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See detailCu2SnS3-based thin film solar cell from electrodeposition-annealing route
Robert, Erika UL; De Wild, Jessica UL; Dale, Phillip UL

in IEEE Proceedings (2015, June)

Cu2SnS3 is a new emerging material for thin film photovoltaics, composed of three abundant and non toxic elements. Its p-type conductivity, bandgap of 0.93 eV and absorption coefficient above 104 cm-1 ... [more ▼]

Cu2SnS3 is a new emerging material for thin film photovoltaics, composed of three abundant and non toxic elements. Its p-type conductivity, bandgap of 0.93 eV and absorption coefficient above 104 cm-1 make it a promising absorber layer for p-n heterojunction devices. In this study, the Cu2SnS3 absorber is synthesized from electroplated stacked Cu-Sn precursors further annealed in chalcogen atmosphere (S and SnS). The electroplating has been processed on upscaled 45 x 50 mm2 Mo-coated soda-lime glass substrates on which the metallic layers seem to delaminate easily from the substrate due to increased stress between them. To reduce this stress the precursors are subjected to pre-alloying treatments. The effects of pre-alloying are investigated in terms of final absorber morphology, composition and crystal structure. Precursors are annealed at 250°C and 350°C. The prealloying at 350°C is far above the melting point of Sn around 230°C and these samples show de-wetting. The as-deposited and 250°C pre-alloyed samples are processed further into absorber layers and solar cells. The finished absorber layers show mainly monoclinic Cu2SnS3. Absorbers completed into devices show a device power conversion efficiency of 0.64%. The spectral response suggests the existence of two bandgaps, consistent with previous results. [less ▲]

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See detailCu2ZnSnSe4 device obtained by formate chemistry for metallic precursor layer fabrication
Tombolato, Sara; Berner, Ulrich Maximilian UL; Colombara, Diego UL et al

in Solar Energy (2015), 116

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See detailCu2ZnSnSe4 polymorphs and secondary phases: characterization by Raman spectroscopy and photoluminescence
Djemour, M'hamed Rabie UL

Doctoral thesis (2014)

Cu2ZnSn(S,Se)4 (CZTS/Se)has the necessary properties to be suitable as a thin film solar cell absorber. The reported record e ciencies for pure CZTSe are measured on CZTSe absorbers of di erent band gaps ... [more ▼]

Cu2ZnSn(S,Se)4 (CZTS/Se)has the necessary properties to be suitable as a thin film solar cell absorber. The reported record e ciencies for pure CZTSe are measured on CZTSe absorbers of di erent band gaps (0.96 eV and 1 eV as extracted from photoluminescence (PL), for example) although they were supposed to be the same material. This di fference in band gaps is usually explained by a diff erent order of the composing elements leading to crystal structures from other space groups (polymorphs) which have di erent band gaps. Various polymorphs and secondary phases are possible. This implies the importance of possessing tools to discernate the phases that tend to form whilst CZTSe is grown. This is one main goal of this thesis. The main measurement techniques employed during this thesis are Photoluminescence (PL) and Raman spectroscopy. Both are optical, contact-less and non-destructive characterization techniques. Following on from the first chapter which provides relevant background information about the di fferent polymorphs, secondary phases and measurement techniques used, the second chapter introduces the setup and the sample preparation techniques. The third chapter reports the fi rst results of this thesis: the discrimination of secondary phases encountered during the growth of CZTSe solar cell absorbers by Raman and PL. Chapter four discusses the Raman spectrum of CZTSe, especially focusing on the asymmetry of the mode of highest intensity, looking at the origins of this broadening. Additionally, a polarization and orientation Raman study is presented assigning the modes to their symmetry, therefore allowing the di erentiation between crystals from various polymorphs. The next chapter examines the luminescences attributed to CZTSe. An intensity dependent PL study assigns the various luminescences encountered to a mixture of band gaps. In the fi nal chapter, the findings reported on in this thesis are briefly summarized and discussed in the context of the ongoing research on the subject matter. [less ▲]

