1,720,965 research outputs found
Performance Enhancement of Organic Solar Cells via Device Engineering and Their Future Potential Applications
Get PDFRenewable energy sources are promising long-term solution to solve the energy supply crisis due to the excessive use of non-renewable fossil fuels. One of the options is solar energy, which can be harvested directly from sunlight using photovoltaic (PV) technology. In recent years, organic solar cells (OSCs) as the building blocks of organic PV technology have emerged in the PV field, enabling the realization of environmental-friendly and low-cost PV technology. However, issues related to efficiency performance still posed a major setback to commercialization of OSCs. In view of this, this study is conducted to present comprehensive understandings on how OSCs’ performance in terms of optical, electrical, morphological and mechanical properties can be improved through device engineering strategy (interface and electrode engineering strategy). In addition, the potential applications of OSCs achieved via device engineering strategy are also being explored. In summary, the studies conducted can be divided into three main parts.
The first part focuses on improving OSCs’ performance through interface engineering strategy for the realization of high-performing OSCs. Interface engineering on sol-gel zinc oxide (ZnO) electron-transporting layer (ETL) was conducted by introducing additional oxadiazole-based electron-transporting material called 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) between ZnO ETL and photoactive layer. The significance of incorporating PBD on ZnO was demonstrated by investigating the change in optical, electrical and morphological properties of pristine ZnO ETL. The findings shown that additional PBD layer could improve pristine ZnO film’s conductivity, create better energy level alignment with the photoactive layer, smoothen ZnO film’s morphology and improve ZnO film’s hydrophobicity. All those factors crucially influenced the charge extraction, transport and recombination processes in OSCs, which were conducive for the enhancement in photovoltaic performance of ZnO/PBD-based device. In fact, through interface engineering strategy, inverted OSCs based on poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] (PBDB-T donor) and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6/7-methyl)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (IT-M acceptor) could demonstrate ~7% increment in the photovoltaic performance from 10.8% (ZnO-based device) to 11.6% (ZnO/PBD-based device).
The second part focuses on improving OSCs’ performance through electrode engineering strategy for the realization of high-performing flexible OSCs. Electrode engineering on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) electrode was conducted by utilizing polyhydroxy compound dopant and gentle acid post-treatment method, specifically xylitol dopant and methanesulfonic acid (MSA) treatment. The significance of xylitol dopant and MSA treatment on PEDOT:PSS electrode was demonstrated by investigating the change in optical, electrical, morphological and mechanical properties of pristine PEDOT:PSS electrode. The findings shown that both doping and acid treatment on PEDOT:PSS electrode could improve the optical transparency of electrode, enhance electrode’s conductivity and modify electrode’s morphology. In addition, such treatment could also provide electrode a stronger adhesion ability with the substrate, which were effective for improving the mechanical stability of electrode against extreme mechanical deformation. All those factors promoted the realization of high-performing flexible OSCs based on PEDOT:PSS electrode. In fact, through electrode engineering strategy, conventional OSCs based on poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] (PBDB-T-2F/PM6 donor) and 2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2",3’':4’,5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (BTP-4F/Y6 acceptor) could demonstrate an excellent photovoltaic performance of 14.2% with remarkable mechanical robustness against bending and folding.
The last part focuses on the application of device engineering, specifically electrode engineering as a continuation of study from the previous part. The desirable mechanical and optical properties of the engineered PEDOT:PSS could make PEDOT:PSS a great candidate for usage in foldable-flexible semi-transparent OSCs (FST-OSCs). FST-OSCs were fabricated similarly using engineered PEDOT:PSS electrode and PBDB-T-2F:Y6 photoactive layer system. As a result, high-performing FST-OSCs with over 10% efficiency and 21% average visible light transmittance, as well as excellent mechanical stability were obtained. The potential of such FST-OSCs for greenhouse application was investigated by incorporating them as part of roofs in the simulated greenhouse. Comparisons between plants grown under direct sunlight with FST-OSCs roof and those under direct sunlight yielded remarkably similar results in terms of branch sturdiness and hypertrophic leaves, proving the significance of electrode engineering strategy in realizing high-performing FST-OSCs for practical greenhouse applications
Performance Enhancement of Organic Solar Cells via Device Engineering and Their Future Potential Applications
Get PDFRenewable energy sources are promising long-term solution to solve the energy supply crisis due to the excessive use of non-renewable fossil fuels. One of the options is solar energy, which can be harvested directly from sunlight using photovoltaic (PV) technology. In recent years, organic solar cells (OSCs) as the building blocks of organic PV technology have emerged in the PV field, enabling the realization of environmental-friendly and low-cost PV technology. However, issues related to efficiency performance still posed a major setback to commercialization of OSCs. In view of this, this study is conducted to present comprehensive understandings on how OSCs’ performance in terms of optical, electrical, morphological and mechanical properties can be improved through device engineering strategy (interface and electrode engineering strategy). In addition, the potential applications of OSCs achieved via device engineering strategy are also being explored. In summary, the studies conducted can be divided into three main parts.
