1,720,961 research outputs found
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
Interfacial Engineering for Carbon-Based All-Inorganic Perovskite Solar Cells
No full text1. Introduction||2. Experimental section of the general methods and characterization techniques||3. Reducing the energy loss by interface passivation via small molecule||4. Enhancing performance by sulfur-rich molecule interface engineering||5. Improving moisture stability via Cs2PtI6||6. General conclusions and future prospectsRecently, perovskite solar cells （PSCs） have attracted great attention because of their facile fabrication and excellent photovoltaic performance. So far, the power conversion efficiency （PCE） of PSCs has rapidly increased from 3.8 % to 25.5 %. All-inorganic perovskite materials, typically CsPbI2Br, have received widespread attention due to their illustrious thermal stability and appropriate bandgap. Furthermore, carbon-based CsPbI2Br perovskite solar cells not only further improve the thermal and moisture stability of the devices but also reduce production costs and simplify procedure processes. However, the inevitable defects of the perovskite layer, energy level mismatch between perovskite and carbon electrodes, and the phase instability of CsPbI2Br limit the enhancement of PCE and stability for carbon-based CsPbI2Br PSCs. This thesis focuses on improving the performance and stability of carbon-based all-inorganic PSCs through the interface modification method. Firstly, we used the N-phenylthiourea （PTU） and N-phenylurea （PU） with S or O elements and phenyl rings as modifiers of perovskite layers. The results show that either PTU or PU can promote the crystallinity of the perovskite film and effectively suppress the recombination of charge carriers. Secondly, we applied a small molecule material, delta-2:2-bis（1,3-dithiazole）, to modify the interface between perovskite and carbon electrode. We found that the sulfur atom of the target molecule （TM） can effectively interact with the Pb ion of perovskite, which can decrease the trap density of perovskite films and suppress the recombination. Thirdly, we introduced a double perovskite material, Cs2PtI6, to do the passivation of CsPbI2Br perovskite. We found that the fabricated device performance is improved, because the Cs2PtI6 can adjust the energy levels between the interfaces of the CsPbI2Br/carbon electrode and fill in the defects of perovskite surfaces and grain boundaries. As a result, the champion PCE of 13.69% was achieved after Cs2PtI6 introduction, the stability of the device was significantly improved under several conditions. In chapter 1, the progress and types of photovoltaic technology and the current development of the perovskite solar cells were introduced. In addition, the perovskite materials, the structure, and the working principle of the device also have been described. Moreover, the classification of perovskite solar cells and the advantages and disadvantages of all-inorganic perovskite solar cells were also introduced. Finally, the current issues of the carbon-based all inorganic perovskite solar cells and the purpose of this thesis were depicted. In chapter 2, the used reagents and apparatus in this thesis were listed. In addition, basic principles and techniques were described, such as XRD, FE-SEM, XPS, UV-Vis, UPS, SCLC, PL, and TRPL. Meanwhile, the information about the related equipment were also given. In chapter 3, for enhancing the performance and energy level match of the carbon-based all-inorganic PSCs. The N-phenylthiourea （PTU） with S atom and N-phenylurea （PU） with O atom were applied for interface modification materials in C-PSCs. The atoms S and O can combine with Pb and enhance perovskite crystallinity as well as manage the energy level. Meanwhile, after the passivation of PTU and PU, the defect state density of the perovskite layer is significantly reduced, thereby inhibiting the recombination of carriers. The Voc of the device with PTU increases from 1.12 V to 1.22V, 9% improvement over the control device. The efficiency of CsPbI2Br C-PSCs is improved from 10.29% to 13.01% after modification. Furthermore, the stability of the device has been improved. In chapter 4, for improved the performance of the devices, a sulfur-rich small molecule material （delta-2:2-bis （1,3-dithiazole））, was used to modify the interface between CsPbI2Br and carbon electrode. Encouragingly, the carbon-based CsPbI2Br PSCs achieve a high PCE of 13.78 % than the control of 10.40 %. The remarkable reduction of defect density and suppression recombination should be responsible for the PCE improvement. In chapter 5, for increased the PCE and stability of carbon-based CsPbI2Br PSCs. We demonstrate a simple and effective strategy for regulating energy level, inhibiting carrier recombination, and delaying the degradation of perovskite by modifying the surface of CsPbI2Br with a new type of 2D perovskite Cs2PtI6. The carbon-based CsPbI2Br PSCs achieve a higher PCE （13.69 %） than the control device （11.10 %）. The excellent matching of the energy level and suppression of charge carrier recombination should be responsible for the improvement of efficiency. Furthermore, the excellent hydrophobic performance of Cs2PtI6 enhances the moisture resistance of the device. Finally, the general conclusions of this thesis and the further prospects were summarized. In addition to efficiency, long-term stability and production cost still are issues that need to be overcome in the commercialization process of the PSCs. It is also the object that we will focus on in the future.九州工業大学博士学位論文 学位記番号: 生工博甲第429号 学位授与年月日: 令和4年3月25日令和3年
Interfacial Engineering for Carbon-Based All-Inorganic Perovskite Solar Cells
