TY - JOUR A1 - Hempel, Hannes A1 - Savenjie, Tom J. A1 - Stolterfoht, Martin A1 - Neu, Jens A1 - Failla, Michele A1 - Paingad, Vaisakh C. A1 - Kužel, Petr A1 - Heilweil, Edwin J. A1 - Spies, Jacob A. A1 - Schleuning, Markus A1 - Zhao, Jiashang A1 - Friedrich, Dennis A1 - Schwarzburg, Klaus A1 - Siebbeles, Laurens D. A. A1 - Dörflinger, Patrick A1 - Dyakonov, Vladimir A1 - Katoh, Ryuzi A1 - Hong, Min Ji A1 - Labram, John G. A1 - Monti, Maurizio A1 - Butler-Caddle, Edward A1 - Lloyd-Hughes, James A1 - Taheri, Mohammad M. A1 - Baxter, Jason B. A1 - Magnanelli, Timothy J. A1 - Luo, Simon A1 - Cardon, Joseph M. A1 - Ardo, Shane A1 - Unold, Thomas T1 - Predicting solar cell performance from terahertz and microwave spectroscopy JF - Advanced energy materials N2 - Mobilities and lifetimes of photogenerated charge carriers are core properties of photovoltaic materials and can both be characterized by contactless terahertz or microwave measurements. Here, the expertise from fifteen laboratories is combined to quantitatively model the current-voltage characteristics of a solar cell from such measurements. To this end, the impact of measurement conditions, alternate interpretations, and experimental inter-laboratory variations are discussed using a (Cs,FA,MA)Pb(I,Br)(3) halide perovskite thin-film as a case study. At 1 sun equivalent excitation, neither transport nor recombination is significantly affected by exciton formation or trapping. Terahertz, microwave, and photoluminescence transients for the neat material yield consistent effective lifetimes implying a resistance-free JV-curve with a potential power conversion efficiency of 24.6 %. For grainsizes above approximate to 20 nm, intra-grain charge transport is characterized by terahertz sum mobilities of approximate to 32 cm(2) V-1 s(-1). Drift-diffusion simulations indicate that these intra-grain mobilities can slightly reduce the fill factor of perovskite solar cells to 0.82, in accordance with the best-realized devices in the literature. Beyond perovskites, this work can guide a highly predictive characterization of any emerging semiconductor for photovoltaic or photoelectrochemical energy conversion. A best practice for the interpretation of terahertz and microwave measurements on photovoltaic materials is presented. KW - lifetime KW - microwaves KW - mobility KW - solar cells KW - terahertz Y1 - 2022 U6 - https://doi.org/10.1002/aenm.202102776 SN - 1614-6832 SN - 1614-6840 VL - 12 IS - 13 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Rabin, Shari T1 - Mobile Jews and Porous Borders BT - A Transnational History in the Nineteenth Century JF - PaRDeS : Journal of the Association for Jewish Studies in Germany JF - PaRDeS : Zeitschrift der Vereinigung für Jüdische Studien N2 - This article explores the multi-directional geographic trajectories and ties of Jews who came to the United States in the 19th century, working to complicate simplistic understandings of “German” Jewish immigration. It focuses on the case study of Henry Cohn, an ordinary Russian-born Jew whose journeys took him to Prussia, New York, Savannah, and California. Once in the United States he returned to Europe twice, the second time permanently, although a grandson ended up in California, where he worked to ensure the preservation of Cohn’s records. This story highlights how Jews navigated and transgressed national boundaries in the 19th century and the limitations of the historical narratives that have been constructed from their experiences. KW - modern Jewish history KW - transatlantic history KW - mobility KW - nineteenth century KW - United States KW - Russia KW - Prussia KW - moderne jüdische Geschichte KW - transatlantische Geschichte KW - Mobilität KW - 19. Jahrhundert KW - USA KW - Russland KW - Preußen Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-532822 SN - 978-3-86956-520-0 SN - 1614-6492 SN - 1862-7684 IS - 27 SP - 25 EP - 38 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Jiang, Wei A1 - Tao, Chen A1 - Stolterfoht, Martin A1 - Jin, Hui A1 - Stephen, Meera A1 - Lin, Qianqian A1 - Nagiri, Ravi C. R. A1 - Burn, Paul L. A1 - Gentle, Ian R. T1 - Hole-transporting materials for low donor content organic solar cells BT - charge transport and device performance JF - Organic electronics : physics, materials and applications N2 - Low donor content solar cells are an intriguing class of photovoltaic device about which there is still considerable discussion with respect to their mode of operation. We have synthesized a series of triphenylamine-based materials for use in low donor content devices with the electron accepting [6,6]-phenyl-C71-butyric acid methyl ester (PC(7)0BM). The triphenylamine-based materials absorb light in the near UV enabling the PC(7)0BM to be be the main light absorbing organic semiconducting material in the solar cell. It was found that the devices did not operate as classical Schottky junctions but rather photocurrent was generated by hole transfer from the photo-excited PC(7)0BM to the triphenylamine-based donors. We found that replacing the methoxy surface groups with methyl groups on the donor material led to a decrease in hole mobility for the neat films, which was due to the methyl substituted materials having the propensity to aggregate. The thermodynamic drive to aggregate was advantageous for the performance of the low donor content (6 wt%) films. It was found that the 6 wt% donor devices generally gave higher performance than devices containing 50 wt% of the donor. KW - photoexcited hole transfer KW - photocurrent generation KW - synthesis KW - hole KW - mobility KW - low donor content KW - Schottky junction Y1 - 2020 U6 - https://doi.org/10.1016/j.orgel.2019.105480 SN - 1566-1199 SN - 1878-5530 VL - 76 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pohlenz, Philipp A1 - Niedermeier, Frank T1 - The Bologna Process and the harmonisation of higher education systems in other world regions BT - a case from Southeast Asia JF - Innovation : the European journal of social sciences N2 - The Bologna Process has inspired harmonisation strategies for higher education systems in other parts of the world. However, developments in other contexts are