Characteristics of thin films fabricated by spray coating on rough and permeable paper substrates / Fatemeh Zabihi in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 12, N° 3 (05/2015)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 12, N° 3 (05/2015) . - p. 489-503 Titre : Characteristics of thin films fabricated by spray coating on rough and permeable paper substrates Type de document : texte imprimé Auteurs : Fatemeh Zabihi, Auteur ; Morteza Eslamian, Auteur Année de publication : 2015 Article en page(s) : p. 489-503 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Couches minces Papier Photopiles Revêtements Système de pulvérisation (technologie) Index. décimale : 667.9 Revêtements et enduits Résumé : This work presents the results of simple but effective experiments designed and performed to study the characteristics of coatings made by air-assist spray deposition of a food-dye solution on regular printer and glossy papers, with different surface roughness and porosity. The objective of this work is twofold: First, the colorful nature of coatings made it possible to visualize spray patterns and coverage using an optical microscope and image analysis software, although detailed analysis of film roughness, thickness, and morphology was also performed using sophisticated characterization tools, such as confocal laser scanning microscopy, scanning electron microscopy, and atomic force microscopy. These results help in understanding the effect of processing parameters on spray coating on rough surfaces, such as already spray-coated solar cell films in a stacked thin film solar cell device. The underneath spray-on layers (such as a buffer layer underneath the active layer in a polymer solar cell) are usually rough. Paper substrate resembles such rough surfaces. Second, our results can provide insight into the feasibility of using paper substrates to fabricate paper-based photovoltaic solar cells. Effects of substrate type (wetting, porosity, and roughness), substrate temperature, spray nozzle travel speed over the substrate, precursor solution flow rate, and the number of spray passes are studied on coating characteristics. A novel approach is also employed to improve the coating characteristics via imposing ultrasonic vibration to the paper substrates, where the vibration results in a significant improvement in all coating indices. Note de contenu : - Effect of nozzle tip speed and solution precursor flow rate - Effect of the number of spray passes - Effect of substrate temperature - Effect of substrate type - Effect of substrate vibration DOI : 10.1007/s11998-015-9656-5 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-015-9656-5.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24173 [article]

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Controlled wetting/dewetting through substrate vibration-assisted spray coating (SVASC) / M. Habibi in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 13, N° 2 (03/2016)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 13, N° 2 (03/2016) . - p. 211-225 Titre : Controlled wetting/dewetting through substrate vibration-assisted spray coating (SVASC) Type de document : texte imprimé Auteurs : M. Habibi, Auteur ; Morteza Eslamian, Auteur ; F. Soltani-Kordshuli, Auteur ; Fatemeh Zabihi, Auteur Année de publication : 2016 Article en page(s) : p. 211-225 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Démouillage (chimie des surfaces) Dépôt par pulvérisation Mouillage (chimie des surfaces) Pérovskite Photopiles Poly(3,4-éthylènedioxythiophène) Polystyrène sulfone Ultrasons Vibrations (mécanique) Index. décimale : 667.9 Revêtements et enduits Résumé : We have recently developed a novel spray-coating method, called the “substrate vibration-assisted spray coating” (SVASC) (Zabihi and Eslamian in J Coat Technol Res 12:711–719, 2015), in which ultrasonic vibration is imposed on the substrate to improve the spray-on film and coating characteristics. In that work, the SVASC method was introduced, and its effectiveness on the uniformity and electrical conductivity of PEDOT:PSS films, used in emerging solar cells, was demonstrated. The present work reports unprecedented results on the effect of the ultrasonic vibration power on wetting/dewetting of PEDOT:PSS films. It is observed that, while the application of a low-power ultrasonic vibration (LPUV) improves the surface wetting and film coverage through improving droplet spreading and coalescence and repairing of the dewetted areas, a high-power ultrasonic vibration (HPUV) promotes dewetting, resulting in less coverage and the formation of a nonuniform film. The improved wetting due to the application of the LPUV has opened a window of opportunity for the fabrication of intact thin films and related thin film devices. On the other hand, the controlled dewetting process due to the application of the HPUV may have novel applications in template fabrication and self-assembly in nanotechnology. Here, we also study the effects of the application of multipass spraying compared with single-pass spraying strategy, and the application of using two co-solvents on PEDOT:PSS film characteristics. The results confirm that the utilization of isopropyl alcohol (IPA) as a co-solvent added to the PEDOT:PSS precursor solution improves the surface wettability and film coverage, compared to the films made using demethylformamide (DMF), as the co-solvent. DOI : 10.1007/s11998-015-9748-2 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-015-9748-2.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26107 [article]

