33 research outputs found
Développement de barrières de perméation constituées de multicouches de nitrure de silicium déposées par la technique filament chaud pour les dispositifs organiques sur substrats flexibles
No full textEfficient gas-diffusion (permeation) barriers are needed for organic optoelectronic devices because the presence of moisture or oxygen can cause strong degradation. In order for these devices to operate continuously during a long term, so to be commercialized, a reliable flexible thin film encapsulation is required, which is a major challenge. Very low water vapor transmission rates of the order of 10-5 g/m2.day are required. To reach this goal two ways have been adopted: on one hand fabricating SiNx:H / SiNx:H multilayer barriers separated by a specific Ar plasma treatment, on the other hand fabricating the conventional inorganic/organic hybrid multilayer moisture barriers. We have chosen hot-wire chemical vapor deposition (HW-CVD) as the main technique for depositing the inorganic layers and a large part of our efforts has been devoted to the complete study of the parameters controlling the plasma treatment: the energy of the ions impinging the inorganic surfaces was crucial. Several analytical (morphological, structural, optical, electrical) techniques have been necessary to assess qualitatively and quantitatively the different layers composing the moisture barriers. A physical interpretation of the plasma process treatment has been given, based on the interface atomic rearrangements induced by the low energy ions (< 40 eV). For each way of encapsulation, we have obtained very low water vapor transmission rates (4 to 7 × 10-5 g/m2.day). Combining above two encapsulation methods, we have achieved extremely low WVTR rate (6 × 10-6 g/m2.day), which seems sufficient for the utilization of organic electronic devices.Les dispositifs optoélectroniques à base de matériaux organiques nécessitent la réalisation de couches barrière de perméation car l'oxygène et l'humidité dégradent fortement ces dispositifs. Afin d'augmenter leur durée de vie et ainsi les rendre commercialement attractifs, des couches d'encapsulation sont nécessaires, ceci représente un défi majeur surtout dans le cadre des substrats flexibles comme les plastiques. Des faibles valeurs du taux de perméation sont exigées, typiquement de l'ordre de 10-5 g/m2.jour dans le cadre de l'eau. Deux voies ont été étudiées, dans le cadre de cette thèse, pour atteindre cet objectif: d'une part en fabriquant des barrières multicouches à base de nitrure de silicium amorphe, chaque couche étant séparée de la suivante par un traitement plasma d'argon, d'autre part en fabriquant des barrières hybrides alternant des couches inorganiques avec des couches organiques. Nous avons choisi la technique de dépôt chimique en phase vapeur par filament chaud (HW-CVD) pour le dépôt des couches inorganiques et nos efforts ont porté sur l'étude approfondie des paramètres contrôlant le plasma. Il ressort que l'énergie des ions impactant la surface a été le paramètre déterminant. Diverses techniques d'analyse ont été nécessaires pour évaluer précisément la qualité des couches constituant les barrières de perméation. Une interprétation physique du procédé plasma a été proposée, basée sur le réarrangement atomique induit à chaque interface par les ions de faible énergie (< 40 eV). Pour chacune des voies choisies, des très faibles taux de perméation (4 à 7 × 10-5 g/m2.jour) ont été atteints. Avec la combinaison de ces deux méthodes d'encapsulation, nous avons atteint une valeur de WVTR extrêmement faible (6 × 10-6 g/m2.jour), ce qui semble suffisant pour l'utilisation dans des dispositifs organiques
Développement de barrières de perméation constituées de multicouches de nitrure de silicium déposées par la technique filament chaud pour les dispositifs organiques sur substrats flexibles
No full textEfficient gas-diffusion (permeation) barriers are needed for organic optoelectronic devices because the presence of moisture or oxygen can cause strong degradation. In order for these devices to operate continuously during a long term, so to be commercialized, a reliable flexible thin film encapsulation is required, which is a major challenge. Very low water vapor transmission rates of the order of 10-5 g/m2.day are required. To reach this goal two ways have been adopted: on one hand fabricating SiNx:H / SiNx:H multilayer barriers separated by a specific Ar plasma treatment, on the other hand fabricating the conventional inorganic/organic hybrid multilayer moisture barriers. We have chosen hot-wire chemical vapor deposition (HW-CVD) as the main technique for depositing the inorganic layers and a large part of our efforts has been devoted to the complete study of the parameters controlling the plasma treatment: the energy of the ions impinging the inorganic surfaces was crucial. Several analytical (morphological, structural, optical, electrical) techniques have been necessary to assess qualitatively and quantitatively the different layers composing the moisture barriers. A physical interpretation of the plasma process treatment has been given, based on the interface atomic rearrangements induced by the low energy ions (< 40 eV). For each way of encapsulation, we have obtained very low water vapor transmission rates (4 to 7 × 10-5 g/m2.day). Combining above two encapsulation methods, we have achieved extremely low WVTR rate (6 × 10-6 g/m2.day), which seems sufficient for the utilization of organic electronic devices.Les dispositifs optoélectroniques à base de matériaux organiques nécessitent la réalisation de couches barrière de perméation car l'oxygène et l'humidité dégradent fortement ces dispositifs. Afin d'augmenter leur durée de vie et ainsi les rendre commercialement attractifs, des couches d'encapsulation sont nécessaires, ceci représente un défi majeur surtout dans le cadre des substrats flexibles comme les plastiques. Des faibles valeurs du taux de perméation sont exigées, typiquement de l'ordre de 10-5 