not much under review in the European debate. The present article describes the case of Southeast Asia and the attempt to promote harmonisation of its higher education systems. It further compares the processes in ASEAN and the European Higher Education Area to then discuss open questions for future comparative research. To do so the authors re-contextualise data from a study in ASEAN against the background of future research needs in the field of higher education harmonisation. KW - ASEAN KW - Bologna Process KW - European Higher Education Area KW - higher education KW - quality assurance KW - harmonisation KW - regionalisation KW - diffusion KW - mobility Y1 - 2019 U6 - https://doi.org/10.1080/13511610.2019.1637248 SN - 1351-1610 SN - 1469-8412 VL - 32 IS - 4 SP - 481 EP - 494 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Love, John A. A1 - Feuerstein, Markus A1 - Wolff, Christian Michael A1 - Facchetti, Antonio A1 - Neher, Dieter T1 - Lead Halide Perovskites as Charge Generation Layers for Electron Mobility Measurement in Organic Semiconductors JF - ACS applied materials & interfaces N2 - Hybrid lead halide perovskites are introduced as charge generation layers (CGLs) for the accurate determination of electron mobilities in thin organic semiconductors. Such hybrid perovskites have become a widely studied photovoltaic material in their own right, for their high efficiencies, ease of processing from solution, strong absorption, and efficient photogeneration of charge. Time-of-flight (ToF) measurements on bilayer samples consisting of the perovskite CGL and an organic semiconductor layer of different thickness are shown to be determined by the carrier motion through the organic material, consistent with the much higher charge carrier mobility in the perovskite. Together with the efficient photon-to-electron conversion in the perovskite, this high mobility imbalance enables electron-only mobility measurement on relatively thin application-relevant organic films, which would not be possible with traditional ToF measurements. This architecture enables electron-selective mobility measurements in single components as well as bulk-heterojunction films as demonstrated in the prototypical polymer/fullerene blends. To further demonstrate the potential of this approach, electron mobilities were measured as a function of electric field and temperature in an only 127 nm thick layer of a prototypical electron-transporting perylene diimide-based polymer, and found to be consistent with an exponential trap distribution of ca. 60 meV. Our study furthermore highlights the importance of high mobility charge transporting layers when designing perovskite solar cells. KW - mobility KW - bulk heterojunction KW - time of flight KW - lead halide perovskites KW - charge generation layers Y1 - 2017 U6 - https://doi.org/10.1021/acsami.7b10361 SN - 1944-8244 VL - 9 SP - 42011 EP - 42019 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Borck, Rainald A1 - Übelmesser, Silke A1 - Wimbersky, Martin T1 - The Political Economics of Higher-Education Finance for Mobile Individuals JF - FinanzArchiv N2 - We study voting over higher-education finance in an economy with two regions and two separated labor markets. Households differ in their financial endowment and their children's ability. Nonstudents are immobile. Students decide where to study; they return home after graduation with exogenous probability. The voters of the two regions decide on whether to subsidize higher-education costs or to rely on tuition fees only. We find that in equilibrium, in both regions a majority votes for subsidies when the return probability is sufficiently small. When that probability is large, both regions opt for full tuition finance. KW - voting KW - higher education KW - financing scheme KW - mobility Y1 - 2015 U6 - https://doi.org/10.1628/001522115X14206439673215 SN - 0015-2218 SN - 1614-0974 VL - 71 IS - 1 SP - 82 EP - 105 PB - Mohr Siebeck CY - Tübingen ER - TY - JOUR A1 - Turner, Sarah T. A1 - Pingel, Patrick A1 - Steyrleuthner, Robert A1 - Crossland, Edward J. W. A1 - Ludwigs, Sabine A1 - Neher, Dieter T1 - Quantitative analysis of bulk heterojunction films using linear absorption spectroscopy and solar cell performance JF - Advanced functional materials N2 - A fundamental understanding of the relationship between the bulk morphology and device performance is required for the further development of bulk heterojunction organic solar cells. Here, non-optimized (chloroform cast) and nearly optimized (solvent-annealed o-dichlorobenzene cast) P3HT:PCBM blend films treated over a range of annealing temperatures are studied via optical and photovoltaic device measurements. Parameters related to the P3HT aggregate morphology in the blend are obtained through a recently established analytical model developed by F. C. Spano for the absorption of weakly interacting H-aggregates. Thermally induced changes are related to the glass transition range of the blend. In the chloroform prepared devices, the improvement in device efficiency upon annealing within the glass transition range can be attributed to the growth of P3HT aggregates, an overall increase in the percentage of chain crystallinity, and a concurrent increase in the hole mobilities. Films treated above the glass transition range show an increase in efficiency and fill factor not only associated with the change in chain crystallinity, but also with a decrease in the energetic disorder. On the other hand, the properties of the P3HT phase in the solvent-annealed o-dichlorobenzene cast blends are almost indistinguishable from those of the corresponding pristine P3HT layer and are only weakly affected by thermal annealing. Apparently, slow drying of the blend allows the P3HT chains to crystallize into large domains with low degrees of intra- and interchain disorder. This morphology appears to be most favorable for the efficient generation and extraction of charges. KW - Organic electronics KW - morphology KW - solar cells KW - mobility KW - absorption spectroscopy Y1 - 2011 U6 - https://doi.org/10.1002/adfm.201101583 SN - 1616-301X VL - 21 IS - 24 SP - 4640 EP - 4652 PB - Wiley-VCH CY - Weinheim ER -