1,721,002 research outputs found
Application of Electrospray Deposition for Efficient and Stable Organic Photovoltaic Devices”
No full textOrganic solar cells can be processed from solution at room temperature and have been considered as an alternative photovoltaic technology, thus having been receiving considerable interest in the field of optoelectronics. Most importantly, their light weight, low cost, easy fabrication over large area and flexible devices are appealing to future\ud
organic electronics market for both economic and environmental reasons, as printing and coating technologies can be incorporated during the material process. In this\ud
work, we have investigated the application of electrospray deposition technique towards achieving high efficiency and stable organic solar cells. The main advantages of\ud
electrospray deposition (ESD) over other common deposition processes are: suitability for less soluble materials, lack of solvent evaporation effects, possibility for realizing\ud
multilayered devices and efficient usage of the materials. Among them, multilayered thin film growth is most important advantage of ESD which is difficult to achieve while\ud
using conventional solution process techniques like spin coating, dip-coating, screen printing, ink jet printing or spray coating etc, as dissolution of the bottom organic\ud
layer during the growth of top layer can not be avoided. In this systematic study, a number of issues concerning ESD have been tackled, from the optimization of the deposition parameters to eventually realizing efficient and stable organic photovoltaic devices. The first part of thesis comprised the electrical characterization of the ESD\ud
deposited sandwich structure Schottky diode using poly(3-hexylthiophene)(P3HT) in order to optimize various electrospray parameters. The results provide a description\ud
of various charge carrier transport parameters along with the determination of field dependent hole mobility and electric field activation parameter from the fitting of the\ud
experimental I-V curves. The hole mobility was determined as 2.7x10−7cm2/Vs and the value of electric field parameter is 3.45x10−4/m0:5/V0:5 which are comparable to the literature values. A clear evidence of the deep localized states within the band gap was observed via forward and backward I-V measurements. Following this promising\ud
outcome, we first fabricated and characterized hybrid photovoltaic devices from dispersed nanoparticles (TiO2) and polymer blend solution, results of which will be\ud
presented in the next chapter. From the Grazing incidence X-ray diffraction (GIXRD) measurements, it was found that increasing thermal annealing improves the self organization\ud
of P3HT chain in the film. However, after optimization processes such as tuning the ratio, solvent soaking and temperature annealing, efficiency of around 0.0002% was achieved. The main reason for the lower performance of the hybrid devices is due to the aggregation of the nanoparticles in the blend films, which was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements. In the following chapter, I will demonstrate the Bulk heterojunction organic photovoltaic approach by replacing the electron accepting nanoparticles with [6,6]-phenyl C61 butyric acid methyl ester (PCBM). A number of parameters in term of thickness, donor acceptor ratio of the materials and annealing temperatures were optimized. The results show that ESD devices performed rather well at lower temperature\ud
(below 130 0C) even better than the conventional spin coated sample with the same thickness and donor-acceptor ratio. At the optimum temperature of 1250C, the maximum power conversion efficiency (PCE) was 1.4 % for the spin coated samples, while ESD samples have higher PCE of 1.6 %. Further enhancement the PCE to 2.17% was observed in case of multilayered devices in which the active layer (P3HT:PCBM\ud
blend) is sandwiched between the very thin stacking layers of P3HT and PCBM.\ud
In the last part of the thesis, I focused on realizing the inverted OPV device architectures using ESD technique, where we replaced unstable hole transport layer poly(3,4-\ud
ethylenedioxythiophene) doped with polystyrene sulfonic acid (PEDOT:PSS) and Al metal contacts with TiOx/ZnO as electron extracting layers and MoO3/Ag as hole collecting contacts respectively. Long term stability and performance were compared to the direct architecture of OPV devices. The TiOx based inverted solar cell shows the maximum power conversion efficiency (PCE) of 1.30% from trilayer devices comparing to the PCE of 0.82% from single layer of the same materials at annealing temperature of 1100C for 10 minutes. Further improvement in device efficiency of inverted\ud
OPVs was demonstrated by employing ZnO electron collecting layers instead of TiOx which has better transparency and higher mobility. The power conversion efficiency (PCE) of 1.48% from the trilayer based OPV comparing to PCE of 0.83%\ud
from the single layer device at thermal annealing of 1200C was achieved. The stability of the inverted structure devices were tested under ambient condition with continuous\ud
illumination which shows much better device performance in longer time duration as compare to direct structure devices.\ud
In summary, application of ESD deposition for organic solar cells with different device configurations was systematically studied in this thesis and promising high efficiency and stability were obtained, even comparing to the common deposition method. This places the technique in a front position as an alternative method for organic thin film growth and device fabrication
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
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