g/m2.jour dans le cadre de l'eau. Deux voies ont été étudiées, dans le cadre de cette thèse, pour atteindre cet objectif: d'une part en fabriquant des barrières multicouches à base de nitrure de silicium amorphe, chaque couche étant séparée de la suivante par un traitement plasma d'argon, d'autre part en fabriquant des barrières hybrides alternant des couches inorganiques avec des couches organiques. Nous avons choisi la technique de dépôt chimique en phase vapeur par filament chaud (HW-CVD) pour le dépôt des couches inorganiques et nos efforts ont porté sur l'étude approfondie des paramètres contrôlant le plasma. Il ressort que l'énergie des ions impactant la surface a été le paramètre déterminant. Diverses techniques d'analyse ont été nécessaires pour évaluer précisément la qualité des couches constituant les barrières de perméation. Une interprétation physique du procédé plasma a été proposée, basée sur le réarrangement atomique induit à chaque interface par les ions de faible énergie (< 40 eV). Pour chacune des voies choisies, des très faibles taux de perméation (4 à 7 × 10-5 g/m2.jour) ont été atteints. Avec la combinaison de ces deux méthodes d'encapsulation, nous avons atteint une valeur de WVTR extrêmement faible (6 × 10-6 g/m2.jour), ce qui semble suffisant pour l'utilisation dans des dispositifs organiques
Doping effect on the opto-electrical properties of printed graphene transparent conductive films
No full textSubimal Mishra is an independent sailor on the anti-establishment path: In thought and language (Based on selected novelets)/ প্রতিষ্ঠান বিরোধিতার পথে স্বতন্ত্র নাবিক সুবিমল মিশ্র : ভাবে ও ভাষায় (নির্বাচিত নভেলেট অবলম্বনে)
No full textSubimal Mishra (June 20, 1943-February 8, 2023) whose name comes first in the list of anti-establishment literary practices. He was proficient in everything from literature, science, philosophy, mythology to history, his ability to coordinate in his writing is proof of this. Subimal Mishra wrote a critique of his own writing. His favorite author was Kamalkumar Mazumder. He was directly influenced by the aggressive language of Kamalkumar Majumder. According to him, the one who can attack the language keeps the language alive. His last advice was \u27don\u27t surrender\u27. He never surrendered himself. From the beginning to the end of his literary career, he wrote only in Little Magazine. Despite repeated invitations, he did not work with any established magazine or publishing house. He did not bow down to any powerful institution. Therefore, in the era of advertising, he did not get much recognition among the readers. He himself was the author, publisher, printer, shipper and bookseller of his books. He has done at least five-six papers in his whole life. Despite his immense love and devotion, he could not save a single one. Subimal Mishra\u27s seventh and last magazine was his own—\u27Patalgaddi\u27, each issue of which was the last issue. The ‘Pathak Samabaya\u27 was developed completely experimentally. He called his writings non-stories, anti-stories or anti-novels in the case of novels. His main point is that a piece of writing is not just a text, nor is a book just a reading object—it is a whole art. The main themes of his writings are sexuality and politics. His protest against sexual violence. Therefore, even in the protest, the terrible image of sexual violence has emerged. Some say he composed pornography. His writing is unreadable due to the use of vulgar words. If you want to understand Subimal Mishra, you have to leave the conservative mentality. As a special approach, the author has chosen a satirical ironic language. Several other important themes can be noted in his writings— scientific consciousness, love of nature, sense of duty of a conscious citizen, foresight about world politics etc. On the whole, his thinking, use of language and style of presentation have made him a star in Bengali literature. In this article, the uniqueness of his writing is realized by reviewing his two novelets or novela \u27Tejashkriya Abarjona\u27 (1980) and \u27Adyanta Manush\u27 (1992)
Study on Graphene Based Next Generation Flexible Photodetector for Optical Communication
No full textScalable inkjet printing of shear-exfoliated graphene transparent conductive films
No full textIn this study, we demonstrate scalable and efficient inkjet printing of graphene flexible transparent conducting films (TCFs). The highly concentrated and stable graphene ink (3.2 mg/mL) that is dominated by 4-layer graphene flakes is achieved by means of shear exfoliation process. The printed graphene TCFs with DC conductivity of ∼4 × 104 S/m (sheet resistance 260 Ω/□ coupled with optical transparency of 86%) without intentional doping are readily obtained. Excellent flexibility and air stability of the printed graphene TCFs allow their potential applications in different flexible opto-electronics devices. Systematic investigation of the inkjet printing of graphene and the annealing effect on the graphene TCFs is presented.</p
Interface effects on the moisture barrier properties of SiN x /PMMA/SiN x hybrid structure
No full textInternational audienceEasily degradable organic photovoltaic (OPV) devices based on flexible polymer substrates require barrier films exhibiting extremely low permeation rates for water vapor. We report the barrier properties of hard/ soft alternating layer structures where a soft PMMA layer is sandwiched between two hard SiN x layers. The interfaces between the hard/soft layers hinder the propagation of pinholes from one single-layer to the other and thus have an effect on the overall barrier properties of the whole system. We focus our attention on the effect of increasing number of interfaces on the final barrier properties. The encapsulation barrier properties of these layers are assessed using the electrical calcium test. A minimum water vapor transmission rate (WVTR) of ~ 2 × 10 −4 g/m 2 ·day is reported for 7 hard/soft interfaces, which has also high potential for flexible barrier applications
