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P-176: HYPOLED - High-Performance OLED Microdisplays for Mobile Multimedia HMD and Projection Applications

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SID Symposium Digest of Technical Papers 2012年第1期41卷

作者： Michael Scholles Uwe Vogel Ian Underwood Gunther Notni Christian Zilstorff Klaus Meerholz Gunther Haas Fraunhofer Institute for Photonic Microsystems Dresden Germany Institute of Integrated Systems University of Edinburgh Edinburgh United Kingdom Fraunhofer Institute for Applied Optics and Precision Engineering Jena Germany Mobintech A/S Farum Denmark Dept. of Chemistry Universität zu Köln Köln Germany Microoled S.A.R.L. Grenoble France

The HYPOLED project, partly funded by the European Commission, started in 2008. Its goal is to develop OLED Microdisplays for Mobile Multimedia HMD and Projection Applications. This contribution describes the objectives and present specifications for devices, the personal display and micro- projection unit as well as intermediate results.

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Revealing fundamentals of charge extraction in photovoltaic devices through potentiostatic photoluminescence imaging

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arXiv 2021年

作者： Wagner, Lukas Schygulla, Patrick Herterich, Jan Philipp Elshamy, Mohamed Bogachuk, Dmitry Zouhair, Salma Mastroianni, Simone Würfel, Uli Liu, Yuhang Zakeeruddin, Shaik M. Grätzel, Michael Hinsch, Andreas Glunz, Stefan W. Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstraße 2 Freiburg79110 Germany Laboratory for Photovoltaic Energy Conversion University of Freiburg Emmy-Noether-Straße 2 Freiburg79110 Germany Freiburg Materials Research Center FMF University of Freiburg Stefan-Meier-Straße 21 Freiburg79104 Germany Abdelmalek Essaadi University FSTT Thin Films & Nanomaterials Lab Tangier90000 Morocco Department of Chemistry and Chemical Engineering École Polytechnique Fédérale de Lausanne LausanneCH-1015 Switzerland

The photocurrent density-voltage (J(V)) curve is the fundamental characteristic to assess optoelectronic devices, in particular solar cells. However, it only yields information on the performance integrated over the entire active device area. Here, a method to determine a spatially resolved photocurrent image by voltage-dependent photoluminescence microscopy is derived from basic principles. The opportunities and limitations of the approach are studied by the investigation of III-V and perovskite solar cells. This approach allows the real-time assessment of the microscopically resolved local J(V) curve, the steady-state Jsc, as well as transient effects. In addition, the measurement contains information on local charge extraction and interfacial recombination. This facilitates the identification of regions of non-ideal charge extraction in the solar cells and enables to link these to the processing conditions. The proposed technique highlights that, combined with potentiostatic measurements, luminescence microscopy turns out to be a powerful tool for the assessment of performance losses and the improvement of solar cells. © 2021, CC BY.

关键词： Perovskite solar cells

Solving the 3-SAT problem using network-based biocomputation

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arXiv 2022年

作者： Zhu, Jingyuan Salhotra, Aseem Meinecke, Christoph Robert Surendiran, Pradheebha Lyttleton, Roman Reuter, Danny Kugler, Hillel Diez, Stefan Månsson, Alf Linke, Heiner Korten, Till NanoLund Lund University Box 118 Lund22100 Sweden Solid State Physics Lund University Box 118 Lund22100 Sweden Department of Chemistry and Biomedical Sciences Linnaeus University Kalmar391 82 Sweden Center for Microtechnologies Technische Universität Chemnitz Chemnitz09126 Germany Fraunhofer Institute for Electronic Nano Systems ENAS Chemnitz Germany Faculty of Engineering Bar-Ilan University Ramat Gan Israel B CUBE - Center for Molecular Bioengineering Technische Universität Dresden Dresden01307 Germany

The 3-Satisfiability Problem (3-SAT) is a demanding combinatorial problem, of central importance among the non-deterministic polynomial (NP) complete problems, with applications in circuit design, artificial intelligence and logistics. Even with optimized algorithms, the solution space that needs to be explored grows exponentially with increasing size of 3-SAT instances. Thus, large 3-SAT instances require excessive amounts of energy to solve with serial electronic computers. Network-based biocomputation (NBC) is a multidisciplinary parallel computation approach with drastically reduced energy consumption. NBC uses biomolecular motors to propel cytoskeletal filaments through nanofabricated networks that encode the mathematical problems. By stochastically exploring possible paths through the networks, the cytoskeletal filaments find possible solutions to the encoded problem instance. Here we first report a novel algorithm that converts 3-SAT into NBC-compatible network format. We demonstrate that this algorithm works in practice, by experimentally solving four small 3-SAT instances (with up to 3 variables and 5 clauses) using the actin-myosin biomolecular motor system. This is a key step towards the broad general applicability of NBC because polynomial conversions to 3-SAT exist for a wide set of important NP-complete problems. © 2022, CC BY-NC-ND.

