1,720,966 research outputs found
Synthesis of organic ionic compounds and their investigation as possible hole transporting materials.
No full textThe gradual depletion of Earth's natural resources and the worlds growing energy needs has turned energy saving technology development into one of the greatest science challenges of today. Considering that it shouldn’t be odd that more and more scientist are interested in the renewable energy, for example solar energy. Every second Sun outputs so much energy that it could satisfy the needs of humanity for roughly a million years. Such impressive data inspires scientist to create new devices which could convert this massive energy into electricity. That’s where solar cells come in handy and engineering meets chemistry, which is charged with a task of utmost importance – creating the next generation of materials fit for constructing such devices. Said devices often consist of several layers, each having a specific function and made of materials that meet a certain set of requirements. The main goal of this work was to synthesize new organic hole transporting materials (HTM). The main requirements for these p – type semiconductors are as follows: the ionization potential in the solid state must be within a defined range and high charge mobility. In the course of this work several new triphenylamine-based structures with ionic groups have been synthesized. Their thermal, optical and photoelectric properties have been measured and investigated. As the result the following conclusion has been made: attaching ionic groups to a triphenylamine-based compound affects their optical properties. However if we compare different ionic groups possessing derivative the change is rather small. Also different ions considerably affects ionic material thermal properties. It is believed that such changes occur due to the different nature of ions and their placement in space. The solid state ionization potentials of the synthesized HTMs are in the range between 5,3 and 5,4 eV, and glass transition temperatures go as high as 80°C. Such parameter values could allow the use of these materials in the construction of various optoelectronic devices
Perovskitiniams saulės elementams skirtos krūvį pernešančios medžiagos su difeniletenilo arba diazaaceno fragmentais.
No full textDuring more than a decade of research, many HTMs of various structures were developed for PSCs; however, most of them are expensive or require multi-step synthesis, or both. The two most commonly used materials as p-type semiconductors, spiro-MeOTAD and PTAA, are no exception to the rule. Furthermore, spiro-MeOTAD raises long-term stability concerns due to the dopants which are necessary to achieve great optoelectronic performance. Despite the aforementioned issues, PSCs scientific community seems to have stagnated on spiro-MeOTAD and PTAA as HTMs of choice while in the same time demanding cheaper, more efficient and more stable alternatives for commercial applications. In this PhD thesis, various HTMs have been designed and synthesized in hope to eliminate at least some flaws of the predominantly used p-type charge carriers
Organiniai piridinio ir ketvirtinio amonio dariniai: sintezė ir puslaidininkinių savybių tyrimas.
No full textThe gradual depletion of Earth's natural resources, the worlds growing energy needs and worldwide pollution, demands a new way of generating clean energy for mankind. Therefore, it should not come as a surprise, that renewable resources are now the most attractive option to replace fossil fuel. One of the most promising source of energy is the sun. It emits enough energy (in one minute around 1015W) to supply the entire worlds demand and attracts the attention of scientists around the world. To make use of such vast amount of energy solar cell devices are being used, but the technology behind it is rather complicated and costly
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
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