700 to 1500 °C) for a mesoporous N-doped carbon (MPNC). Changes in the material's structure (e.g., morphology, porosity, crystal structure, surface functionalization), determined by scanning and transmission electron microscopy, X-ray diffraction (pair distribution function analysis), X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and N2 sorption measurements, are correlated to changes in wettability, conductivity, and electrochemical kinetics, investigated by H2O sorption measurements, cyclic voltammetry, and electrochemical impedance spectroscopy in the VO2+ electrolyte, respectively. We found that the kinetics of the VO2+/VO2+ reaction increases with an increase in sp2-C content and therefore an increase in crystallite size and conductivity of the mesoporous N-doped carbon. Nevertheless, the largest current for the VO2+/VO2+ reaction for the same amount of carbon during cyclic voltammetry is observed for the MPNC carbonized at an intermediate temperature, 1000 °C, as a result of its larger wettability and thus available surface area compared to the MPNC carbonized at 1500 °C.

29th European Photovoltaic Solar Energy Conference and Exhibition; 1763-1769, We present a study of the degradation of thin-film CIGS material in the vicinity of P2 phase-transformation type of laser scribes. They comprised optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, photoluminescence and Raman spectroscopy. While the optical and electron microscopy measurements have shown a clear change of the morphological properties of CIGS including removal, melting and dislocation of material from the area scribed by the laser, the X-ray analysis revealed an accumulation of O, Zn, Ga, and Cu elements in the melted phase and an evaporation of more volatile In atoms from the region of visually changed CIGS. At the same time Raman and photoluminescence measurements have shown substantial alteration of semiconductor material properties, i.e. of the crystallinity and the bandgap energy even far beyond of this region. More precisely, the amplitudes of the A1 and B2,E Raman peaks were found to increase continuously with increasing distance from the P2 scribes, reaching the distances of approximately three times the 3 diameter of the beam. A similar tendency was also observed for photoluminescence signals, that additionally revealed a systematic shift of the bandgap energy in CIGS as estimated from the maximum of the emission spectrum. Our results indicate that the phase-transformation scribing generates changes in thin-film CIGS material far beyond the heat affected zone. As such they can help to decide on optimal spacing between P1-P3 scribes and thus reduce a "dead area" of thin-film CIGS solar cells.

28th European Photovoltaic Solar Energy Conference and Exhibition; 2691-2693, We present results on 1D-grating textures in ZnO:Al layers fabricated using direct pulsed laser interference texturing. A typical laser written grating texture showed a haze value of 9% at 700 nm. The total transmission of the film was not lowered compared to the film before texturing, while the sheet resistance increased moderately by 15%. A-Si:H/μc-Si:H solar cells with laser textured ZnO:Al front contact layers so far reach an efficiency of 10 % and current densities of 11.1 mA/cm², and 11.2 mA/cm² for top and bottom cell, respectively. This is an increase of 16% for the bottom cell as compared to flat ZnO:Al. This texturing method allows to write textures also in ZnO:Al films that cannot be texture etched in HCl. It can be improved further by using 2D periodic patterns and by optimizing the groove period and depth, and may be applicable also to other solar cell technologies.

In this work we present results of different strategies of how CIGSe solar cells can be laser scribed focusing on P2 and P3. Therefore a laser source with a wavelength of 532 nm and pulse duration of 13 ns, as well as a laser, with pulse durations of 10 ps for both wavelengths of 532 nm and 1064 nm are used. The ablation mechanisms and the results ablation process behaviors due to different wavelengths and pulse durations are studied. Different parameters like process speed, scribe quality and solar cell performance are discussed. Successful laser patterning of all layers is demonstrated on a minimodule reaching 10 efficiency which is slightly better than the needle scribed reference

28th European Photovoltaic Solar Energy Conference and Exhibition; 2302-2306, In this work we present results of different strategies of how CIGSe solar cells can be laser scribed focusing on P2 and P3. Therefore a laser source with a wavelength of 532 nm and pulse duration of 13 ns, as well as a laser, with pulse durations of 10 ps for both wavelengths of 532 nm and 1064 nm are used. The ablation mechanisms and the results ablation process (behaviors) due to different wavelengths and pulse durations are studied. Different parameters like process speed, scribe quality and solar cell performance are discussed. Successful laser patterning of all layers is demonstrated on a minimodule reaching 10% efficiency which is slightly better than the needle scribed reference.

26th European Photovoltaic Solar Energy Conference and Exhibition; 2943-2946, Structuring of thin-film photovoltaic modules requires basic knowledge of the laser – thin-film interaction in order to adapt the accessible laser parameters, like wavelength, power, repetition rate and scribing speed whilst taking into account the specific material properties of the layer. We have studied the nanosecond laserablation behavior of corresponding layers (i) of silicon based thin-film solar cells with a-Si/μc-Si tandem absorber type and (ii) of back contact and absorber layer of CIGSe solar cells. The respective ablation threshold fluences were determined as integrative parameters describing the specific laser – material interaction. For the threshold determination we used two different methods and developed a new analytical approach taking into account scribing through the glass substrate as it is preferred for most structuring processes. This was done by analyzing the thin film ablation results by means of optical microscopy, profilometry, scanning electron microscopy (SEM). Moreover, we determined the incubation coefficient of the regarded material layers which allows us to predict quantitatively the influence of the spot overlap on the scribing threshold.

26th European Photovoltaic Solar Energy Conference and Exhibition; 2540-2543, Manufacturing of CIGSe thin film solar modules involves typically one laser structuring step (P1) and two mechanical structuring steps (P2 and P3) for serial interconnection. In our approach, complete laser structuring is successfully demonstrated by application of short nanosecond laser pulses (

The California Verbal Learning Test (CVLT) is recognized as a standard clinical tool for assessing episodic memory difficulties in multiple sclerosis (MS), but its neural correlates have not yet been examined in detail in this patient population. We combined neuropsychological examination and diffusion tensor imaging (DTI) analysis in a group of MS patients (N = 50) and demographically matched healthy participants (N = 20). We investigated the degree of impairment of the uncinate fascicle (UF), the superior longitudinal fascicle (SLF), the fornix (FX) and the cingulum (CG). The patients were impaired on all CVLT parameters and the DTI parameters correlated moderately with disease-related variables. Regression analyses in the complete study sample showed that CVLT learning scores correlated with impairment of the right UF. This association reached marginal significance in the patient sample. In contrast to other studies claiming retrieval deficits, our results suggest that encoding and consolidation deficits may play a major role in verbal memory impairments in MS. The findings also provide evidence for an association between degree of myelination of prefrontal fibre pathways and encoding efficiency. Finally, DTI-derived measurements appear to reflect disease progression in MS. The results are discussed in light of functional MRI studies investigating compensatory brain activity during cognitive processing in MS.

Based on amino acid based pair-potentials and intermolecular energies we calculate score distributions for protein-protein complexes that exist in nature and those which do not exist. The distributions of the two groups are then found to be different in maximum and in shape. This opens the possibility to discriminate between complexes that exist and those which do not.