1,720,955 research outputs found
Cu₂ZnSnS₄ nanoparticulate thin films and their solar cell characteristics
No full textThin film technology for solar cells has emerged as the most promising alternative since it can beat the absorption limit of crystalline silicon solar cells and has also an ideal band gap as compared to silicon. However, current thin films are based on rare and toxic elements such as cadmium and indium. Therefore, during the past 5-7 years, there has been a sudden increase in the interest to develop Cu₂ZnSnS₄ (CZTS) thin films (based on all non-toxic abundant elements) to facilitate the increasing demand for the electricity and its production. CZTS demonstrate a high optical absorption coefficient (10⁴ cmˉ¹), a suitable band gap (1.4-1.6 eV) and a high electrical conductivity, making it an ideal material for solar energy conversion applications. The aim of this study is to fabricate and characterize CZTS thin films and evaluate their solar cell performance. In this work, CZTS thin films were grown using two different processes such as electrodeposition and chemical synthesis approach. The first objective is to fabricate high quality quaternary CZTS thin films by single step electro deposition method followed by sulfurization at 550°C. For this, we systematically studied the role of deposition potential over compositional, structural and optical properties of the CZTS films. We discuss the nucleation and growth mechanism of the CZTS thin film and propose an optimum deposition potential of -1.4 V vs. Ag/AgCl to achieve an ideal composition, uniform growth (void free) with tunable optical properties. Using the chrono-amperometric data and the Scharifker and Hill model we found that the nucleation mechanism for CZTS thin film is instantaneous. Optical properties demonstrated the optimum band gap of 1.5 eV for kesterite CZTS films prepared from a precursor electrodeposited at -1.4 V vs. Ag/AgCl. CZTS thin films deposited at optimum potential and assembled into the solar cell structure demonstrated an efficiency of 5.0%. The work also includes the synthesis of size controlled kesterite phase CZTS nanoparticles. The nanoparticle size has been controlled from 2-8 (± 0.5) nm by a simple control of amine-to-precursor molar ratio. We demonstrate the synthesis of as much as 20 gm of quaternary chalcogenide nanoparticles powder in a single reaction, without a size-sorting process. The fabricated devices exhibit efficiencies ranging from 3.6% to 4.5% depending on the CZTS particles average diameter. Comparison of EQE data suggests that our current is mainly restricted by the collection losses. Further, we have incorporated the extrinsic impurities such as Fe and Mn (to replace Zn) or Se (to replace S) into CZTS in order to control secondary phase formation, micro structural and band gap variation of CZTS. It is demonstrated that the crystal structure, band gap, and photo response of CZTS thin films are affected by substitution of anion/cations. The absorption characteristics show the earth abundant compound Cu₂MSnS₄/Se₄ (M=Zn, Mn and Fe) band gaps are in the range of 1.0 to 1.5 eV with high optical absorption coefficients (~10⁴ cmˉ¹) in the visible region. The efficiency of CZTS solar cell is enhanced significantly from 4.5% to 7.6% with selenium doping. The variation of device performance may be ascribed to the changes in the micro-structure and band gap. A further improvement in the power conversion efficiency was achieved by embedding the silica nanoparticles (150 nm) into the CZTS absorber layer; we studied the effect of silica particles depth in the CZTS absorber layer on optical absorption and solar cell performance theoretically and experimentally as well. We fabricated the CZTS solar cells with 150 nm sized silica nanoparticles at the top, middle and bottom of the absorber layer for light-trapping. The best optical absorption and electrical efficiency (η=5.3%) is observed for particles placed at the middle-level of the absorber layer; this is 18% more than that of the reference cell (η=4.5%). Particles placed on the top lead to higher optical absorption but lower conversion efficiency compared to particles at the bottom.Thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy of the Indian Institute of Technology Bombay, India and Monash University, Australia
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
- …