The first part focuses on improving OSCs’ performance through interface engineering strategy for the realization of high-performing OSCs. Interface engineering on sol-gel zinc oxide (ZnO) electron-transporting layer (ETL) was conducted by introducing additional oxadiazole-based electron-transporting material called 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) between ZnO ETL and photoactive layer. The significance of incorporating PBD on ZnO was demonstrated by investigating the change in optical, electrical and morphological properties of pristine ZnO ETL. The findings shown that additional PBD layer could improve pristine ZnO film’s conductivity, create better energy level alignment with the photoactive layer, smoothen ZnO film’s morphology and improve ZnO film’s hydrophobicity. All those factors crucially influenced the charge extraction, transport and recombination processes in OSCs, which were conducive for the enhancement in photovoltaic performance of ZnO/PBD-based device. In fact, through interface engineering strategy, inverted OSCs based on poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] (PBDB-T donor) and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6/7-methyl)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (IT-M acceptor) could demonstrate ~7% increment in the photovoltaic performance from 10.8% (ZnO-based device) to 11.6% (ZnO/PBD-based device).
The second part focuses on improving OSCs’ performance through electrode engineering strategy for the realization of high-performing flexible OSCs. Electrode engineering on poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) electrode was conducted by utilizing polyhydroxy compound dopant and gentle acid post-treatment method, specifically xylitol dopant and methanesulfonic acid (MSA) treatment. The significance of xylitol dopant and MSA treatment on PEDOT:PSS electrode was demonstrated by investigating the change in optical, electrical, morphological and mechanical properties of pristine PEDOT:PSS electrode. The findings shown that both doping and acid treatment on PEDOT:PSS electrode could improve the optical transparency of electrode, enhance electrode’s conductivity and modify electrode’s morphology. In addition, such treatment could also provide electrode a stronger adhesion ability with the substrate, which were effective for improving the mechanical stability of electrode against extreme mechanical deformation. All those factors promoted the realization of high-performing flexible OSCs based on PEDOT:PSS electrode. In fact, through electrode engineering strategy, conventional OSCs based on poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] (PBDB-T-2F/PM6 donor) and 2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2",3’':4’,5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (BTP-4F/Y6 acceptor) could demonstrate an excellent photovoltaic performance of 14.2% with remarkable mechanical robustness against bending and folding.
The last part focuses on the application of device engineering, specifically electrode engineering as a continuation of study from the previous part. The desirable mechanical and optical properties of the engineered PEDOT:PSS could make PEDOT:PSS a great candidate for usage in foldable-flexible semi-transparent OSCs (FST-OSCs). FST-OSCs were fabricated similarly using engineered PEDOT:PSS electrode and PBDB-T-2F:Y6 photoactive layer system. As a result, high-performing FST-OSCs with over 10% efficiency and 21% average visible light transmittance, as well as excellent mechanical stability were obtained. The potential of such FST-OSCs for greenhouse application was investigated by incorporating them as part of roofs in the simulated greenhouse. Comparisons between plants grown under direct sunlight with FST-OSCs roof and those under direct sunlight yielded remarkably similar results in terms of branch sturdiness and hypertrophic leaves, proving the significance of electrode engineering strategy in realizing high-performing FST-OSCs for practical greenhouse applications
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
