1,721,023 research outputs found
CZTS layers for solar cells by an electrodeposition-annealing route
Get PDFIn the present work, Cu2ZnSnS4 (CZTS) thin films were successfully prepared using a co-electrodeposition–annealing route, in which Cu-Zn-Sn metal precursors were deposited by a novel electrolyte formula on Mo substrate, followed by annealing in elemental sulfur environment in quartz tube furnace with N2 atmosphere. Morphological, compositional and structural features of the films were investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction before and after sulfurization. Raman spectroscopy was performed after sulfurization to fully characterize the deposited films. Glow discharge optical emission spectroscopy (GDOES) has also been carried out to see
how composition changes along the film thickness. Results confirmed that kesterite structure of CZTS has been well formed after sulfurization of the film. It was also observed that CZTS properties depend on annealing times and ramping rate during sulfurization
CZTS absorber layer for thin film solar cells from electrodeposited metallic stacked precursors (Zn/Cu-Sn)
Get PDFIn the present work, Kesterite-Cu2ZnSnS4 (CZTS) thin films were successfully synthesized from stacked bilayer precursor (Zn/Cu-Sn) through electrodeposition-annealing route. Adherent and homogeneous Cu-poor, Zn-rich stacked metal Cu-Zn-Sn precursors with different compositions were sequentially electrodeposited, in the order of Zn/Cu-Sn onto Mo foil substrates. Subsequently, stacked layers were soft annealed at 350 °C for 20 min in flowing N2 atmosphere in order to improve intermixing of the elements. Then, sulfurization was completed at 585 °C for 15 min in elemental sulfur environment in a quartz tube furnace with N2 atmosphere. Morphological, compositional and structural properties of the films were investigated using SEM, EDS and XRD methods. Raman spectroscopy with two different excitation lines (514.5 and 785 nm), has been carried out on the sulfurized films in order to fully characterize the CZTS phase. Higher excitation wavelength showed more secondary phases, but with low intensities. Glow discharge optical emission spectroscopy (GDOES) has also been performed on films showing well formed Kesterite CZTS along the film thickness as compositions of the elements do not change along the thickness. In order to investigate the electronic structure of the CZTS, Photoluminescence (PL) spectroscopy has been carried out on the films, whose results matched up with the literatures
CZTS absorber layer for solar cells by electrodeposition annealing route using stacked precursors
No full textLAUREA MAGISTRALEPer via dell’ampia disponibilità, il basso costo e la non tossicità dei loro costituenti, le celle solari a film sottile basate su Cu2ZnSnS4 (CZTS) vengono considerate come uno strato assorbente alternativo ad altri dispositivi fotovoltaici ad esempio Cu(In,Ga)Se, CdTe, a-Si. Il CZTS ha promettenti proprieta ottiche: presenta un gap energetico di 1.5-1.6 eV e un ampio coefficiente di assorbimento dell’ordine di 104 -105 cm-1.
Lo scopo di questa tesi è produrre, con un approccio innovativo, una struttura di kesterite-CZTS come strato assorbente per celle solari a film sottile in un rapporto elementale che sia efficiente tra i componenti di Cu-Zn-Sn-S e su un substrato laminare di Mo. Per la produzione del CTZS è stato svolto un processo in tre stadi, comprendente elettrodeposizione a T ambiente, pre-annealing a 350°C per 20 minuti e sulfurizzazione a 350°C per 15 minuti. Lo stesso processo di elettrodeposizione è stato svolto in due stadi: nel primo stadio Cu-Sn è stato co-elettrodepositato da elettrolita acido (pH= 1.1) e successivamente uno strato di Zn è stato elettrodepositato su uno strato di Cu-Sn da una differente soluzione elettrolitica acida (pH= 5.5). Ognuno degli strati deposti era aderente, omogeneo e densamente impaccato.
Sono state applicate differenti tecniche quali XRF, XRD, SEM/EDS, RAMAN e GDOES per garantire che la fase di kesterite-CZTS si formasse secondo rapporti stechiometrici voluti. Le analisi XRD sono state svolte per analizzare le possibili fasi formate dopo ogni step di fabbricazione; la formazione di intermixing tra Cu-Zn-Sn è stata ottenuta con la formazione di Cu6Sn5 e Cu5Zn8 dopo annealing a basse temperature per permettere non solo l’incremento della cristallinità del film sulforizzato ma anche una diminuzione dei tempi di sulfurizzazione. La spettroscopia Raman è stata svolta per poter distinguere le possibili formazioni di seconde fasi nella kesterite-CZTS dopo sulforizzazione dove le analisi XRD non riescono a distinguerle; sono state osservate diverse seconde fasi, quali ZnS, Cu2SnS3 e Cu2-xS. Analisi SEM/EDS sono state effettuate per conoscere la morfologia superficiale e la composizione del precursore e dei film sulforizzati. È stata osservata una perdita di Zn durante il processo di sulforizzazione quindi è stato necessario usare precursori ricchi di zinco prima della sulforizzazione. Le analisi GDOES hanno mostrato che la distribuzione di composizione nello spessore del film è quasi stabile. Tutti i risultati delle caratterizzazioni hanno mostrato che la kesterize-CZTS si è formata con un buon rapporto stechiometrico.Cu2ZnSnS4 (CZTS)–based thin film solar cells have been considered as an alternative absorber layer to other thin film photovoltaic devices such as Cu(In,Ga)Se, CdTe, a-Si due to their earth-abundant, low cost and non-toxic constituents. The CZTS has promising optical properties; with a bandgap energy 1.5-1.6 eV and large absorption coefficient with an order of 104 -105 cm-1.
The aim of this study is to fabricate kesterite-CZTS as an absorber layer for thin film solar cells with an efficient elemental ratio among components of Cu-Zn-Sn-S on Mo foil substrate with a novel approach. For the fabrication of CZTS, a three-step process including electrodeposition at room temperature, pre-annealing at 350 0C for 20 min and sulfurization at 585 0C for 15 min were performed. The electrodeposition process itself was performed in two steps; in the first step Cu-Sn was co-electrodeposited from acidic electrolyte (pH=1.1) and later, Zn layer was electrodeposited on Cu-Sn layer from another acidic electrolyte (pH=5.5). Each of electrodeposited layers were adherent, homogeneous and densely packed.
Different characterization techniques like XRF, XRD, SEM/EDS, RAMAN and GDOES have been applied to make sure that kesterite-CZTS phase forms in a stoichiometric way. XRD was performed to analyze the possible phases after each step of fabrication; intermixing of Cu-Zn-Sn were succeeded with the formation of Cu6Sn5 and Cu5Zn8 after soft-annealing step which then not only increase the crystallinity of the sulfurized film, also allows to lower the sulfurization time. Raman spectroscopy was carried out to distinguish the possible secondary phases in kesterite-CZTS after sulfurization process where XRD fails to distinguish them; more secondary phases like ZnS, Cu2SnS3 and Cu2-xS were detected with Raman studies. SEM/EDS was performed to understand the surface morphology and composition of the precursor and sulfurized films. It has been observed that, Zn-loss occurs during sulfurization process and it is necessary to prepare zinc-rich precursors before sulfurization. GDOES analysis exhibits that composition distribution along the film was homogeneous and did not change that much. All characterization results confirmed that, kesterite-CZTS formed within a good stoichiometric ratio
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
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