1 |
Elaboration, caractérisation et modélisation optique d'électrodes transparentes intégrant des nanofils d'Ag pour des applications solaires / Elaboration, caracterization and optical modelling of transparent electrodes imbeddeing silver nanowires for solar applicationsChalh, Malika 05 June 2018 (has links)
Les électrodes transparentes sont intégrées dans de nombreux dispositifs optoélectroniques tels que (les OLED, les cellules photovoltaïques, les écrans tactiles...). De nos jours, l’électrode transparente la plus utilisée est l’oxyde d’indium dopé étain (ITO : Indium Tin Oxide) qui présente une transparence élevée et une faible résistance carrée. Malgré ces propriétés optoélectroniques exceptionnelles, l’ITO présente des inconvénients tels que la rareté de l’indium et sa fragilité qui est incompatible avec les substrats flexibles. Les nanofils d’argent (AgNWs) sont considérés comme une alternative potentielle pour remplacer l’ITO en vue de leur excellentes propriétés optoélectroniques et leur flexibilité. Néanmoins, les AgNWs souffrent de certains inconvénients (adhérence au substrat, rugosité). Dans ce travail nous proposons une structure de type Oxyde/Métal/Oxyde (OMO) en insérant une couche d’AgNWs comme couche métallique entre deux couches de nanoparticules d’oxydes (ZnO, AZO, WO3) pour fabriquer des électrodes tricouches de type ZAZ, AAA et WAW. Ces dernières ont montré transmission élevée combinée à une faible résistance carrée, ce qui leur permet d’être considérées comme des électrodes alternatives à l’ITO. De plus, les électrodes ZAZ et AAA ont été intégrées avec succès dans des cellules solaires organiques. En outre, un outil numérique potentiel utilisant la méthode FDTD (Finite Difference Time Domain) nous permis de confirmer les résultats expérimentaux pour les électrodes ZAZ. Ainsi, l’amélioration de l’absorption au sein de la couche active via l’effet plasmonique des AgNWs a été démontrée également. Finalement, nous avons pu modéliser un réseau semi-aléatoire des AgNWs inséré entre deux couches de ZnO tout en démontrant la différence en transmission entre une couche dense et une en nanoparticules de ZnO. / Transparent Electrodes (TEs) are crucial components of wide variety of optoelectronic devices as (OLEDs, photovoltaic cells, touch screen…). Nowadays, the transparent electrode widely used is Indium Tin Oxide (ITO), due to its good optoelectronic properties. However, it presents some drawbacks such as the indium scarcity and its brittleness which is not compatible with flexible substrates. Silver nanowires (AgNWs) were considered as potential alternative to replace ITO because of their good optical and electrical properties. Although promising, the AgNWs presents some drawbacks, including the poor adhesion to substrate and the surface roughness. In this work, we propose a sandwich structure Oxide/Metal/Oxide (OMO), where the metallic layer is based on AgNWs. We embedded AgNWs between two nanoparticles oxide layers of (ZnO, AZO, WO3) in order to fabricate trilayer electrodes which are ZAZ, AAA, WAW. These trilayer electrodes show a high transmittance and a low sheet resistance, which lead to consider them on of the alternative to the ITO. In addition, the ZAZ and AAA electrodes were successfully integrated in organic solar cells with good photovoltaic performance. Moreover, using the potential numerical method FDTD (Finite Difference Time Domain) we demonstrated a good agreement between the experimental and numerical results for the ZAZ electrodes. Therefore, the enhancement of absorption inside active layer due to the plasmonic effect of AgNWs was also demonstrated. Finally, we can model a randomly network of AgNWs embedded between two layers of ZnO, with investigating the difference between a dense and nanoparticles layer of ZnO.
|
2 |
"What More Could I Have Done?" A Graduate Student's Experience Teaching Writing About WritingHarper, Lena May 01 December 2017 (has links)
As writing about writing (WAW) research enters its "second wave," characterized not only by an increase in data-driven studies that theorize and assess the effectiveness of WAW curricula (Downs) but also by an increase in its prominence and adaptation, particularly among emerging writing studies scholars and teachers (e.g., Bird et al.), a space has opened for more and varied types of research, especially empirical research, to determine its effectiveness and to produce more solid recommendations for training and curriculum development, especially for those who are new to the field. This case study, which highlights how a novice teacher responds to a new teaching experience, aims to address the dearth of empirical research on WAW curricula and to aid other graduate instructors interested in teaching WAW or program administrators interested in implementing WAW. The study reports results from data collected (e.g., interviews, in-class observations, teachings logs) on the experience of a second-year MA graduate student in composition and rhetoric as he taught a WAW-based curriculum in a first-year composition (FYC) class in the beginning of 2016. His twenty students were also research subjects, but only a small portion of their data is reported here. The instructor's experience, chronicled in narrative form, began optimistically, though with a hint of skepticism, and ended in discouragement and even pessimism. These results were largely unexpected due to the instructor's confidence with and knowledge of WAW history, assumptions, and pedagogy and experience teaching FYC. However, his struggle with the approach reveals and confirms several important points for anyone hoping to teach or implement WAW. Particularly, new WAW instructors need sustained training, support, and mentoring to help them properly temper their expectations for the course, correctly and usefully interpret their experiences teaching WAW, successfully transfer prior teaching knowledge and methods to the WAW classroom, and ultimately find their place in WAW instruction.
|
3 |
"What More Could I Have Done?" A Graduate Student's Experience Teaching Writing About WritingHarper, Lena May 01 December 2017 (has links)
As writing about writing (WAW) research enters its second wave, characterized not only by an increase in data-driven studies that theorize and assess the effectiveness of WAW curricula (Downs) but also by an increase in its prominence and adaptation, particularly among emerging writing studies scholars and teachers (e.g., Bird et al.), a space has opened for more and varied types of research, especially empirical research, to determine its effectiveness and to produce more solid recommendations for training and curriculum development, especially for those who are new to the field. This case study, which highlights how a novice teacher responds to a new teaching experience, aims to address the dearth of empirical research on WAW curricula and to aid other graduate instructors interested in teaching WAW or program administrators interested in implementing WAW. The study reports results from data collected (e.g., interviews, in-class observations, teachings logs) on the experience of a second-year MA graduate student in composition and rhetoric as he taught a WAW-based curriculum in a first-year composition (FYC) class in the beginning of 2016. His twenty students were also research subjects, but only a small portion of their data is reported here. The instructors experience, chronicled in narrative form, began optimistically, though with a hint of skepticism, and ended in discouragement and even pessimism. These results were largely unexpected due to the instructors confidence with and knowledge of WAW history, assumptions, and pedagogy and experience teaching FYC. However, his struggle with the approach reveals and confirms several important points for anyone hoping to teach or implement WAW. Particularly, new WAW instructors need sustained training, support, and mentoring to help them properly temper their expectations for the course, correctly and usefully interpret their experiences teaching WAW, successfully transfer prior teaching knowledge and methods to the WAW classroom, and ultimately find their place in WAW instruction.
|
Page generated in 0.0201 seconds