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Transistor Applications (transistor + application)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Self-Assembly: Molecular Self-Assembled Monolayers and Multilayers for Organic and Unconventional Inorganic Thin-Film Transistor Applications (Adv. Mater.

ADVANCED MATERIALS, Issue 14-15 2009
15/2009)
A self-assembled monolayer (SAM) of azo stillbazolium sandwiched between two conductive electrodes is shown. The upper and lower electrodes are doped silicon and a Hg drop, respectively, a configuration often used for measuring the conductivity of SAMs and multilayers of hybrid organic and inorganic materials. The evaluation and implementation of these unconventional materials in complex device architectures is highlighted in the review on page 1407 by Sara DiBenedetto et al. [source]

Molecular Self-Assembled Monolayers and Multilayers for Organic and Unconventional Inorganic Thin-Film Transistor Applications

ADVANCED MATERIALS, Issue 14-15 2009
Sara A. DiBenedetto
Abstract Principal goals in organic thin-film transistor (OTFT) gate dielectric research include achieving: (i) low gate leakage currents and good chemical/thermal stability, (ii) minimized interface trap state densities to maximize charge transport efficiency, (iii) compatibility with both p- and n- channel organic semiconductors, (iv) enhanced capacitance to lower OTFT operating voltages, and (v) efficient fabrication via solution-phase processing methods. In this Review, we focus on a prominent class of alternative gate dielectric materials: self-assembled monolayers (SAMs) and multilayers (SAMTs) of organic molecules having good insulating properties and large capacitance values, requisite properties for addressing these challenges. We first describe the formation and properties of SAMs on various surfaces (metals and oxides), followed by a discussion of fundamental factors governing charge transport through SAMs. The last section focuses on the roles that SAMs and SAMTs play in OTFTs, such as surface treatments, gate dielectrics, and finally as the semiconductor layer in ultra-thin OTFTs. [source]

Planar Alignment of Columnar Discotic Liquid Crystals by Isotropic Phase Dewetting on Chemically Patterned Surfaces

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2010
Jonathan P. Bramble
Abstract A novel method of creating planar aligned columnar discotic liquid crystals (cDLCs) on surfaces, which also gives control over the azimuthal angle, is presented. Surfaces are chemically patterned with stripes via microcontact printing of organothiol self-assembled monolayers (SAMs) on gold, or via deep UV patterning of organosilane SAMs on silicon. These are then used to isolate long droplets of cDLCs by dewetting in the isotropic phase. Upon cooling from the isotropic into the hexagonal columnar phase, polarizing microscopy reveals that the cDLC aligns in a planar orientation. Results for three triphenylene derivatives (HAT-6, HHTT, H7T) and for a phthalocyanine derivative (8H2Pc) are presented. H7T and HAT-6 are found to align with the director perpendicular to the stripe direction, but HHTT and 8H2Pc align parallel to the stripe direction. This relatively simple new method for creating planar aligned columnar phases of DLCs gives control over the azimuthal angle: a condition required for organic field-effect transistor applications of cDLCs. [source]

Modeling Electron and Hole Transport in Fluoroarene-Oligothiopene Semiconductors: Investigation of Geometric and Electronic Structure Properties,

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2008
E. Koh
Abstract A theoretical study using density functional theory is undertaken to gain insight into how the structural, electronic, and electron-transfer characteristics of three Fluoroarene-oligothiophene semiconductors influence the preferred transport of electrons versus holes in field-effect transistor applications. The intermolecular electronic coupling interactions are analyzed through both a simplified energy-splitting in dimer (ESID) model and as a function of the entire dimer Hamiltonian in order to understand the impact of site energy differences; our results indicate that these differences are generally negligible for the series and, hence, use of the ESID model is valid. In addition, we also investigate the reduction and oxidation processes to understand the magnitudes of the intramolecular reorganization energy for the charge-hopping process and expected barrier heights for electron and hole injection into these materials. From the electronic coupling and intramolecular reorganization energies, estimates of the nearest-neighbor electron-transfer hopping rate constant for electrons are obtained. The ionization energetics suggest favored electron injection for the system with perfluoroarene groups at the end of the thiophene core, in agreement with experiments. The combined analyses of the electron-transfer properties and ionization processes suggest possible ambipolar behavior for these materials under favorable device conditions. [source]