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See detailCu2ZnSnSe4 thin film solar cells produced by selenisation of magnetron sputtered precursors
Zoppi, Guillaume; Forbes, Ian; Miles, Robert W. et al

in Progress in Photovoltaics (2009), 17(5), 315-319

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See detailCu2ZnSnSe4 thin film solar cells produced via co-evaporation and annealing including a SnSe2 capping layer
Redinger, Alex UL; Mousel, Marina; Djemour, Rabie et al

in PROGRESS IN PHOTOVOLTAICS (2014), 22(1), 51-57

Cu2ZnSnSe4 (CZTSe) thin film solar cells have been produced via co-evaporation followed by a high-temperature annealing. In order to reduce the decomposition of the CZTSe, a SnSe2 capping layer has been ... [more ▼]

Cu2ZnSnSe4 (CZTSe) thin film solar cells have been produced via co-evaporation followed by a high-temperature annealing. In order to reduce the decomposition of the CZTSe, a SnSe2 capping layer has been evaporated onto the absorber prior to the high-temperature treatment. This eliminates the Sn losses due to SnSe evaporation. A solar cell efficiency of 5.1 could be achieved with this method. Moreover, the device does not suffer from high series resistance, and the dominant recombination pathway is situated in the absorber bulk. Finally different illumination conditions (white light, red light, and yellow light) reveal a strong loss in fill factor if no carriers are generated in the CdS buffer layer. This effect, known as red-kink effect, has also been observed in the closely related Cu(In,Ga)Se-2 thin film solar cells. Copyright (c) 2013 John Wiley Sons, Ltd. [less ▲]

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See detailCUBA: Artificial conviviality and user-behaviour analysis in web-feeds
Kaufmann, Sascha UL

Doctoral thesis (2010)

Conviviality is a concept of great depth that plays an important role in any social interaction. A convivial relation between individuals is one that allows the participating individuals to behave and ... [more ▼]

Conviviality is a concept of great depth that plays an important role in any social interaction. A convivial relation between individuals is one that allows the participating individuals to behave and interact with each other following a set of conventions that are shared, commonly agreed upon, or at least understood. This presupposes an implicit or an explicit regulation mechanism based on consensus or social contracts and applies to the behaviours and interactions of participating individuals. With respect to an intelligent web-based system, an applicable social contribution is the give of assistance to other users in situations that are unclear and in guiding him to find the right decision whenever a conflict arises. Such a convivial social biotope deeply depends on both implicit and explicit co-operation and collaboration of natural users inside a community. Here, the individual conviviality may benefit from “The Wisdom of Crowds”, which fosters a dynamic understanding of the user’s behaviour and a strong influence of an individual’s well being to another person(s). The web-based system CUBA focus on such a behavioural analysis through profiling and demonstrates a convivial stay within a web-based feed system. [less ▲]

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See detailA Cubesat-ready Phase Synchronization Digital Payload for Coherent Distributed Remote Sensing Missions
Querol, Jorge UL; Merlano Duncan, Juan Carlos UL; Martinez Marrero, Liz UL et al

in Proceedings of the 2021 International Geoscience and Remote Sensing Symposium (2021, July 15)

Distributed antenna arrays, fractionated payloads and cooperative platforms can provide unprecedented performance in the next generation of spaceborne communications and remote sensing systems. Remote ... [more ▼]

Distributed antenna arrays, fractionated payloads and cooperative platforms can provide unprecedented performance in the next generation of spaceborne communications and remote sensing systems. Remote phase synchronization of physically separated oscillators is the first step towards a coherent operation of distributed systems. This work shows the preliminary results of a TDD remote phase synchronization algorithm with a master-follower architecture. Herein, we describe the implementation and validation of the proposed algorithm. The implementation has been conducted in a Cubesat-ready software defined radio and validated at the end-to-end satellite communications testbed available at the University of Luxembourg. [less ▲]

