排序方式: 共有19条查询结果,搜索用时 31 毫秒
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Wolfram Witte Daniel Abou‐Ras Karsten Albe Gottfried H. Bauer Frank Bertram Christian Boit Rudolf Brüggemann Jürgen Christen Jens Dietrich Axel Eicke Dimitrios Hariskos Matthias Maiberg Roland Mainz Max Meessen Mathias Müller Oliver Neumann Thomas Orgis Stefan Paetel Johan Pohl Humberto Rodriguez‐Alvarez Roland Scheer Hans‐Werner Schock Thomas Unold Alfons Weber Michael Powalla 《Progress in Photovoltaics: Research and Applications》2015,23(6):717-733
The gallium gradient in Cu(In,Ga)Se2 (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co‐evaporation processes, plays a key role in the device performance of CIGS thin‐film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X‐ray measurements. In addition, the gallium grading of a CIGS layer grown with an in‐line co‐evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth‐dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co‐evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi‐Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross‐sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper‐vacancy‐mediated indium and gallium diffusion in CuInSe2 and CuGaSe2 were calculated using density functional theory. The migration barrier for the InCu antisite in CuGaSe2 is significantly lower compared with the GaCu antisite in CuInSe2, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co‐evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Roland Mainz Alfons Weber Humberto Rodriguez‐Alvarez Sergiu Levcenko Manuela Klaus Paul Pistor Reiner Klenk Hans‐Werner Schock 《Progress in Photovoltaics: Research and Applications》2015,23(9):1131-1143
Ga segregation at the backside of Cu(In,Ga)Se2 solar cell absorbers is a commonly observed phenomenon for a large variety of sequential fabrication processes. Here, we investigate the correlation between Se incorporation, phase formation and Ga segregation during fast selenisation of Cu–In–Ga precursor films in elemental selenium vapour. Se incorporation and phase formation are analysed by real‐time synchrotron‐based X‐ray diffraction and fluorescence analysis. Correlations between phase formation and depth distributions are gained by interrupting the process at several points and by subsequent ex situ cross‐sectional electron microscopy and Raman spectroscopy. The presented results reveal that the main share of Se incorporation takes place within a few seconds during formation of In–Se at the top part of the film, accompanied by outdiffusion of In out of a ternary Cu–In–Ga phase. Surprisingly, CuInSe2 starts to form at the surface on top of the In–Se layer, leading to an intermediate double graded Cu depth distribution. The remaining Ga‐rich metal phase at the back is finally selenised by indiffusion of Se. On the basis of a proposed growth model, we discuss possible strategies and limitations for the avoidance of Ga segregation during fast selenisation of metallic precursors. Solar cells made from samples selenised with a total annealing time of 6.5 min reached conversion efficiencies of up to 14.2 % (total area, without anti‐reflective coating). The evolution of the Cu(In,Ga)Se2 diffraction signals reveals that the minimum process time for high‐quality Cu(In,Ga)Se2 absorbers is limited by cation ordering rather than Se incorporation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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I. Riedel J. RiedigerJ. Ohland J. KellerM. Knipper J. ParisiR. Mainz S. Merdes 《Solar Energy Materials & Solar Cells》2011,95(1):270-273
CuInS2-based solar cells have a strong potential of achieving high efficiencies due to their ideal band gap of 1.5 eV. A further increase in the efficiency is expected from doping the absorber film with gallium due to enlargement of the band gap (Eg) and correspondingly the open-circuit voltage (VOC). We investigated Cu(In,Ga)S2 solar cells obtained from stacked metal layers sputtered from In and (Cu,Ga) targets followed by rapid thermal processing (RTP) in sulfur vapor. Depending on the actual RTP temperature profile, the films might exhibit CuInS2/CuGaS2 (top/bottom) segregation, which is rather detrimental for a large VOC. We found that only precursors sulfurized at sufficiently high temperatures exhibit the desired interdiffusion of the segregated CuInS2/CuGaS2 layers resulting in an increased VOC. Moreover, temperature dependent current-voltage profiling (suns-VOC-analysis) yielded strong indications for improved current collection and reduced losses for devices with proper interdiffusion of the CuInS2/CuGaS2 layers. A more fundamental question is related to the variation and formation of defect states in differently processed absorber films. The studied samples were thus further investigated by means of admittance spectroscopy, which allowed us to confirm the presence of three individual defect states in both absorber configurations. Two defects exhibit activation energies, which remain unchanged upon varying the RTP temperature whereas a third state exhibits significantly increased activation energy in devices showing interdiffusion of CuInS2/CuGaS2 layers. According to the characteristic shift of the conduction band edge upon Ga-doping we conclude that the latter defect level corresponds with the minority carriers in the p-type absorbers. 相似文献
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Klara Suchan Justus Just Pascal Beblo Carolin Rehermann Aboma Merdasa Roland Mainz Ivan G. Scheblykin Eva Unger 《Advanced functional materials》2023,33(3):2206047
