Laserschweißen von Siliziumfolien zur Herstellung von Dünnschicht-Solarzellen

Thin-film solar module manufacturing is one of the most promising recent developments in photovoltaic research and has the potential to reduce production costs. As the necessity for competitive prices on the world market increases and manufacturers endeavor to bring down the cost of solar modules, thin-film technology is becoming more and more attractive. In this work a special technique was investigated which makes solar cell manufacturing more compatible with an industrial roll-to-roll process. This technique allows the creation of the first monocrystalline band substrate by welding several monocrystalline silicon wafers together, so that the size restriction of float-zone grown wafers can be overcome. Currently the size is 8 inches in diameter. Float-zone grown material is well suited as feedstock for high efficiency solar cells and it has also been very intensively studied in the past. This makes it the perfect feedstock material for thin-film solar modules. Unfortunately this material is quite expensive and therefore it should only serve as feedstock to generate the band substrate. After this step the necessary silicon layers to produce solar cells are grown epitaxially on top of the band substrate using chemical vapor deposition. To produce solar cells a silicon layer is separated from the band substrate using a layer transfer process. Subsequently the band substrate can be repeatedly reused to produce an infinite amount of silicon layers without requiring any silicon ingot feedstock. The linchpin for this technique is the welding step from single wafers to a band substrate. Thus, this work focuses on the investigation of the welding process. Welded samples were analyzed using micro-Raman and electron backscatter diffraction (EBSD). Moreover, the achievement of solar cells on top of 50 µm thick silicon foils and welded silicon foils are reported.Die Produktion von Dünnschicht-Solarmodulen ist eine der vielversprechendsten Entwicklungen in der Photovoltaik in der näheren Vergangenheit, weil diese Technik geringe Produktionskosten verspricht. Wegen der Notwendigkeit von wettbewerbsfähigen Preisen an den Weltmärkten und dem Bemühen der Hersteller die Produktionskosten zu senken gerät die Dünnschicht-Technik immer mehr in den Fokus. In dieser Arbeit wird eine spezielle Technik untersucht, die die Herstellung von Solarzellen weiter an ein industrielles Rolle-zu–Rolle-Verfahren annähern soll. Diese Technik erlaubt es, monokristalline Siliziumwafer miteinander zu dem ersten monokristallinen Bandsubstrat zu verschweißen. Dadurch kann die Größenrestriktion der Produktion von im Zonenschmelzverfahren hergestellten einkristallinen Silizium-Ingots überwunden werden, die momentan einen Durchmesser von 8 Zoll haben. Da im Zonenschmelzverfahren gewonnenes Silizium als Ausgangsmaterial für Hochleistungssolarzellen ideal ist und auch schon intensiv untersucht wurde, ist es der perfekte Ausgangspunkt für Dünnschicht-Solarmodule. Allerdings ist der hohe Preis für dieses Material ein Problem. Darum soll das hochwertige und teure Silizium nur für die Herstellung des Ausgangsbandsubstrates verwendet werden. Danach soll mittels chemischer Gasphasenabscheidung eine Epitaxie-Schicht auf dem Band gewachsen werden und diese gewachsene Schicht mittels Transferprozess vom Ausgangsband getrennt werden, um damit Solarzellen herzustellen. Das Bandsubstrat wird wiederverwendet um eine endlose Anzahl von Siliziumschichten zu produzieren ohne die Notwendigkeit von Silizium-Ingots als Ausgangmaterial. Für dieses Verfahren ist das Schweißverfahren der Dreh- und Angelpunkt, daher wurde in dieser Arbeit der Fokus auf das Charakterisieren der Verschweißung gelegt. Diese wurden mit Hilfe von Mikro-Raman und Electron backscatter diffraction (EBSD) untersucht. Außerdem wurden erfolgreich Solarzellen auf 50 µm dünnen Siliziumfolien sowie Solarzellen auf verschweißten Siliziumfolien hergestellt

Numerical and Experimental Investigation of Controlled Weld Pool Displacement by Electromagnetic Forces for Joining Dissimilar Materials