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See detailCubic Sieve Congruence of the Discrete Logarithm Problem, and fractional part sequences
Venkatesh, Srinivas Vivek UL; C. E. Veni Madhavan

in Journal of Symbolic Computation (2014), 64

The Cubic Sieve Method for solving the Discrete Logarithm Problem in prime fields requires a nontrivial solution to the Cubic Sieve Congruence (CSC) $ x^3 \equiv y^2 z (mod p) $, where 'p' is a given ... [more ▼]

The Cubic Sieve Method for solving the Discrete Logarithm Problem in prime fields requires a nontrivial solution to the Cubic Sieve Congruence (CSC) $ x^3 \equiv y^2 z (mod p) $, where 'p' is a given prime number. A nontrivial solution must also satisfy $ x^3 \neq y^2 z $ and $ 1 <= x,y,z < p^a $, where 'a' is a given real number such that $ 1/3 < a <= 1/2 $. The CSC problem is to find an efficient algorithm to obtain a nontrivial solution to CSC. CSC can be parametrized as $ x \equiv v^2 z (mod p) $ and $ y \equiv v^3 z (mod p) $. In this paper, we give a deterministic polynomial-time ($ O(ln^3 p) $ bit-operations) algorithm to determine, for a given 'v', a nontrivial solution to CSC, if one exists. Previously it took $ õ(p^a) $ time in the worst case to determine this. We relate the CSC problem to the gap problem of fractional part sequences, where we need to determine the non-negative integers 'N' satisfying the fractional part inequality $ {\theta N} < \phi $ ($ \theta $ and $ \phi $ are given real numbers). The correspondence between the CSC problem and the gap problem is that determining the parameter 'z' in the former problem corresponds to determining 'N' in the latter problem. We also show in the $ a = 1/2 $ case of CSC that for a certain class of primes the CSC problem can be solved deterministically in $ õ(p^{1/3}) $ time compared to the previous best of $ õ(p^{1/2}) $. It is empirically observed that about one out of three primes is covered by the above class. [less ▲]

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See detailCue reactivity in male restrained eaters: the role of negative cognitions as predictors of food intake
Hilbert, Anja; Vögele, Claus UL; Himmelmann, Uta

in Eating and Weight Disorders (2007), 12

OBJECTIVE: While restrained eating is one of the most well-established risk factors of eating disorders in females, its role for eating disturbances in males remains largely unclear. The present study ... [more ▼]

OBJECTIVE: While restrained eating is one of the most well-established risk factors of eating disorders in females, its role for eating disturbances in males remains largely unclear. The present study investigates eating behaviour in response to food cues and negative cognitions in male restrained eaters. METHODS: Twenty-four restrained eaters and 21 unrestrained eaters volunteered in a cue reactivity experiment consisting of two exposure trials with and without response prevention. Food and macronutrient intake were monitored, and negative cognitions were assessed using a self-report cognition inventory. RESULTS: Male restrained eaters consumed a larger amount of food, specifically carbohydrates, than unrestrained eaters. This greater food intake was predicted by negative cognitions about self-esteem and occurred in restrained eaters who had reported binge eating episodes in the diagnostic interview. DISCUSSION: Results suggest marked cue reactivity in male restrained eaters with an increased risk of overeating in those who experience low situational self-esteem and who are binge eaters. [less ▲]

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See detailCue reactivity modulates proactive and reactive motor response inhibition in frequent gamblers.
Brevers, Damien UL; He, Qinghua; Keller, Brenton et al

in Frontiers in Aging Neuroscience (2016)

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See detailCuInSe2 Precursor Films Electro-Deposited Directly onto MoSe2
Cummings, Charles Y.; Zoppi, Guillaume; Forbes, Ian et al

in Journal of Electroanalytical Chemistry (2010), 645(1), 16-21

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See detailCuInSe2 semiconductor formation by laser annealing
Meadows, Helen UL; Regesch, David UL; Thevenin, Maxime UL et al

in Thin Solid Films (2014)

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See detailCuInSe2 thin film solar cells synthesised from electrodeposited binary selenide precursors
Fischer, Johannes UL

