EL MARMON EN TAFIRA [Material gráfico]

ÁLBUM FAMILIAR CASA DE COLÓNCopia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

Organic Thin Film Transistors Based on Distyryl-Oligothiophenes: Role of AFM Images in Analyses of Charge Transport Properties

Significant advances have been made recently in the area of organic electronics and optoelectronics based on small molecules as a result of an improved chemistry and a better technology. Together with light emitting diodes and solar cells, transistors are among the most studied components. The development of new semiconductors induced a real improvement in organic thin film transistor’s performances. Additionally, the synthesis of new soluble and air-stable molecules with the ability to process the active materials at low temperatures over large areas on substrates such as plastic or paper provide unique technologies and generate new applications. However the control of the solid state structure has emerged as essential to realize the full intrinsic potential that organic semiconductors possess. Atomic force microscopy (AFM) was likely to contribute to a further advancement of knowledge. The ability of the AFM to produce three dimensional maps at the micro- and nanometer scale has greatly increased its popularity as an imaging tool. Recently, distyryl-oligothiophenes and their derivatives appear as a new class of molecular semiconductors. Detailed morphological studies of organic active layers based on such new semiconductors involved in organic thin film transistors (OTFTs) have brought a large knowledge about the impact of chemical and physico-chemical aspects on charge transport efficiency

Organic transistors and phototransistors based on small molecules

International audienceSignificant advances have been made recently in the area of organic electronics and optoelectronics based on small molecules as a result of the synthesis of new soluble and air-stable molecules. First reported 20 years ago, organic transistors quickly became a focus of intense research and development in academic and industrial laboratories. The great progress achieved thus far offers an opportunity for the production of new small electro-active molecules and the implementation of low-cost device fabrication technologies. This review focuses on recently synthesized p- or n-type organic semiconductors, particularly those suitable for fabrication of solution-processed and/or air-stable field effect transistors with an emphasis on low-cost wet processes. The numerous recent efforts realized in optoelectronics, particularly on phototransistors based on small molecules, offer various opportunities in applications for such organic compounds. Copyright © 2011 Society of Chemical Industr

Aluminum-doped Zinc Oxide Nanocrystals for NO2 Detection at Low Temperature

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Theoretical insight on PTB7:PC 71 BM, PTB7-th:PC 71 BM and Si-PCPDTBT:PC 71 BM interactions governing blend nanoscale morphology for efficient solar cells

International audienceThe nanoscale morphology of solution processed bulk heterojunctions is governed by miscibility of donor and acceptor in the selected solvent and drying of the layer during processing. Ternary blends are of great interest for high efficiency polymer solar cells, but prediction of their morphology is highly complex. Here we perform atomistic simulations to study the miscibility of three different polymers of interest for ternary organic photovoltaics (the small band gap polymers PTB7 and PTB7-th, and the sensitizer Si-PCPDTBT) with the fullerene acceptor PC 71 BM.The free energy of mixing of fullerenes with polymers is calculated as a function of the relative concentration. The blend density is also varied to simulate out-of-equilibrium conditions occurring during layer processing. By analyzing the results within the Flory-Huggins theory we find that, for a specific range of fullerene weight ratios and densely packed blends the sensitizer is most likely located in the host polymer phase due to its low miscibility with the fullerene. This configuration is the preferred one for the solar cell in order to deactivate hole traps typically formed in the binary blends and reduce recombination. Notably, we find that these results can be different qualitatively at lower density and out-of-equilibrium blends. This work shows that weight ratios and density can be in principle chosen to select specific morphologies in ternary organic blends

NO2 Gas Sensing at Room Temperature under Ultra- Violet Light of ZnO Nanocrystals

International audienceNitrogen dioxide (NO2) is a major component of the outdoor air pollution. Microsensors are interesting devices to check and to monitor this toxic oxidizing gas. Recent advances in flexible electronics, a complementary technology to the conventional rigid silicon technology, have motivated research efforts. Flexible substrates enable new applications such as wearable sensors, electronics on skin/organs as well as a possible reducing cost during the fabrication process. However, flexible substrates required low working temperature to avoid thermal degradation. This work aims to prove the possibility to use zinc oxide nanocrystals (ZnO NCs) post-annealed at low temperature as a sensitive material to detect NO 2 at low working temperature. Thus, our study has been performed on rigid substrates to check first the sensitive layer behaviour depending on the temperature. Then, to be able to reduce the working temperature, a continuous UltraViolet illumination has been used. We propose a NO 2 detection at room temperature by ZnO NCs deposited on rigid substrates by spin coating from colloidal solutions as sensitive layers for air quality monitoring

Aluminum-doped Zinc Oxide Nanoparticles Sensing Properties Enhanced by Ultraviolet Light

International audienceThe development of room-temperature gas sensors for nitrogen dioxide gases is of great importance for air quality monitoring due to unhealthy impact on human life and environment. In this work, we focus on Aluminum-doped Zinc Oxide sensing properties. We compare nitrogen dioxide detection at room temperature in dark and under ultraviolet or blue illuminations. Working temperature from 25°C up to 100°C have been also performed in dark and under UV and blue Light Emitted Diodes. Aluminum-doped Zinc Oxide nanoparticles have been deposited by drop coating from colloidal solution as sensitive layer for air quality monitoring on Si/SiO2 substrate. Herein, a brief description of the process steps will be provided. We demonstrate that UV light and temperature enhance gas-sensing properties with good reversibility and repeatability

Synthesis and thin film electronic properties of two pyrene-substituted oligothiophene derivatives

International audienceThe synthesis and the electric properties of two new pyrene end-substituted oligothiophene derivatives (Py-nT, n = 2,4) are described. The highest hole mobility (ca. 10−3 cm2 V−1 s−1) was obtained for vacuum evaporated thin films of Py-4T as the active layer in field effect transistors based on hexamethyldisilazane-treated SiO2/Si substrates. Moreover, Py-nT thin films were doped with molecular iodine, which led to a 106 fold increase of electric conductivity. In the case of Py-4T, a value of 1 S cm−1 was obtained after 21 minutes exposure to iodine vapor

Aluminum-doped Zinc Oxide Nanoparticles Sensing Properties Enhanced by Ultraviolet Light

International audienceThe development of room-temperature gas sensors for nitrogen dioxide gases is of great importance for air quality monitoring due to unhealthy impact on human life and environment. In this work, we focus on Aluminum-doped Zinc Oxide sensing properties. We compare nitrogen dioxide detection at room temperature in dark and under ultraviolet or blue illuminations. Working temperature from 25°C up to 100°C have been also performed in dark and under UV and blue Light Emitted Diodes. Aluminum-doped Zinc Oxide nanoparticles have been deposited by drop coating from colloidal solution as sensitive layer for air quality monitoring on Si/SiO2 substrate. Herein, a brief description of the process steps will be provided. We demonstrate that UV light and temperature enhance gas-sensing properties with good reversibility and repeatability