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Development of multiple-droplet drop-casting method for the fabrication of coatings and thin solid films / Morteza Eslamian in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 15, N° 2 (03/2018)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 15, N° 2 (03/2018) . - p. 271-280 Titre : Development of multiple-droplet drop-casting method for the fabrication of coatings and thin solid films Type de document : texte imprimé Auteurs : Morteza Eslamian, Auteur ; Firuze Soltani-Kordshuli, Auteur Année de publication : 2018 Article en page(s) : p. 271-280 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Couches minces Dépôt par pulvérisation Gouttelettes Poly(3,4-éthylènedioxythiophène) Polystyrène sulfone Revêtements organiques Ultrasons Vibrations (mécanique) Index. décimale : 667.9 Revêtements et enduits Résumé : Spray coating is a commercial and low-cost technique for the fabrication of large-area coatings and thin films, but it is a stochastic process that is hard to control, as far as the fabrication of thin coatings and solid films is concerned. On the other hand, drop-casting is a facile and more controllable coating technique than spray coating, but its application is limited to small-area thin solid films and coatings. The objective of this work is, therefore, to study the feasibility of impinging an array of droplets, rather than just one droplet, to fabricate polymeric and other solution-processed thin films with larger surface areas than those produced by conventional drop-casting. To this end, in this study, four droplets of poly(3,4-ethylenedioxythiophene)–polystyrene sulfonate (PEDOT:PSS) solution are released simultaneously and impinged on the four vertices of a square on a wettable solid surface to make a thin film. The effect of the substrate texture on the spreading and the film formation process is studied. As a novel idea, the substrate is excited by ultrasonic vibration to improve the droplet spreading and coalescence. It is shown that as time elapses, the impinged droplets successfully coalesce and make a thin film. Surface morphology and roughness of the resulting PEDOT:PSS thin solid films show that, except on the edges, the resulting thin solid films are uniform. This leads us to conclude that the application of equal-sized and equally-spaced multiple droplets released simultaneously and impinged on vibrating substrates could be considered as a new coating technique, which has some of the benefits of the spray coating, but it is much more controllable than spray coating. DOI : 10.1007/s11998-017-9975-9 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-017-9975-9.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30279 [article]