关键词： Polynomials

Electrochemical impedance spectroscopy beyond linearity and stationarity - a critical review

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arXiv 2023年

作者： Hallemans, Noël Howey, David Battistel, Alberto Saniee, Nessa Fereshteh Scarpioni, Federico Wouters, Benny La Mantia, Fabio Hubin, Annick Widanage, Widanalage Dhammika Lataire, John Research Group Fundamental Electricity and Instrumentation Vrije Universiteit Brussel Pleinlaan 2 Brussels1050 Belgium WMG University of Warwick Coventry7AL CV4 United Kingdom Battery Intelligence Lab Department of Engineering University of Oxford OX1 3PJ United Kingdom The Faraday Institution Quad One Harwell Science and Innovation Campus Didcot United Kingdom Institute of Technical Medicine Furtwangen University Jakob-Kienzle-Strasse 17 Villingen-Schwenningen78054 Germany Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM Wiener Strasse 12 Bremen28359 Germany Research Group Electrochemical and Surface Engineering Vrije Universiteit Brussel Pleinlaan 2 Brussels1050 Belgium Energy Storage and Energy Conversion Systems Bremen University Wiener Strasse 12 Bremen28359 Germany

Electrochemical impedance spectroscopy (EIS) is a widely used experimental technique for characterising materials and electrode reactions by observing their frequency-dependent impedance. Classical EIS measurements require the electrochemical process to behave as a linear time-invariant system. However, electrochemical processes do not naturally satisfy this assumption: the relation between voltage and current is inherently nonlinear and evolves over time. Examples include the corrosion of metal substrates and the cycling of Li-ion batteries. As such, classical EIS only offers models linearised at specific operating points. During the last decade, solutions were developed for estimating nonlinear and time-varying impedances, contributing to more general models. In this paper, we review the concept of impedance beyond linearity and stationarity, and detail different methods to estimate this from measured current and voltage data, with emphasis on frequency domain approaches using multisine excitation. In addition to a mathematical discussion, we measure and provide examples demonstrating impedance estimation for a Li-ion battery, beyond linearity and stationarity, both while resting and while charging. © 2023, CC BY.

关键词： Ions

Transport resistance dominates the fill factor losses in record organic solar cells

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arXiv 2024年

作者： Wang, Chen MacKenzie, Roderick C.I. Würfel, Uli Neher, Dieter Kirchartz, Thomas Deibel, Carsten Saladina, Maria Institut für Physik Technische Universität Chemnitz Chemnitz09126 Germany Department of Engineering Durham University Lower Mount Joy South Road DurhamDH1 3LE United Kingdom Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstr. 2 Freiburg79110 Germany Freiburg Materials Research Center FMF University of Freiburg Stefan-Meier-Str. 21 Freiburg79104 Germany Institute of Physics and Astronomy University of Potsdam Karl-Liebknecht-Str.24-25 Potsdam-GolmD-14476 Germany IMD-3 Photovoltaik Forschungszentrum Jülich Jülich52425 Germany Faculty of Engineering CENIDE University of Duisburg-Essen Carl-Benz-Str. 199 Duisburg47057 Germany

Organic photovoltaics are a promising solar cell technology well-suited to mass production using roll-to-roll processes. The efficiency of lab-scale solar cells has exceeded 20% and considerable attention is currently being given to understanding and minimising the remaining loss mechanisms preventing higher efficiencies. While recent efficiency improvements are partly owed to reducing non-radiative recombination losses at open-circuit, the low fill factor due to a significant transport resistance is becoming the Achilles heel of organic photovoltaics. The term transport resistance refers to a voltage and light intensity dependent charge collection loss in low-mobility materials. In this Perspective, we demonstrate that even the highest efficiency organic solar cells reported to-date have significant performance losses that can be attributed to transport resistance and that lead to high fill factor losses. We provide a closer look at the transport resistance and the material properties influencing it. We describe how to experimentally characterise and quantify the transport resistance by providing easy to follow instructions. Furthermore, the causes and theory behind transport resistance are detailed. In particular, we integrate the relevant figures of merit and different viewpoints on the transport resistance. Finally, we outline strategies that can be followed to minimise these charge collection losses in future solar cells. Copyright © 2024, The Authors. All rights reserved.