In order to reduce CO2 emissions, an increasing interest in lightweight construction exists in the automotive industry, especially the multi-material-design approach. The main construction materials here are steels and aluminium alloys. Due to their different physical material properties and limited mutual solubility, these two materials cannot be joined thermally without difficulty. This paper presents a new joining approach for dissimilar materials. It uses electromagnetic displacement of a laser-generated melt pool to produce overlap joints between 1 mm steel (1.0330) and 2 mm aluminium alloy (EN AW 5754). Contactless induced Lorentz forces are generated by an alternating current (AC) magnet system. The controlled displacement of the aluminium alloy melt into the hole of the overlying steel sheet is investigated through numerical and experimental studies. The numerical results are compared with cross sections and thermocouple measurements. For the first time, it is possible to achieve a reproducible controlled melt pool displacement on thin sheets to produce overlap joints between dissimilar materials

Host Genetic Background Strongly Influences the Response to Influenza A Virus Infections

The genetic make-up of the host has a major influence on its response to combat pathogens. For influenza A virus, several single gene mutations have been described which contribute to survival, the immune response and clearance of the pathogen by the host organism. Here, we have studied the influence of the genetic background to influenza A H1N1 (PR8) and H7N7 (SC35M) viruses. The seven inbred laboratory strains of mice analyzed exhibited different weight loss kinetics and survival rates after infection with PR8. Two strains in particular, DBA/2J and A/J, showed very high susceptibility to viral infections compared to all other strains. The LD50 to the influenza virus PR8 in DBA/2J mice was more than 1000-fold lower than in C57BL/6J mice. High susceptibility in DBA/2J mice was also observed after infection with influenza strain SC35M. In addition, infected DBA/2J mice showed a higher viral load in their lungs, elevated expression of cytokines and chemokines, and a more severe and extended lung pathology compared to infected C57BL/6J mice. These findings indicate a major contribution of the genetic background of the host to influenza A virus infections. The overall response in highly susceptible DBA/2J mice resembled the pathology described for infections with the highly virulent influenza H1N1-1918 and newly emerged H5N1 viruses

Tip of the Iceberg: Assessing the Global Socioeconomic Costs of Alzheimer's Disease and Related Dementias and Strategic Implications for Stakeholders

While it is generally understood that Alzheimer's disease (AD) and related dementias (ADRD) is one of the costliest diseases to society, there is widespread concern that researchers and policymakers are not comprehensively capturing and describing the full scope and magnitude of the socioeconomic burden of ADRD. This review aimed to 1) catalogue the different types of AD-related socioeconomic costs described in the literature; 2) assess the challenges and gaps of existing approaches to measuring these costs; and 3) analyze and discuss the implications for stakeholders including policymakers, healthcare systems, associations, advocacy groups, clinicians, and researchers looking to improve the ability to generate reliable data that can guide evidence-based decision making. A centrally emergent theme from this review is that it is challenging to gauge the true value of policies, programs, or interventions in the ADRD arena given the long-term, progressive nature of the disease, its insidious socioeconomic impact beyond the patient and the formal healthcare system, and the complexities and current deficiencies (in measures and real-world data) in accurately calculating the full costs to society. There is therefore an urgent need for all stakeholders to establish a common understanding of the challenges in evaluating the full cost of ADRD and define approaches that allow us to measure these costs more accurately, with a view to prioritizing evidence-based solutions to mitigate this looming public health crisis.This article is freely available via Open Access. Click on the Publisher URL to access it via the publisher's site.This work was partially sponsored by F. Hoffman La Roche Ltd (see below). We would like to thank Jean Georges (Executive Director Alzheimer Europe) for his suggestions and feedback on early drafts of this manuscript. Shift Health consults with organizations across the health and life sciences sector, including F. Hoffman La Roche Ltd. Authors from Shift Health (REW, CPK, YEH, RD) were employed under contract with Hoffman-La Roche Ltd. for the purposes of this work. Authors not employed by Shift Health (CB, ARE, MK, JLM, MN, and AA) did not receive support or remuneration related to this work. Authors’ disclosures available online (https://www.j-alz.com/manuscript-disclosures/19-0426)published version, accepted version, submitted versio