1,720,955 research outputs found
Fabrication and characterization of hybrid polymer solar cell / Toong Way Yun
Get PDFThe easy fabrication method, tunable physical and chemical properties and cost-effective fabrication process, makes organic solar cells (OSC) very attractive in photovoltaic application. Nonetheless, the device performance is limited due to the low charge mobility of the organic semiconductors that results in a less efficient of charge transport to the respective electrodes. In order to address such problems, hybrid polymer solar cells based on bulk heterojunction (BHJ) structure, which composed of a combination of both organic and inorganic semiconductors are employed. However, the BHJ device performances are strongly dependent on good processing conditions, especially enhancement of photons absorption as well as the improvement of charge transport properties. Hence, the involved parameters and properties should be well optimized.
This dissertation describes the study of effects of blend composition and types of acceptor materials used on the optical, structural, morphological as well as the electrical properties of the three different hybrid BHJ systems. The hybrid materials consist of a blend of p-type conjugated polymer of poly(3-hexylthiophene) (P3HT) and n-type inorganic metal oxide nanoparticles, namely, zinc oxide (ZnO), titanium dioxide (TiO2) and yttrium oxide (Y2O3). The optical, structural and morphological characterizations of the blend thin films using UV-Visible absorption spectroscopy, X-ray diffraction (XRD) spectroscopy, Atomic Force Microscopy (AFM) and Field-effect Scanning Electron Microscopy (FESEM) are discussed. Furthermore, the co-relation of the thin film property with the device performance is presented. The results show that the device performance has been improved by optimizing the blend composition. This is due to an enhancement in light absorption in broader wavelength regime and improved charge transport through the formation of interpenetrating bicontinous pathway for the holes and electrons to reach the respective electrodes. These results are supported by the observation of the AFM and FESEM images of the increment in RMS roughness and formation of phase separation features in the blends. Besides, the well dispersion of inorganic nanoparticles over P3HT yields a larger interfacial area for charge carrier generation. Among the three hybrid systems investigated, P3HT:ZnO device performs the best with an optimal blend composition of 3% of ZnO nanoparticles in blend.
In order to further improve the device performances, ZnO sol-gel synthesis route has been utilized to produce a better mixing blend of P3HT and ZnO. Additionally, several approaches have been employed, namely modifying the sol content in blends, varying the annealing temperature, and inserting an additional ZnO buffer layer between the active layer and cathode. An optimal annealing treatment offers improved optical absorption properties and more uniform film surface morphology with eliminated redundant large pores and grain agglomerations. The role of the ZnO buffer layer in the blend system can be seen as an agent in facilitating the electron collection from the active layer to the cathode. The results indicate that the device efficiency has been improved by about 5 times for P3HT:ZnO sol gel device with optimized sol content (0.1ml sol), annealed at an optimized temperature of 100°C with additional ZnO buffer layer, compared to the P3HT:ZnO nanoparticles-based device
Fabrication and morphological characterization of hybrid polymeric solar cells based on P3HT and inorganic nanocrystal blends
No full textIn this research we investigated the effect of composition on the fabrication and morphological characteristics of a hybrid polymeric solar cell which consists of an electron donating conjugated polymer, namely is poly(3-hexylthiophene) (P3HT) combined with an electron-accepting component, which is a type of inorganic compound of TiO2 nanocrystals. The composition of TiO2 in the blends is varied and the optimum performance of the devices are studied. The optical and morphological characterizations are carried out via UV-Visible absorption spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The electrical characteristics of the devices are measured by using Keithley 2400 SMU and solar simulator with light intensity of 100 mW/cm2
Fabrication and morphological characterization of hybrid polymeric solar cells based on P3HT and inorganic nanocrystal blends
No full textIn this research we investigated the effect of composition on the fabrication and morphological characteristics of a hybrid polymeric solar cell which consists of an electron donating conjugated polymer, namely is poly(3-hexylthiophene) (P3HT) combined with an electron-accepting component, which is a type of inorganic compound of TiO2 nanocrystals. The composition of TiO2 in the blends is varied and the optimum performance of the devices are studied. The optical and morphological characterizations are carried out via UV-Visible absorption spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The electrical characteristics of the devices are measured by using Keithley 2400 SMU and solar simulator with light intensity of 100 mW/cm
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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