Photo- and charge-carrier-induced ion migration is a major challenge when utilizing metal halide perovskite semiconductors for optoelectronic applications. For mixed iodide/bromide perovskites, the compositional instability due to light- or electrical bias induced phase-segregation restricts the exploitation of the entire bandgap range. Previous experimental and theoretical work suggests that excited states or charge carriers trigger the process, but the exact mechanism is still under debate. To identify the mechanism and cause of light-induced phase-segregation phenomena, the full compositional range of methylammonium lead bromide/iodide samples are investigated, MAPb(BrxI1-x)3 with x = 0…1, by simultaneous in situ X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy during illumination. The quantitative comparison of composition-dependent in situ XRD and PL shows that at excitation densities of 1 sun, only the initial stage of photo-segregation is rationalized with the previously established thermodynamic models. However, a progression of the phase segregation is observed that is rationalized by considering long-lived accumulative photo-induced material alterations. It is suggested that (additional) photo-induced defects, possibly halide vacancies and interstitials, need to be considered to fully rationalize light-induced phase segregation and anticipate the findings to provide crucial insight for the development of more sophisticated models. 相似文献
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To make health care more responsive to patient needs, insight into patient priorities is needed. A systematic literature review, using electronic and manual searches, was made of studies on patient priorities with regard to primary health care. Data-extraction was performed by two researchers, followed by systematic analyses of study features. 57 studies were included. The aspects of care and methods used showed a wide variation. Aspects most often included were "informativeness", "humaneness" and "competence/accuracy". Based on an analysis of 19 studies, the following aspects were seen by patients as most important in more than 50% of the studies that included them: "humaneness", "competence/accuracy", "patients' involvement in decisions", "time for care", "other aspects of availability/accessibility", "informativeness", "exploring patients' needs", "other aspects of relation and communication" and "availability of special services". 相似文献
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J. Großfeld H. Mohler H. -A. Oelkers W. Schreiber R. Grau Bäurle Steinbeck Brüning K. Rintelen Seige Kanitz Symanski Pawletta Willy Lindner E. Dinslage Beckel Schwaibola Griebel O. Windhausen Schloemer Hofmann K. Höll W. Wodsak F. Dörbeck Jesser Heyns Haevecker Felicitas Rolleri K. Müller Zacher Patzsch und Mainz 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1941,82(2):157-208
Ohne Zusammenfassung 相似文献
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Sabine Meyer Andi Mainz Jan‐Christoph Kehr Prof. Roderich D. Süssmuth Prof. Elke Dittmann 《Chembiochem : a European journal of chemical biology》2017,18(24):2376-2379
The biosynthesis of the potent cyanobacterial hepatotoxin microcystin involves isopeptide bond formation through the carboxylic acid side chains of d ‐glutamate and β‐methyl d ‐aspartate. Analysis of the in vitro activation profiles of the two corresponding adenylation domains, McyE‐A and McyB‐A2, either in a didomain or a tridomain context with the cognate thiolation domain and the upstream condensation domain revealed that substrate activation of both domains strictly depended on the presence of the condensation domains. We further identified two key amino acids in the binding pockets of both adenylation domains that could serve as a bioinformatic signature of isopeptide bond‐forming modules incorporating d ‐glutamate or d ‐aspartate. Our findings further contribute to the understanding of the multifaceted role of condensation domains in nonribosomal peptide synthetase assembly lines. 相似文献
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John Thornley Richard P. Muller Daniel T. Mainz Tahir ?ain William A. Goddard III 《Journal of Computer-Aided Materials Design》2001,8(2-3):173-184
The recent advent of inexpensive commodity multiprocessor computers with standardized operating system support for lightweight
threads provides computational chemists and other scientists with an exciting opportunity to develop sophisticated new approaches
to materials simulation. We contrast the flexible performance characteristics of lightweight threading with the restrictions
of traditional scientific supercomputing, based on our experiences with multithreaded molecular dynamics simulation. Motivated
by the results of our molecular dynamics experiments, we propose an approach to multi-scale materials simulation using highly
dynamic thread creation and synchronization within and between concurrent simulations at many different scales. This approach
will enable extremely realistic simulations, with computing resources dynamically directed to areas where they are needed.
Multi-scale simulations of this kind require large amounts of processing power, but are too sophisticated to be expressed
using traditional supercomputing programming models. As a result, we have developed a high-level programming system called
Sthreads that allows highly dynamic, nested multithreaded algorithms to be expressed. Program development is simplified through
the use of innovative synchronization operations that allow multithreaded programs to be tested and debugged using standard
sequential methods and tools. For this reason, Sthreads is very well suited to the complex multi-scale simulation applications
that we are developing.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献