Doctoral thesis (2012)

The box must contain a summary in a maximum of 1,700 characters, spaces included. The fabrication of a CuInSe2 thin film solar cell from an electrodeposited precursor stack consisting of indium selenide ... [more ▼]

The box must contain a summary in a maximum of 1,700 characters, spaces included. The fabrication of a CuInSe2 thin film solar cell from an electrodeposited precursor stack consisting of indium selenide and copper selenide layers is demonstrated. A best conversion efficiency of 5.5% was achieved, a higher efficiency than previously reported in literature. The thesis focuses on three main parts: (i) electrochemistry of indium selenide: The incorporation of indium in the deposit requires the presence of selenium species. The obtained film consists of both amorphous In2Se3 and elemental Se. The Se/In ratio depends on the applied potential, although the deposition is mass transport controlled limited by the selenium ion concentration. The potential controls the balance of reduction kinetics between the In2Se3 and elemental Se and both compete for the same intermediate selenium species. (ii) phase reactions during annealing: The small interface area between the electrodeposited indium selenide and the copper selenide layer slows down the interdiffusion during the annealing process. Therefore the temperature required to react the precursor is higher than reported for similar stacks in literature. Copper selenide is retained at the surface for a longer time during the annealing process, where it undergoes the transitions CuSe2 => CuSe => Cu2Se. (iii) loss mechanisms in the solar cell: The highest solar cell conversion efficiency was obtained from a stoichiometric precursor compromising the advantages and disadvantages of Cu-poor and Cu-rich growth. The Cu-poor grown absorber showed a reverse pn-junction at the backside due to an incomplete reaction of the stack. The efficiency of the Cu-rich grown solar cell was limited by high interface recombination. [less ▲]

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See detailLa cuisine bonifacienne. Un marqueur emblématique face au changement
Reckinger, Rachel UL

in Strade. Travaux du Centre d’Etudes Corses n° 7 (1999)

Detailed reference viewed: 46 (0 UL)
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See detailCultivating Children and Youth: Transnational Explorations of the Urban and the Natural
Allender, Tim; Dussel, Inés; Grosvenor, Ian et al

Scientific Conference (2018)

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See detailCultivating humanity or educating the human? Two options for education in the knowledge age
Biesta, Gert UL

in Asia Pacific Education Review (2014), 15(1), 13-19

Detailed reference viewed: 462 (5 UL)
See detailCultivation and characterization of human midbrain organoids in sensor integrated microfluidic chips
Spitz, Sarah; Zanetti, Cristian; Bolognin, Silvia UL et al

E-print/Working paper (2019)

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See detailCultiver l'“être-ensemble”, même dans son salon : une approche communicationnelle des dvd de metal
Schall, Céline UL

in Monbelet, Alexis; Ferrand, Laure (Eds.) Le rock et le metal : regards et perspectives des sciences sociales (2012)

Résumé : Cette intervention propose d’étudier le DVD de musique metal en tant que dispositif de médiation. L’approche communicationnelle permet d’analyser les modalités d’instauration du sentiment ... [more ▼]

Résumé : Cette intervention propose d’étudier le DVD de musique metal en tant que dispositif de médiation. L’approche communicationnelle permet d’analyser les modalités d’instauration du sentiment d’« être ensemble », si cher aux fans de metal et ce même lorsqu’on regarde un DVD seul, dans son salon. Cette médiation passe essentiellement par trois modalités, qui se construisent aux niveaux de l’énonciation, de la textualité et des représentations véhiculées par le film. Ainsi, quand Metallica, Iron Maiden ou Mötorhead fondent la relation au spectateur sur l’intimité dévoilée de ses membres (avec des procédés filmiques proches de la téléréalité), Slipknot ou Down préfèrent placer le spectateur en immersion dans l’ambiance (et l’inconfort) du concert, tout en jouant sur les codes et les représentations les plus « rebelles » du metal... [less ▲]

Detailed reference viewed: 46 (2 UL)