1,721,020 research outputs found
Sintesi e nanostrutturazione di film di PEDOT sottil e conduttivi mediante polimerizzazione in fase liquida
Full text linkI polimeri conduttivi (CPs) rappresentano una valida alternativa alle tecnologie silicon-based nella produzione di dispositivi elettronici organici. Tra questi, il PEDOT ne è un esempio notevole grazie alle sue eccellenti proprietà elettriche, alla trasparenza e alla stabilità. Questo progetto si è concentrato sulla sintesi di film di PEDOT mediante polimerizzazione in fase liquida depositando sequenzialmente soluzioni di ossidante (V2O5) e monomero (EDOT) su substrati di vetro. Variabili come il tempo di deposizione dell'ossidante, la concentrazione e la velocità di rotazione sono state regolate per migliorare le proprietà del film. La conduttività è stata misurata con il metodo Van der Pauw. Inoltre, la nanostrutturazione precisa di film di PEDOT è stata ottenuta mediante “nanosphere lithography
Sintesi e nanostrutturazione di film sottili e conduttivi di PEDOT mediante polimerizzazione in fase liquida
No full textI polimeri conduttivi (CPs) rappresentano una valida alternativa alle tecnologie silicon-based nella produzione di dispositivi elettronici organici. Tra questi, il PEDOT ne è un esempio notevole grazie alle sue eccellenti proprietà elettriche, alla trasparenza e alla stabilità. Questo progetto si è concentrato sulla sintesi di film di PEDOT mediante polimerizzazione in fase liquida depositando sequenzialmente soluzioni di ossidante (V2O5) e monomero (EDOT) su substrati di vetro. Variabili come il tempo di deposizione dell'ossidante, la concentrazione e la velocità di rotazione sono state regolate per migliorare le proprietà del film. La conduttività è stata misurata con il metodo Van der Pauw. Inoltre, la nanostrutturazione precisa di film di PEDOT è stata ottenuta mediante “nanosphere lithography
Synthesis and nanostructuration of thin and conductive PEDOT films by liquid-phase polymerization
Full text linkConductive polymers (CPs) have represented a key research topic in the field of organic electronic devices, as alternatives to silicon-based technologies. Among them, poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most used and investigated materials because of its good and tailorable electrical properties, transparency to visible light and environmental stability. For all these reasons, PEDOT has found applications in organic solar cells, supercapacitors, organic light-emitting diodes and nanostructured devices.
In this project, we studied the synthesis of this polymer using a liquid-phase polymerization process.[1]
This process involves the sequential deposition of an oxidant solution (vanadium pentoxide) and a monomer solution (EDOT) onto a glass substrate treated with piranha solution. The resulting film is washed with a solvent to eliminate the excess monomer and then subjected to annealing heat treatment.
To enhance the properties of the polymeric film, we varied the deposition time of the oxidizing solution, the rotation speed and the concentration of the oxidizing solution.
The analysis showed that the thickness of the polymeric film is primarily influenced by the deposition time of the oxidant solution.
Additionally, the concentration of the oxidant slightly affects the polymer thickness due to the varying viscosities of more and less concentrated solutions. We determined the morphology and thickness of the samples using optical profilometry and measured the conductivity of the samples with the Van der Pauw method using a 4-point probe in electrical contact with the polymeric film. A direct current is applied between the outer test leads, while a voltage drop is measured between the inner leads, providing the sheet resistance (Rs, measured in Ω/□).
We studied the nanostructuring process of the films using nanosphere lithography. To improve the deposition of nanospheres on the PEDOT layer, a silica one was applied to the film. This layer facilitated the formation of a monolayer of polystyrene particles, which was subsequently reduced using reactive ion etching (RIE).[2]
The resulting mask enabled the precise nanostructuring of the PEDOT films. By optimizing this process, we achieved PEDOT nanostructures with a high degree of order
Solid-state dewetting of thin Au films studied with real-time, in situ spectroscopic ellipsometry
No full textWe report the design and testing of a small, high vacuum chamber that allows real-time, in situ spectroscopic ellipsometry (SE) measurements; the chamber was designed to be easily inserted within the arms of a commercial ellipsometer. As a test application, we investigated the temperature-induced solid-state dewetting of thin (20 to 8 nm) Au layers on Si wafers. In situ SE measurements acquired in real time during the heating of the samples reveal features that can be related to the birth of a localized surface plasmon resonance (LSPR), and demonstrate the presence of a temperature threshold for the solid-state dewetting
Mg deposition on Ag(100): temperature evolution of the structural and electronic properties
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Correlation of site-selective oxygen adsorption with step-induced magnetic anisotropy in nanopatterned Fe films
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DATA INTENSIVE REVIEW MINING FOR SENTIMENT CLASSIFICATION ACROSS HETEROGENEOUS DOMAINS
No full textThe automatic detection of orientation and
emotions in texts is becoming increasingly important in the Web
2.0 scenario. There is a considerable need for innovative
techniques and tools capable of identifying and detecting the
attitude of unstructured text. The paper tackles two crucial
aspects of the sentiment classification problem: first, the
computational complexity of the deployed framework; second,
the ability of the framework itself to operate effectively in
heterogeneous commercial domains. The proposed approach
adopts empirical learning to implement the sentimentclassification
technology, and uses a distance-based predictive
model to combine computational efficiency and modularity. A
suitably designed semantic-based metric is the cognitive core that
measures the distance between two user reviews, according to the
sentiment they communicate. The framework ultimately nullifies
the training process; at the same time, it takes advantage of a
classification procedure whose computational cost increases
linearly when the training corpus increases. To attain an
objective measurement of the actual accuracy of the sentiment
classification method, a campaign of tests involved a pair of
complex, real-world scoring domains; the goal was to compare
the predicted sentiment scores with actual scores provided by
human assessors. Experimental results confirmed that the overall
approach attained satisfactory performances in terms of both
cross-domain classification accuracy and computational
efficiency
Temperature-dependent permittivity of silver and implications for thermoplasmonics
No full textSilver is an extremely appealing metal for plasmonics due to its very low optical losses in the visible and near-ultraviolet range and its relatively low reactivity. Within the emerging field of thermoplasmonics, where light-metal interactions are exploited to generate heat on the nanometric scale, knowledge of temperature-dependent complex permittivities of plasmonic materials is indispensable. We extracted the temperature-dependent complex permittivity of silver Ag by spectroscopic ellipsometry under high-vacuum conditions. For rising T, we observed an increase of the free-electron contribution to the imaginary part of the permittivity Im[Ag] and a temperature-dependent absorption band splitting off the interband absorption edge in the 320-360-nm range. Around 340 nm the relative increase of Im[Ag] at 600 K with respect to its room-temperature value is around 500%. In order to understand the implications of this behavior on silver thermoplasmonics, we computed the temperature-dependent extinction efficiency of oblate Ag ellipsoids with localized plasmon resonance within the 320-360-nm range. We predict that dramatic damping of the plasmon resonance occurs for increasing temperature, possibly leading to intriguing self-limiting effects in Ag thermoplasmonics
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