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Electrical Performance (electrical + performance)
Selected AbstractsOrganic Field-Effect Transistors: Planarization of Polymeric Field-Effect Transistors: Improvement of Nanomorphology and Enhancement of Electrical Performance (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Mater. Contact geometry plays an important role in charge injection and transport in organic field-effect transistors. On page 2216, T. Kowalewski, L. M. Porter, et al. show a dramatic effect of electrode planarization on the polymer morphology at the contact edges and a resulting increase in fi eld-effect mobility in short channel length devices, and a corresponding decrease in contact resistance. The cover image shows atomic force micrograph of individual polymer nanofi brils spanning the length of a 10 µm channel transistor with planarized contacts. [source] Planarization of Polymeric Field-Effect Transistors: Improvement of Nanomorphology and Enhancement of Electrical PerformanceADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Kumar A. Singh Abstract The planarization of bottom-contact organic field-effect transistors (OFETs) resulting in dramatic improvement in the nanomorphology and an associated enhancement in charge injection and transport is reported. Planar OFETs based on regioregular poly(3-hexylthiophene) (rr-P3HT) are fabricated wherein the Au bottom-contacts are recessed completely in the gate-dielectric. Normal OFETs having a conventional bottom-contact configuration with 50-nm-high contacts are used for comparison purpose. A modified solvent-assisted drop-casting process is utilized to form extremely thin rr-P3HT films. This process is critical for direct visualization of the effect of planarization on the polymer morphology. Atomic force micrographs (AFM) show that in a normal OFET the step between the surface of the contacts and the gate dielectric disrupts the self-assembly of the rr-P3HT film, resulting in poor morphology at the contact edges. The planarization of contacts results in notable improvement of the nanomorphology of rr-P3HT, resulting in lower resistance to charge injection. However, an improvement in field-effect mobility is observed only at short channel lengths. AFM shows the presence of well-ordered nanofibrils extending over short channel lengths. At longer channel lengths the presence of grain boundaries significantly minimizes the effect of improvement in contact geometry as the charge transport becomes channel-limited. [source] Redox Cycling of Ni-Based Solid Oxide Fuel Cell Anodes: A ReviewFUEL CELLS, Issue 3 2007D. Sarantaridis Abstract The published literature relating to damage to SOFCs caused by redox cycling of Ni-based anodes is reviewed. The review covers the kinetics of Ni oxidation and NiO reduction (as single phases and as constituents of composites with yttria-stabilised zirconia, YSZ), the dimensional changes associated with redox cycling and the effect of this on the mechanical integrity and electrical performance of cells and stacks. A critical parameter is the expansion strain that is caused by oxidation. Several studies report that the first complete oxidation of a Ni/YSZ composite causes a linear expansion of the order of 1%, but the actual values vary substantially between different investigations. The oxidation strain is the result of microstructural irreversibility during the redox process and leads to strain accumulation over several redox cycles. This can cause mechanical disruption to an anode, anode support or other cell components attached to the anode. A simplified mechanical model of the stress and damage that are likely to be caused by anode expansion is proposed and applied to anode-supported, electrolyte-supported and inert substrate-supported cell configurations. This allows the maximum oxidation strain to avoid damage in each configuration to be estimated. [source] Magnetic-Field-Induced Phase-Selective Synthesis of Ferrosulfide Microrods by a Hydrothermal Process: Microstructure Control and Magnetic Properties,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2006Z. He Abstract Microrods of the ferrosulfide minerals greigite (Fe3S4) and marcasite (FeS2) are selectively synthesized by an in,situ magnetic-field-assisted hydrothermal route. Each complex microrod is composed of fine building blocks with different shapes. The unique magnetic properties of the microrods and electrical performance of a single microrod are studied. The results demonstrate that the magnetic properties of the ferrosulfide minerals are strongly related to their corresponding microstructures. The value of the low-temperature transition increases as the greigite component in the product decreases. The combination of small-molecule