Loss analysis of back-contact back-junction thin-film monocrystalline silicon solar cells

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Layer selective laser ablation for local contacts to thin emitters

High efficiency solar cells require high generation and low recombination rates. High bulk lifetime, well passivated surfaces, and lowly doped thin emitters allow for low recombination rates. Thin passivated emitters should be contacted locally in order to avoid excessive contact recombination. This is common practice for front junction solar cells but is also advantageous for back junction cells. We analyze a novel layer selective laser ablation process. From a passivating stack composed of 70 nm silicon nitride that we deposit on top of 35 nm of amorphous silicon we selectively ablate the silicon nitride layer. Transmission electron microscopy investigations confirm the full ablation of the silicon nitride layer. After the ablation process, a 17 nm-thick amorphous silicon layer remains on the substrate. The crystalline silicon substrate shows no dislocations after the process. Evaporating aluminum on top of the locally ablated nitride layers forms local contacts of the aluminum to the silicon

Cracks in Solar Cell Metallization Leading to Module Power Loss under Mechanical Loads

AbstractWe investigate the mechanisms leading to electrically insulated cell parts in a photovoltaic module under mechanical load. For this we measure the resistances across a crack in a laminated solar cell during bending that is typical in the field. The cracks in the solar cell are detected with electroluminescence imaging. The resistance over the aluminum paste increases continuously by negligible 30 mΩ whereas the front finger resistance increases by 15.4 kΩ stepwise. This difference is the result of the higher ductility of the aluminum paste in comparison to the front finger metallization. We associate the steps in the front finger resistance measurement to breakage of single fingers with an equivalent circuit model. Furthermore we found that a silicon crack widths lower 2μm has no influence on the resistances. Crack widths higher than 7μm leads to a complete front finger interruption. We determine that the specific resistance of such a crack causes nearly 100% of the power loss, which is caused by a completely electrically insulating crack in a photovoltaic module

Opioidtherapie und ihre Auswirkung auf die Lebensqualität von Tumorschmerzpatienten : Eine prospektive Observationsstudie zu den Opioiden Morphin, Hydromorphon, Fentanyl und Buprenorphin

Es konnte kein signifikanter Unterschied in der Beeinträchtigung der Lebensqualität in den unterschiedlichen Kohorten der vier untersuchten Opioide festgestellt werden. Somit lässt sich eine generelle Empfehlung für die Verordnung eines der vier untersuchten Opioide in Hinblick auf eine bestmögliche Erhaltung der Lebensqualität von Tumorpatienten nach der hier durchgeführten Untersuchung nicht feststellen. Die Auswertung zeigt aber, dass im Hinblick auf den Einfluss auf die Lebensqualität der Patienten unter Umständen eine schwache Empfehlung für die Verabreichung von Hydromorphon ausgesprochen werden könnte, da die mit Hydromorphon behandelten Patienten bei drei von vier signifikanten Fragen jeweils die geringste Beeinträchtigung angaben. Zu beachten ist hier jedoch, dass lediglich bei 13,32 % der Fragen überhaupt ein signifikanter Unterschied in der Beeinträchtigung der Lebensqualität der Patienten abhängig von dem verordneten Opioid festgestellt werden konnte

A comparison of models to optimize Partial Rear Contact solar cells

The optimization of solar cells with localized rear contacts usually requires numerical simulation. Here we compare Sentaurus Device to a simpler Conductive Boundary (CoBo) simulator and to an approximate Geometric model. Optimization examples are given for devices with linear rear contacts in low and high injection conditions. The three modelling tools are in good agreement for high quality devices with negligible bulk and rear surface recombination. Discrepancies between the three models, generally small, are identified and explained

General simulation method for quantum-sensing systems

Quantum sensing encompasses highly promising techniques with diverse applications including noise-reduced imaging, super-resolution microscopy as well as imaging and spectroscopy in challenging spectral ranges. These detection schemes use biphoton correlations to surpass classical limits or transfer information to different spectral ranges. Theoretical analysis is mostly confined to idealized conditions. Therefore, theoretical predictions and experimental results for the performance of quantum-sensing systems often diverge. Here we present a general simulation method that includes experimental imperfections to bridge the gap between theory and experiment. We develop a theoretical approach and demonstrate the capabilities with the simulation of aligned and misaligned quantum-imaging experiments. The results recreate the characteristics of experimental data. We further use the simulation results to improve the obtained images in post-processing. As simulation method for general quantum-sensing systems, this work provides a first step towards powerful simulation tools for interactively exploring the design space and optimizing the experiment's characteristics.Comment: 19 pages, 8 figure