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Organic Thin-Film Transistors (organic + thin-film_transistor)

Distribution by Scientific Domains

Polymers and Materials Science	95%

Selected Abstracts

Ultrathin, Organic, Semiconductor/Polymer Blends by Scanning Corona-Discharge Coating for High-Performance Organic Thin-Film Transistors

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
Hee Joon Jung
Abstract A new thin-film coating process, scanning corona-discharge coating (SCDC), to fabricate ultrathin tri-isopropylsilylethynyl pentacene (TIPS-PEN)/amorphous-polymer blend layers suitable for high-performance, bottom-gate, organic thin-film transistors (OTFTs) is described. The method is based on utilizing the electrodynamic flow of gas molecules that are corona-discharged at a sharp metallic tip under a high voltage and subsequently directed towards a bottom electrode. With the static movement of the bottom electrode, on which a blend solution of TIPS-PEN and an amorphous polymer is deposited, SCDC provides an efficient route to produce uniform blend films with thicknesses of less than one hundred nanometers, in which the TIPS-PEN and the amorphous polymer are vertically phase-separated into a bilayered structure with a single-crystalline nature of the TIPS-PEN. A bottom-gate field-effect transistor with a blend layer of TIPS-PEN/polystyrene (PS) (90/10 wt%) operated at ambient conditions, for example, indeed exhibits a highly reliable device performance with a field-effect mobility of approximately 0.23 cm2 V,1 s,1: two orders of magnitude greater than that of a spin-coated blend film. SCDC also turns out to be applicable to other amorphous polymers, such as poly(, -methyl styrene) and poly(methyl methacrylate) and, readily combined with the conventional transfer-printing technique, gives rise to micropatterned arrays of TIPS-PEN/polymer films. [source]

Solubility-Induced Ordered Polythiophene Precursors for High-Performance Organic Thin-Film Transistors

ADVANCED FUNCTIONAL MATERIALS, Issue 8 2009
Yeong Don Park
Abstract With the aim of enhancing the field-effect mobility of self-assembled regioregular poly(3-hexylthiophene), P3HT, by promoting two-dimensional molecular ordering, the organization of the P3HT in precursor solutions is transformed from random-coil conformation to ordered aggregates by adding small amounts of the non-solvent acetonitrile to the solutions prior to film formation. The ordering of the precursor in the solutions significantly increases the crystallinity of the P3HT thin films. It is found that with the appropriate acetonitrile concentration in the precursor solution, the resulting P3HT nanocrystals adopt a highly ordered molecular structure with a field-effect mobility dramatically improved by a factor of approximately 20 depending on the P3HT concentration. This improvement is due to the change in the P3HT organization in the precursor solution from random-coil conformation to an ordered aggregate structure as a result of the addition of acetonitrile. In the good solvent chloroform, the P3HT molecules are molecularly dissolved and adopt a random-coil conformation, whereas upon the addition of acetonitrile, which is a non-solvent for aromatic backbones and alkyl side chains, 1D or 2D aggregation of the P3HT molecules occurs depending on the P3HT concentration. This state minimizes the unfavorable interactions between the poorly soluble P3HT and the acetonitrile solvent, and maximizes the favorable ,,, stacking interactions in the precursor solution, which improves the molecular ordering of the resulting P3HT thin film and enhances the field-effect mobility without post-treatment. [source]

Recent Progress in n-Channel Organic Thin-Film Transistors

ADVANCED MATERIALS, Issue 12 2010
Yugeng Wen
Abstract Particular attention has been focused on n-channel organic thin-film transistors (OTFTs) during the last few years, and the potentially cost-effective circuitry-based applications in flexible electronics, such as flexible radiofrequency identity tags, smart labels, and simple displays, will benefit from this fast development. This article reviews recent progress in performance and molecular design of n-channel semiconductors in the past five years, and limitations and practicable solutions for n-channel OTFTs are dealt with from the viewpoint of OTFT constitution and geometry, molecular design, and thin-film growth conditions. Strategy methodology is especially highlighted with an aim to investigate basic issues in this field. [source]

Organic Thin-Film Transistors Fabricated on Resorbable Biomaterial Substrates

ADVANCED MATERIALS, Issue 5 2010
Christopher J. Bettinger
Organic electronics and biodegradable materials have the potential to be integrated to create a new class of electronic devices for the use in biomedical and environmental applications. Organic thin-film field-effect transistors fabricated using a biodegradable material platform exhibit water stable performance and degrade in vitro. [source]

Organic Thin-Film Transistors: Controlling Nucleation and Crystallization in Solution-Processed Organic Semiconductors for Thin-Film Transistors (Adv. Mater.