sulfur precursors and an applied magnetic field makes possible the selective synthesis of ferrosulfide minerals with different phases and distinct microstructures, underlining the fact that the magnetic field can be a useful tool as well as an independent parameter for the phase-selective synthesis and self-assembly of inorganic building blocks in solution chemistry. [source] High-Performance Solution-Processable Poly(p -phenylene vinylene)s for Air-Stable Organic Field-Effect TransistorsADVANCED FUNCTIONAL MATERIALS, Issue 5 2005Abstract The influence of the substitution pattern (unsymmetrical or symmetrical), the nature of the side chain (linear or branched), and the processing of several solution processable alkoxy-substituted poly(p -phenylene vinylene)s (PPVs) on the charge-carrier mobility in organic field-effect transistors (OFETs) is investigated. We have found the highest mobilities in a class of symmetrically substituted PPVs with linear alkyl chains (e.g., R1, R2,=,n -C11H23, R3,=,n -C18H37). We have shown that the mobility of these PPVs can be improved significantly up to values of 10,2,cm2,V,1,s,1 by annealing at 110,°C. In addition, these devices display an excellent stability in air and dark conditions. No change in the electrical performance is observed, even after storage for thirty days in humid air. [source] Semiconducting Thienothiophene Copolymers: Design, Synthesis, Morphology, and Performance in Thin-Film Organic TransistorsADVANCED MATERIALS, Issue 10-11 2009Iain McCulloch Abstract Organic semiconductors are emerging as a viable alternative to amorphous silicon in a range of thin-film transistor devices. With the possibility to formulate these p-type materials as inks and subsequently print into patterned devices, organic-based transistors offer significant commercial advantages for manufacture, with initial applications such as low performance displays and simple logic being envisaged. Previous limitations of both air stability and electrical performance are now being overcome with a range of both small molecule and polymer-based solution-processable materials, which achieve charge carrier mobilities in excess of 0.5,cm2 V,1 s,1, a benchmark value for amorphous silicon semiconductors. Polymer semiconductors based on thienothiophene copolymers have achieved amongst the highest charge carrier mobilities in solution-processed transistor devices. In this Progress Report, we evaluate the advances and limitations of this class of polymer in transistor devices. [source] High-Performance Polymer-Small Molecule Blend Organic TransistorsADVANCED MATERIALS, Issue 10-11 2009Richard Hamilton A double-gate device is used to demonstrate that a blended formulation of semiconducting small molecules and a polymer matrix can provide high electrical performance within thin-film field-effect transistors (OTFTs) with charge carrier mobilities of greater than 2,cm2,V,1,s,1, good device-to-device uniformity, and the potential to fabricate devices from routine printing techniques. [source] Tape Casting and Dielectric Properties of Zn2Te3O8 -Based Ceramics with an Ultra-Low Sintering TemperatureINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2009Johanna Honkamo The suitability of dielectric ceramics made of zinc tellurate (Zn2Te3O8) and titanium dioxide (TiO2) with an ultra-low sintering temperature (650°C) for tape casting and thus for the multimodule technique with Al electrodes was investigated. The properties of the tape before and after sintering as well as the amount of organic additives for the casting process and a thermal analysis of the tape up to 1000°C are reported. In addition, electrodes on a multilayer module made on stacked tapes were prepared using Al paste and postfiring, followed by relative permittivity and loss tangent measurements to verify the electrical performance of the whole structure. The dielectric properties of the stacked module without any electrodes were also measured. The results show that the composition is well suited for the tape process but extra care should be taken especially with the proper sintering temperature for optimized electrical performance. [source] Characterization of the electrical performance of different signal via geometriesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2006Sedig S. Agili Abstract Several signal via geometries are analyzed for across and through transmission by varying the drill-hole diameter, ratio of the pad and antipad diameters to drill-hole diameter, and number of ground planes. Time- and frequency-domain results showing impedance-, insertion-, and return-loss trends, which are useful for designing via geometries for high-speed transmission, are obtained. