1,720,956 research outputs found
Reversible and irreversible degradation of perovskite solar cells: Under light dark cycling
No full textThe perovskite solar cells (PSCs) comfortably placed close to the top of record power conversion efficiency chart for lab scale solar cells is not sold in the market. Yes, this statement can be a dictionary example for the word 'oxymoron'. Even with improving efficiencies recorded every now and then and with good material properties for a good solar cell, the PSCs are not commercialized due to their instability in performance. PSCs often show an irreversible degradation under long term continuous illumination. However, in real life solar cells naturally undergo light dark cycling over day night periods. Therefore, in this work we have systematically investigated PSCs’ behavior through such light dark cycling. It is observed when the cell temperature stays constant under light, the efficiency of PSCs slightly decreases during daytime but fully recovers after a night’s rest in dark. In contrast, if the cell experiences temperature variation under light, which is more realistic for outdoor conditions, even after rest in night, the efficiency does not fully recover. To explain these observations, a hypothesis relating the ionic defect generation and migration to the change of built in field across light dark cycling is proposed. This work suggests it’s vital to avoid irreversible PSC degradation by undermining defects formation and migration.Electrical Engineering | Sustainable Energy Technolog
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
Multifaceted Characterization Methodology for Understanding Nonidealities in Perovskite Solar Cells: A Passivation Case Study
No full textA multifaceted characterization approach is proposed, aiming to establish a link between nanoscale electrical properties and macroscale device characteristics. Current-voltage (I-V) measurements are combined with admittance spectroscopy (AS) and deep-level transient spectroscopy (DLTS) for the analysis of charge-related performance losses with time-of-flight secondary-ion mass spectrometry to complete the understanding of ionic motion in the device. This is applied to the study of surface treatment in perovskite solar cells, which implements several strategies to improve band alignment, perovskite grain growth, and chemical passivation. An increase of both open-circuit voltage (Voc) and fill factor of respectively 90 mV and 11% is shown after surface treatment, with an absolute efficiency increase of 4%. AS measurements, coupled with a lumped elements model, rule out the impact of transport layers as the origin of the performance improvement, rather pointing toward a reduction in ionic resistance in the perovskite bulk. Analysis of the DLTS response yields an activation energy of 0.41 eV, which is likely related to the same ionic mechanism discovered with AS. Finally, both of these techniques enable to show that the surface treatment main contribution is to reduce ion-related recombination of charge carriers. Characterization is used for the study of surface treatment in perovskite solar cells. Current-voltage measurements show a 90 mV increase in open-circuit voltage, 11 % increase in fill-factor and 4 % increase in efficiency. Capacitance-based measurements show an increase in ionic resistance in the perovskite bulk and an activation energy of 0.41 eV, pointing toward a reduction in ion-assisted charge carrier recombination.image (c) 2024 WILEY-VCH GmbHThe authors and especially J.P. would like to thank Leonardo Kopprio, Pilar Lopez, Jean-Paul Kleider, and Jose Alvarez from CNRS/IPVF, as well as Christoph Messmer and Jonas Schoen from Fraunhofer ISE/InaTech for the interesting discussions around admittance spectroscopy simulations. They would also like to thank Nico Fransaert and Aslihan Babayigit from the University of Hasselt for their help regarding the interpretation of time-of-flight secondary-ion mass spectrometry results. The authors are indebted to the two reviewers for their helpful comments and suggestions. The authors want to acknowledge funding from the TRIUMPH Horizon Europe project, with grant agreement ID: 101075725, and from the Special Research Fund of Hasselt University, with no. BOF22OWB15
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