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Performance enhancement of large-area graphene–polymer flexible transparent conductive films fabricated by ultrasonic substrate vibration-assisted rod coating / Zhi Li in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 16, N° 6 (11/2019)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 16, N° 6 (11/2019) . - p. 1773-1780 Titre : Performance enhancement of large-area graphene–polymer flexible transparent conductive films fabricated by ultrasonic substrate vibration-assisted rod coating Type de document : texte imprimé Auteurs : Zhi Li, Auteur ; Xinyu Zhang, Auteur ; Long Shen, Auteur ; Zhijun Fan, Auteur ; Xuewen Chen, Auteur ; Min Chen, Auteur ; Shaohua Qin, Auteur ; Fatemeh Zabihi, Auteur ; Morteza Eslamian, Auteur ; Qianli Chen, Auteur Année de publication : 2019 Article en page(s) : p. 1773-1780 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Composites Conducteurs organiques Electrodes Electronique -- Matériaux Graphène Le graphène est un cristal bidimensionnel (monoplan) de carbone dont l'empilement constitue le graphite. Il a été isolé en 2004 par Andre Geim, du département de physique de l'université de Manchester, qui a reçu pour cette découverte le prix Nobel de physique en 2010 avec Konstantin Novoselov. Il peut être produit de deux manières : par extraction mécanique du graphite (graphène exfolié) dont la technique a été mise au point en 2004, ou par chauffage d'un cristal de carbure de silicium, qui permet la libération des atomes de silicium (graphène epitaxié). Record en conduction thermique jusqu'à 5300 W.m-1.K-1. C'est aussi un matériaux conducteur. Poly(3,4-éthylènedioxythiophène) Polystyrène sulfone Revêtements organiques Transparence (optique) Ultrasons Index. décimale : 667.9 Revêtements et enduits Résumé : The graphene/PEDOT:PSS composite thin films (GCFs) are promising candidates for transparent conductive electrodes in low-cost flexible thin-film devices, which can be applied in portable and flexible electronic devices such as organic light-emitting diodes and organic solar cells. In this work, to improve the film characteristics, we impose ultrasonic vibration on the substrate, and therefore the wet coating, during the rod-coating preparation process of the GCFs, and study the effect of vibration power. The 5 x 5 cm2 thin films prepared on flexible polyethylene terephthalate with ultrasonic vibration imposed on the substrate of wet films demonstrate improved conductivity and reduced thickness. Ninefold enhancement in charge carrier concentration is observed when ultrasonic vibration is applied. The improved performance is ascribed to the eliminated pores in films, and rearrangement of graphene in the polymer network, brought about by nanometer-scale-amplitude ultrasonic vibrations. The electrical property of flexible films is demonstrated to be stable after multiple cycles of bending. Note de contenu : - Film preparation - Characterization DOI : 10.1007/s11998-019-00265-8 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-019-00265-8.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33431 [article]

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Substrate vibration-assisted spray coating (SVASC) : significant improvement in nano-structure, uniformity, and conductivity of PEDOT:PSS thin films for organic solar cells / Fatemeh Zahibi in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 12, N° 4 (07/2015)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 12, N° 4 (07/2015) . - p. 711-719 Titre : Substrate vibration-assisted spray coating (SVASC) : significant improvement in nano-structure, uniformity, and conductivity of PEDOT:PSS thin films for organic solar cells Type de document : texte imprimé Auteurs : Fatemeh Zahibi, Auteur ; Morteza Eslamian, Auteur Année de publication : 2015 Article en page(s) : p. 711-719 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Couches minces Dépôt par pulvérisation Photopiles Poly(3,4-éthylènedioxythiophène) Polystyrène sulfone Revêtements:Peinture Ultrasons Index. décimale : 667.9 Revêtements et enduits Résumé : In an attempt to improve surface wetting and coating characteristics, a novel technique, i.e., imposing ultrasonic vibration on the substrate, is introduced. This technique is combined with conventional ultrasonic spray coating, thus substrate vibration-assisted spray coating (SVASC), and is employed to fabricate PEDOT:PSS thin films. PEDOT:PSS is a co-polymer, commonly used as solar cell buffer layers and thin-film electrodes. Advanced surface characterization techniques, such as atomic force microscopy and confocal laser scanning microscopy are utilized. The results show that the application of the imposed vibration on the substrate results in a significant decrease in surface roughness, film thickness, and the number of defects and pin-holes. In terms of the film functionality, the electrical conductivity of the PEDOT:PSS films made using the SVASC technique shows a four-time increase, compared to those made by conventional ultrasonic spray coating. In conventional ultrasonic spray coating, increasing the number of spray passes or deposition layers usually improves the coating uniformity. For aqueous PEDOT:PSS solution and within the range of the values of the parameters investigated in this work, with imposed substrate vibration, the number of spray passes is immaterial, as far as the film uniformity is concerned. However, the application of multiple spray passes enhances the film’s electrical conductivity. Our unprecedented results on the combined substrate vibration with spray coating provide a platform for low-cost fabrication of solution-processed thin-film solar cell devices, and a forward step toward commercialization of emerging solar cells, such as polymer and perovskite solar cells. The positive effect of using imposed substrate vibration on spray-on solar cell thin films may be deployed in other coating (e.g., spin coating) and spray coating applications as well. DOI : 10.1007/s11998-015-9682-3 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-015-9682-3.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24405 [article]

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