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 315,320, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21336 [source] Smart sunglasses based on electrochromic polymersPOLYMER ENGINEERING & SCIENCE, Issue 11 2008Chao Ma Smart sunglasses based on electrochromic polymers are proposed and developed in this study. This article discusses the design, processing, and the optical and electrical performance of a prototype smart sunglasses based on cathodic electrochromic (EC) polymers, which show several merits compared with traditional materials for sunglasses lens as well as other smart window materials. It is a multilayer design of device. The conjugated polymer, poly[3,3-dimethyl-3,4-dihydro-2H-thieno [3,4-b] [1,4]dioxepine] (PProDOT-Me2), is utilized as the electrochromic working layer. The counter layer of the device is vanadium oxide (V2O5) film, which serves as an ion storage layer. There is also a polymer gel electrolyte acting as the ionic transport layer, sandwiched between the working and counter layers. The characteristics of the prototype device are reported, including transmittance (%T), driving power, response time, open circuit memory, and lifetime. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Procedure for determining the uncertainty of photovoltaic module outdoor electrical performance,PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 2 2001K. Whitfield This paper sets forth an uncertainty estimation procedure for the measurement of photovoltaic (PV) electrical performance using natural sunlight and calibrated secondary reference cells. The actual test irradiance should be restricted to values between 800 and 1000,W/m2 in order to assume that maximum power varies linearly with irradiance. Only the uncertainty of maximum power at standard test conditions (STC), i.e., 1000,W/m2 plane-of-array irradiance and 25°C cell temperature, is developed in its entirety. The basic uncertainty analysis principles developed herein, however, can be applied to any electrical variable of interest (e.g., short-circuit current, open-circuit voltage and fill factor). Although the equations presented appear cumbersome, they are easily implemented into a computer spreadsheet. Examples of uncertainty analyses are also presented herein to make the concepts more concrete. Published in 2001 by John Wiley & Sons, Ltd. [source] Novel ZrInZnO Thin-film Transistor with Excellent StabilityADVANCED MATERIALS, Issue 3 2009Jin-Seong Park Novel ZrInZnO semiconductor materials to resolve transistor instability for active-matrix organic light-emitting diodes are proposed. The ZrInZnO film is preprared using a cosputtering method, and presents a nanocrystal structure embedded in an amorphous matrix. The thin-film transistors fabricated have good electrical performances as well as excellent stability under long-term bias stresses. [source] Polarization curves for an alkaline water electrolysis at a small pin vertical electrode to produce hydrogen,AICHE JOURNAL, Issue 9 2010Ph. Mandin Abstract During two-phase electrolysis for hydrogen production, according with alkaline,water electrolysis process, there are bubbles which are created at electrodes which imply a great hydrodynamic acceleration in the normal earth gravity field and then a quite important electrical properties and electrochemical processes disturbance, for both transport and reaction. This disturbance can lead to the modification of the local current density and to anode effects for example. In this work, a model experimental set-up is studied. The vertical pine electrode of small electro active surface area is surrounded with a large surface counter electrode. The hydrogen production is performed at the working electrode and effort is focused here upon the global electrochemical cell electrical performances. The polarization curves intensity vs. applied voltage are experimentally measured and presented for different factors such as: the electro active species concentration, nature and counter electrode diameter factors. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] A slow-wave structure with Koch fractal slot loopsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2002Jung-Hyo Kim Abstract In this Letter, a Koch slot loop in the ground plane has been utilized to obtain slow-wave characteristics, and its electrical performances are analyzed with the use of the ABCD matrix approach. The validity of this approach has been verified through experimental results, and this technique was then applied to microstrip patch antennas in order to obtain a small antenna size. The cross-sectional areas of this type of antenna are 47% to 65% smaller than those of conventional square patches. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 87,88, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10381 [source] | ||||||||||||||||