1,721,006 research outputs found
Upscaling of Indium Tin Oxide (ITO)-Free Polymer Solar Cells:Performance, Scalability, Stability, and Flexibility
Get PDFPlastsolceller (PSC) har til formål at producere ren energi, der er prismæssigt konkurrencedygtig sammenlignet med energi produceret af konventionelle fossile brændsler. Fra et miljømæssigt perspektiv sammenlignes PSC allerede positivt til andre solcelle-teknologier i form af færre emissioner af drivhusgasser under produktionen. Konkurrenceevnen for prisen på PSC opnås ved brug af billige materialer og høj hastigheds rulle-til-rulle (R2R) trykning samt coating teknikker. De bedste PSC produceret i laboratorieforhold er langt fra visionen om den meget udbredte billige solcelle, da disse mest er fokuseret på at øget effektiviteten gennem design med lille vægt på valget af materialer, driftsstabilitet og omfattende behandling. Indium-tin-oxid (ITO), den mest almindeligt anvendte transparente leder, repræsenterer størstedelen af omkostningerne og energi fodaftrykket i form af materialer og forarbejdning i et konventionelt PSC modul. Desuden vil manglen på indium skabe en flaskehals i PSC industrien og samtidig er ITOs struktur en hindring for hurtig behandling af PSC på fleksible substrater, samt for fleksibiliteten af slutproduktet. Udskiftning af ITO med billige alternativer er således afgørende for den kommercielle succes for PSC.Med disse bekymringer i mente, har mit ph.d.-studie bidraget til udvikling og evaluering af alternativer til ITO i laboratorieceller, opskalering af ITO-fri koncepter fra laboratorium til R2R produceret –moduler med stort areal og integration af disse moduler i forbruger-applikationer til demonstration. Derfor er denne afhandling organiseret i ni kapitler. Kapitel 1 placerer PCS på et energiforsynings-verdenskort. Det ledende spørgsmål i kapitel 2 er hvorfor skal PSC videreføres? Her gives en kortfattet, men omfattende introduktion til PSC, samt problemet med ITO og mulige løsninger. Det indeholder også konkrete mål, der blev sat før begyndelsen af ph.d.-studiet, som giver en ramme for de senere kapitler. En helhedsvurdering af flere ITO-fri koncepter blev udført for at bestemme deres opskalerings kompatibilitet (kapitel 3). Resultaterne fremhævede tre arkitekturer, der repræsenterede forskellige fordele med hensyn til solcellernes ydeevne, stabilitet og lave forarbejdningsomkostninger. Disse tre arkitekturer blev opskaleret (kapitel 5-7) ved hjælp R2R teknikker beskrevet i detaljer i kapitel 4. En af de tre opskalerede arkitekturer (kapitel 7) udgjorde et effektivt alternativ til ITO i form af solcelle præstation og blev yderligere undersøgt for stabilitet og fleksibilitet. Disse moduler blev yderligere integreret i en kreditkortformat-laserpointer til demonstration. Nieves Espinosa, en kollega, har gennemført livscyklusanalyser (LCA) på alle tre opskalerede ITO-fri arkitekturer. Data fra hendes offentliggjorte arbejde (kapitel 8) er kortfattet beskrevet og sammenligner LCA for de ITO-fri arkitekturer med henblik på at afgøre hvilken teknologi kan videreføres. LCA resultaterne for ITO-fri arkitekturer er også sammenlignes med opskalerede ITO-baserede PSC samt mod andre fotovoltaiske teknologier. Endelig sætter sidste kapitel (kapitel 9) afhandlingen i perspektiv og identificerer fremtidige udfordringer.Polymer solar cells (PSCs) aim to produce clean energy that is cost-competitive to energy produced by fossil fuel-based conventional energy sources. From an environmental perspective, PSCs already compares favorably to other solar cell technologies in terms of fewer emissions of greenhouse gases during production. The costcompetitiveness of PSCs is envisioned achievable by the use of inexpensive materials and high throughput roll-to-roll (R2R) printing and coating techniques. The state-ofthe-art of the laboratory PSCs is, however, far removed from the vision of the widely disseminated low-cost solar cells as the laboratory solar cells are mostly focused on increasing the power conversion efficiency through materials design with little emphasis on the choice of materials, operational stability and large-scale processing. Indium-tinoxide (ITO), the commonly used transparent conductor, represents majority of the share of cost and energy footprint in terms of materials and processing in a conventional PSC module. Furthermore, the scarcity of indium is feared to create bottleneck in the dawning PSC industry and its brittle nature is an obstacle for fast processing of PSCs on flexible substrates as well as for applications in flexible end products. Thus, the replacement of ITO with low-cost alternatives is crucial for the commercial feasibility of PSCs.Encompassing these concerns, my PhD study has contributed to the development and evaluation of alternatives to ITO in laboratory cells, upscaling of ITO-free concepts from laboratory cells to R2R produced large-area modules, and integration of these module in demonstrator consumer applications. Accordingly, this dissertation is organized into nine chapters. Chapter 1 is aimed at contextualizing PSCs on the world energy map. It aims to address the question: why should PSCs be pursued? Chapter 2 attempts to provide a concise yet encompassing introduction to PSCs; and the problem with ITO and possible solutions. It also lays out specific targets that were set before the beginning of PhD study which provides a frame-of-reference for the later chapters. A holistic evaluation of several ITO-free concepts was carried out to determine low-cost upscaling compatibility of these concepts (Chapter 3). The results highlighted three architectures that represented different competencies with regards to photovoltaic performance, stability, and low-cost processing. These three architectures were upscaled (Chapter 5-7) using R2R techniques described in detail in Chapter 4. One of the three upscaled architecture (Chapter 7) represented an efficient alternative to ITO in terms of photovoltaic performance and were further investigated for stability and flexibility. These modules were then integrated in a credit-card size laser pointer for demonstration purposes. A colleague, Nieves Espinosa, has conducted life-cycle analyses (LCA) on all the three upscaled ITO-free architectures. Drawing upon the data from her published work, Chapter 8 provides concise and comparative LCA of the three upscaled ITO-free architectures in order to determine which technology can be pursued further among the three architectures. LCA results of the ITO-free architectures are also compared against ITO-based upscaled PSCs as well as against other photovoltaic technologies. Finally, the last chapter (Chapter 9) puts everything in the nutshell and identifies future challenges
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
All solution processing of ITO-free organic solar cell modules directly on barrier foil
No full textIn this study, we demonstrate fully solution processed semi-transparent silver electrodes on flexible substrates having a sheet resistance as low as 5Ω/□ and transmittance of ∼30% at 550nm. We demonstrate the use of this electrode as a substitute for ITO in an inverted organic solar cell (OSC) with the layer sequence, PET/Ag/ZnO/P3HT:PCBM/PEDOT:PSS/Ag where illumination is achieved through the first Ag layer. Power conversion efficiency of up to 1.6% under 1 sun illumination (100mWcm−2 and AM1.5G) is achieved for small area (1cm2) test devices. We further demonstrate scalability of the semi-transparent Ag electrode fabrication in a roll-to-roll (R2R) process using slot-die coating. This electrode is further utilized in R2R processing of large area modules (active area 35.5cm2) where all layers in the modules are R2R processed with solution-based materials in ambient conditions without any use of vacuum steps. We further demonstrate the possibility of using barrier foil as the substrate in the R2R processing of modules. Module performance is evaluated by current–voltage characterization and Light Beam Induced Current (LBIC imaging). Such a semi-transparent Ag electrode incurs very little material and processing cost and is a cost-effective alternative to ITO for low-cost organic solar cells
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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