No full text九州工業大学博士学位論文（要旨）学位記番号：生工博甲第429号 学位授与年月日：令和4年3月25
炭素ベースの全無機ペロブスカイト太陽電池の界面エンジニアリング
Get PDF九州工業大学博士（工学）1. Introduction||2. Experimental section of the general methods and characterization techniques||3. Reducing the energy loss by interface passivation via small molecule||4. Enhancing performance by sulfur-rich molecule interface engineering||5. Improving moisture stability via Cs2PtI6||6. General conclusions and future prospectsRecently, perovskite solar cells （PSCs） have attracted great attention because of their facile fabrication and excellent photovoltaic performance. So far, the power conversion efficiency （PCE） of PSCs has rapidly increased from 3.8 % to 25.5 %. All-inorganic perovskite materials, typically CsPbI2Br, have received widespread attention due to their illustrious thermal stability and appropriate bandgap. Furthermore, carbon-based CsPbI2Br perovskite solar cells not only further improve the thermal and moisture stability of the devices but also reduce production costs and simplify procedure processes. However, the inevitable defects of the perovskite layer, energy level mismatch between perovskite and carbon electrodes, and the phase instability of CsPbI2Br limit the enhancement of PCE and stability for carbon-based CsPbI2Br PSCs. This thesis focuses on improving the performance and stability of carbon-based all-inorganic PSCs through the interface modification method. Firstly, we used the N-phenylthiourea （PTU） and N-phenylurea （PU） with S or O elements and phenyl rings as modifiers of perovskite layers. The results show that either PTU or PU can promote the crystallinity of the perovskite film and effectively suppress the recombination of charge carriers. Secondly, we applied a small molecule material, delta-2:2-bis（1,3-dithiazole）, to modify the interface between perovskite and carbon electrode. We found that the sulfur atom of the target molecule （TM） can effectively interact with the Pb ion of perovskite, which can decrease the trap density of perovskite films and suppress the recombination. Thirdly, we introduced a double perovskite material, Cs2PtI6, to do the passivation of CsPbI2Br perovskite. We found that the fabricated device performance is improved, because the Cs2PtI6 can adjust the energy levels between the interfaces of the CsPbI2Br/carbon electrode and fill in the defects of perovskite surfaces and grain boundaries. As a result, the champion PCE of 13.69% was achieved after Cs2PtI6 introduction, the stability of the device was significantly improved under several conditions. In chapter 1, the progress and types of photovoltaic technology and the current development of the perovskite solar cells were introduced. In addition, the perovskite materials, the structure, and the working principle of the device also have been described. Moreover, the classification of perovskite solar cells and the advantages and disadvantages of all-inorganic perovskite solar cells were also introduced. Finally, the current issues of the carbon-based all inorganic perovskite solar cells and the purpose of this thesis were depicted. In chapter 2, the used reagents and apparatus in this thesis were listed. In addition, basic principles and techniques were described, such as XRD, FE-SEM, XPS, UV-Vis, UPS, SCLC, PL, and TRPL. Meanwhile, the information about the related equipment were also given. In chapter 3, for enhancing the performance and energy level match of the carbon-based all-inorganic PSCs. The N-phenylthiourea （PTU） with S atom and N-phenylurea （PU） with O atom were applied for interface modification materials in C-PSCs. The atoms S and O can combine with Pb and enhance perovskite crystallinity as well as manage the energy level. Meanwhile, after the passivation of PTU and PU, the defect state density of the perovskite layer is significantly reduced, thereby inhibiting the recombination of carriers. The Voc of the device with PTU increases from 1.12 V to 1.22V, 9% improvement over the control device. The efficiency of CsPbI2Br C-PSCs is improved from 10.29% to 13.01% after modification. Furthermore, the stability of the device has been improved. In chapter 4, for improved the performance of the devices, a sulfur-rich small molecule material （delta-2:2-bis （1,3-dithiazole））, was used to modify the interface between CsPbI2Br and carbon electrode. Encouragingly, the carbon-based CsPbI2Br PSCs achieve a high PCE of 13.78 % than the control of 10.40 %. The remarkable reduction of defect density and suppression recombination should be responsible for the PCE improvement. In chapter 5, for increased the PCE and stability of carbon-based CsPbI2Br PSCs. We demonstrate a simple and effective strategy for regulating energy level, inhibiting carrier recombination, and delaying the degradation of perovskite by modifying the surface of CsPbI2Br with a new type of 2D perovskite Cs2PtI6. The carbon-based CsPbI2Br PSCs achieve a higher PCE （13.69 %） than the control device （11.10 %）. The excellent matching of the energy level and suppression of charge carrier recombination should be responsible for the improvement of efficiency. Furthermore, the excellent hydrophobic performance of Cs2PtI6 enhances the moisture resistance of the device. Finally, the general conclusions of this thesis and the further prospects were summarized. In addition to efficiency, long-term stability and production cost still are issues that need to be overcome in the commercialization process of the PSCs. It is also the object that we will focus on in the future.九州工業大学博士学位論文 学位記番号: 生工博甲第429号 学位授与年月日: 令和4年3月25日令和3年度doctoral thesi
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