Ofet

Electro-conductive textiles are mostly fabrics that have conductive elements or electronics integrated into them to achieve electrical characteristics. They have acquired considerable attention in applications involving sensors, communications, heating textiles, entertainment, health care, safety etc. To produce electro-conductive textiles, several techniques, e.g. chemical treating with conductive polymers on various textile materials, or using different technologies, e.g. knitting, weaving, embroidery techniques to include conductive threads into fabric interconnections etc., are being used. Electro-conductive fabrics are flexible enough to be adapted to quick changes in any particular application, beginning with wearable purposes and sensing needs as specified by many different groups. The ability of electro-conductive textiles to conduct electricity is the most essential property they must possess. In addition, the applications that may be worn should have stable electrical, the...

Microfluidics integration of acoustic biosensors is an actively developing field. Despite significant progress in “passive” microfluidic technology, integration with microacoustic devices is still in its research state. The major challenge is bonding polymers with monocrystalline piezoelectrics to seal microfluidic biosensors. In this contribution, we specifically address the challenge of microfluidics integration on gallium arsenide (GaAs) acoustic biosensors. We have developed a robust plasma-assisted bonding technology, allowing strong connections between PDMS microfluidic chip and GaAs/SiO2 at low temperatures (70 °C). Mechanical and fluidic performances of fabricated device were studied. The bonding surfaces were characterized by water contact angle measurement and ATR-FTIR, AFM, and SEM analysis. The bonding strength was characterized using a tensile machine and pressure/leakage tests. The study showed that the sealed chips were able to achieve a limit of high bonding strength...

Cette these porte sur l'etude d'un dielectrique de type ferroelectrique pour une application aux transistors organiques. La configuration adoptee est de type bottom-gate top- contact. Le materiau semi-conducteur utilise est un transporteur d'electrons. Dans la premiere partie de ce projet, nous avons realise des transistors organiques a effet de champ (OFETs) avec une couche de PMMA comme dielectrique de grille. Ce materiau, tres etudie et connu, permet d'avoir un composant servant de reference. Nous avons egalement mene une etude sur la longueur de canal, la vitesse de depot du semi-conducteur organique et l'epaisseur du dielectrique, en vue d'en deduire l'influence de ces grandeurs sur les performances electriques des OFETs. Apres l'optimisation de ces parametres, nous avons demontre une amelioration de la mobilite des porteurs, une augmentation du rapport Ion/Ioff, une amelioration de la capacite et une diminution des tensions d'alimentation et...

We report on the reduction of contact resistance in solution-processed TIPS-pentacene (6,13-bis(triisopropylsilylethynyl)pentacene) and PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) top-gate bottom-contact organic field-effect transistors (OFETs) by using different contact-modification strategies. The study compares the contact resistance values in devices that comprise Au source/drain electrodes either treated with 2,3,4,5,6-pentafluorothiophenol (PFBT), or modified with an evaporated thin layer of the metal-organic molecular dopant molybdenum tris-[1,2-bis(trifluoromethyl)ethane-1,2-dithiolene] (Mo(tfd)3), or modified with a thin layer of the oxide MoO3. An improved performance is observed in devices modified with Mo(tfd)3 or MoO3 as compared to devices in which Au electrodes are modified with PFBT. We discuss the origin of the decrease in contact resistance in terms of increase of the work function of the modified Au electrodes, Fermi-level pinning effects, and decrease ...

Three cyclopentadithiophene-difluorophenylene copolymers (named PhF2,3, PhF2,5, and PhF2,6), which differ by the arrangement of fluorines on the phenylene structural unit, were designed and synthesized for the fabrication of organic field-effect transistors (OFETs). Single crystal structures of model compounds representative of the backbone and density functional theory (DFT) were used to estimate the backbone shape for each copolymer. The different substitution arrangements impact the backbone secondary structure through different nonbonding F···H interactions. PhF2,5 and PhF2,6 assumed more linear backbones relative to PhF2,3, which in turn impacts self-assembly and polymer chain alignment on nanogrooved (NG) substrates. A larger improvement of charge carrier mobility for the more linear backbones was achieved when using NG substrates. Among the three polymers, PhF2,6 achieved the highest average field-effect hole mobility (5.1 cmVs). As evidenced by grazing incidence wide-angle X...

We demonstrate high-performance and stable organic field-effect transistors (OFETs) using parylene-based double-layer gate dielectrics (DLGDs). DLGDs, consisting of parylene C as the upper layer and F as the lower layer, are designed to simultaneously provide good interface and bulk gate dielectric properties by exploiting the advantages of each gate dielectric. The structural effects of DLGDs are systematically investigated by evaluating the electrical characteristics and dielectric properties while varying the thickness ratio of each gate dielectric. The OFET with the optimized DLGD exhibits high performance and operational stability. This systematic approach will be useful for realizing practical electronic applications.

The p-type semiconducting properties of a triphenylene-fused triindole mesogen, have been studied by applying two complementary methods which have different alignment requirements. The attachment of only three flexible alkyl chains to the nitrogen atoms of this π-extended core is sufficient to induce columnar mesomorphism. High hole mobility values (0.65 cm(2) V(-1) s(-1)) have been estimated by space-charge limited current (SCLC) measurements in a diode-like structure which are easily prepared from the melt, rendering this material a good candidate for OPVs and OLEDs devices. The mobility predicted theoretically via a hole-hopping mechanism is in very good agreement with the experimental values determined at the SCLC regime. On the other hand the hole mobility determined on solution processed thin film transistors (OFETs) is significantly lower, which can be rationalized by the high tendency of these large molecules to align on surfaces with their extended π-conjugated core paralle...

Solution-processed n-type organic field-effect transistors (OFETs) are essential elements for developing large-area, low-cost, and all organic logic/complementary circuits. Nonetheless, the development of air-stable n-type organic semiconductors (OSCs) lags behind their p-type counterparts. The trapping of electrons at the semiconductor-dielectric interface leads to a lower performance and operational stability. Herein, we report printed small-molecule n-type OFETs based on a blend with a binder polymer, which enhances the device stability due to the improvement of the semiconductor-dielectric interface quality and a self-encapsulation. Both combined effects prevent the fast deterioration of the OSC. Additionally, a complementary metal-oxide semiconductor-like inverter is fabricated depositing p-type and n-type OSCs simultaneously.

Organic field-effect transistorsd are the most fundamental device unit in organic electronics. Interface engineering on the semiconductor/dielectric interface is an effective approach for improving device performance, particularly for enhancing charge transport at conducting channels. Here, we report flat-lying molecular monolayers that exhibit good uniformity and high crystallinity at the semiconductor/dielectric interface deposited through slow thermal evaporation. Transistor devices achieve high carrier mobility of up to 2.80 cm2 V-1 s-1, which indicates a remarkably improved device performance compared with devices that are completely based on fast-evaporated films. Interfacial flat-lying monolayers benefit charge transport by suppressing the polarization of dipoles and narrowing the widening of trap density of states. Therefore, our work provides a promising strategy for enhancing the performance of OFETs by using interfacial flat-lying molecular monolayers.