关键词： Organic solar cells

Identification of the LeTID defect formation as a hydrogen-related dissociation process

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AIP Conference Proceedings 2022年第1期2487卷

作者： Benjamin Hammann Lazhar Rachdi Wolfram Kwapil Florian Schindler Martin C. Schubert 1Fraunhofer Institute for Solar Energy Systems (ISE) Heidenhofstraße 2 79110 Freiburg Germany 2Laboratory for Photovoltaic Energy Conversion Department of Sustainable Systems Engineering (INATECH) University of Freiburg Emmy-Noether-Str. 2 79110 Freiburg Germany

We investigate possible correlations between the temporal evolution of Light and elevated Temperature Induced Degradation (LeTID) and of boron-hydrogen pairs. For this, samples were treated under dark annealing conditions at 160°C and the formation and annihilation of the LeTID defect and the formation of BH-pairs were studied simultaneously. Simulations were used to accompany the experiment. A linear correlation between the formation of the LeTID defect formation with the BH-pair formation was found, while no correlation was found for the annihilation of the LeTID defect and the degradation of surface passivation with the reactions revolving around BH-pairs. This correlation can be explained by assuming the LeTID defect formation to be a hydrogen-related dissociation process: Hydrogen dissociates from the LeTID precursor, binds to boron and the remains of the LeTID precursor are a recombination active defect responsible for LeTID. This assumption leads to a good agreement between simulation and experimental results.

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Investigation of LeTID where we can control it – Application of FZ silicon for defect studies

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AIP Conference Proceedings 2019年第1期2147卷

作者： Tim Niewelt Regina Post Florian Schindler Wolfram Kwapil Martin C. Schubert 1Laboratory for Photovoltaic Energy Conversion Department of Sustainable Systems Engineering (INATECH) University of Freiburg Emmy-Noether-Str. 2 79110 Freiburg Germany 2Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstraße 2 79110 Freiburg Germany

In this work we present results of a series of experiments to investigate the origin of the defects causing light and elevated temperature induced degradation (LeTID). It has been demonstrated that LeTID effects can be observed even in high purity monocrystalline silicon. The experiments are therefore performed on float-zone silicon and feature a variety of process schemes to test important hypotheses on LeTID and reproduce them under more defined conditions. Different surface passivation schemes based on aluminium oxide layers are combined with a designated hydrogenation treatment and subjected to different thermal processes on both p- and n-type wafers. The results on p-type wafers confirm several previous observations concerning, e.g., the influence of silicon nitride layers and the firing peak temperature. However, we do not observe a crucial influence of the specific firing temperature profile in the experiment. The investigated n-type wafers do not feature a typical LeTID behaviour but appear to be affected by the LeTID defect nonetheless. Firstly, we observe an improvement of the effective lifetime under LeTID testing conditions that is driven by an improvement of the bulk lifetime. Secondly, identical pattern are observed in lifetime images of n-type wafers directly after firing and of p-type wafers in the degraded state. These findings strongly indicate that LeTID defects can be present in the initial state of n-type wafers after firing.

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Erratum zu: A multi-method investigation of the permeability structure of brittle fault zones with ductile precursors in crystalline rock

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Grundwasser 2024年第2期30卷 173-173页

作者： Osten, Julian Schaber, Tom Gaus, Garri Hamdi, Pooya Amann, Florian Achtziger-Zupančič, Peter Department of Engineering Geology and Hydrogeology RWTH Aachen University Aachen Deutschland Institute for Geology and Geochemistry of Petroleum and Coal RWTH Aachen University Aachen Deutschland Fraunhofer Research Institution for Energy Infrastructures and Geothermal Systems IEG Aachen Deutschland

Model-based setup assistant for progressive tools

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AIP Conference Proceedings 2018年第1期1960卷

作者： Robert Springer Manuel Gräler Werner Homberg Christian Henke Ansgar Trächtler 1Chair of Forming and Machining Technology Faculty of Mechanical Engineering Warburger Straße 100 33098 Paderborn Germany 2Fraunhofer Institute for Mechatronic Systems Design IEM Zukunftsmeile 1 33098 Paderborn Germany

In the field of production systems, globalization and technological progress lead to increasing requirements regarding part quality, delivery time and costs. Hence, today’s production is challenged much more than a few years ago: it has to be very flexible and produce economically small batch sizes to satisfy consumer’s demands and avoid unnecessary stock. Furthermore, a trend towards increasing functional integration continues to lead to an ongoing miniaturization of sheet metal components. In the industry of electric connectivity for example, the miniaturized connectors are manufactured by progressive tools, which are usually used for very large batches. These tools are installed in mechanical presses and then set up by a technician, who has to manually adjust a wide range of punch-bending operations. Disturbances like material thickness, temperatures, lubrication or tool wear complicate the setup procedure. In prospect of the increasing demand of production flexibility, this time-consuming process has to be handled more and more often. In this paper, a new approach for a model-based setup assistant is proposed as a solution, which is exemplarily applied in combination with a progressive tool. First, progressive tools, more specifically, their setup process is described and based on that, the challenges are pointed out. As a result, a systematic process to set up the machines is introduced. Following, the process is investigated with an FE-Analysis regarding the effects of the disturbances. In the next step, design of experiments is used to systematically develop a regression model of the system’s behaviour. This model is integrated within an optimization in order to calculate optimal machine parameters and the following necessary adjustment of the progressive tool due to the disturbances. Finally, the assistant is tested in a production environment and the results are discussed.

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