ADVANCED MATERIALS, Issue 35 2009
35/2009)
The grain size in solution-processed organic semiconductor thin films for TFTs can be tuned over a range of three orders of magnitude, report Yueh-Lin Loo and co-workers on p. 3605. The process involves the addition of fractional quantities of "impurities" that are capable of seeding the crystallization of the organic semiconductor, and the control thus exerted permitted studies that correlated increasing device mobility with increasing grain size. [source]

A New Poly(thienylenevinylene) Derivative with High Mobility and Oxidative Stability for Organic Thin-Film Transistors and Solar Cells

ADVANCED MATERIALS, Issue 27 2009
Bogyu Lim
A novel thiophene-thienylenevinylene copolymer is synthesized and evaluated for use in organic field-effect transistors and organic solar cells. PETV12T shows good solution processability and high structural organization after annealing. Organic thin-film transistors based on the polymer exhibit high mobility and a high resistance to oxidation. In addition, PETV12T shows potential as an electron donor in bulk heterojunction solar cells. [source]

Utilizing Highly Crystalline Pyroelectric Material as Functional Gate Dielectric in Organic Thin-Film Transistors

ADVANCED MATERIALS, Issue 8 2009
Nguyen Thanh Tien
Highly crystalline P(VDF-TrFE) materials have a large remnant polarization that causes the ID,VD curves to have no current saturation in the region where they normally would. This high crystallinity also results in a positive pyroelectricity, which is different from the conventional low response and nonlinear negative pyroelectricity. [source]

Versatile Use of Vertical-Phase-Separation-Induced Bilayer Structures in Organic Thin-Film Transistors,

ADVANCED MATERIALS, Issue 6 2008
Longzhen Qiu
A semiconductor-top and dielectric-bottom bilayer structure is fabricated by surface-induced vertical phase separation of poly(3-hexylthiophene) (P3HT) and poly(methyl methacrylate) (PMMA) blends (see figure). This structure allows to prepare high-performance, low-semiconductor-content, and low-voltage-driven TFTs in a very effective method, in which the dielectric and semiconductor layers are deposited onto a substrate in a one-step process. [source]

Functionalized Arylacetylene Oligomers for Organic Thin-Film Transistors (OTFTs),

ADVANCED MATERIALS, Issue 10 2005

Oligo(arylacetylene)-based organic thin-film transistors (OTFTs) possess good structural order and smooth film morphologies, and exhibit field-effect mobilities of 0.3,cm2,V,1,s,1, one of the highest field-effect mobilities reported for an OTFT device that does not possess a self-assembled-layer configuration. The Figure shows the measured output characteristics (drain,source current, IDS versus drain,source voltage, VDS) at different gate voltages (VG). [source]

Self-Organized Organic Thin-Film Transistors on Plastic,

ADVANCED MATERIALS, Issue 8 2004
Y. Choi
The development of the self-organized growth of pentacence thin films on the channel region of a thin-film transistor (TFT) using surface modifications induced by organic vapor phase deposition is reported (see Figure). A bottom-contact TFT on plastic using an organic gate insulator of cross-linked poly-(4-vinylphenol) exhibited a field-effect mobility of 1.2 cm2/Vs and an on/off current ratio of ,,107. [source]

New Soluble Pentacene Precursors for the Application of Organic Thin-Film Transistors.

CHEMINFORM, Issue 16 2004
Kyung Soo Suh
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Organic Thin-film Transistors Based on Polythiophene Nanowires Embedded in Insulating Polymer

ADVANCED MATERIALS, Issue 13 2009
Longzhen Qiu
Blending poly(3-hexylthiophene) (P3HT) and amorphous polystyrene (PS) using a marginal solvent (CH2Cl2) with temperature-dependent solubility allows a reduction of the semiconductor content to as low as 3 wt% without considerable degradation of the field-effect electronic properties. Morphological and structural studies reveal that the P3HT molecules in these blends form highly crystalline, interconnected nanofibrillar networks. [source]

A New Poly(thienylenevinylene) Derivative with High Mobility and Oxidative Stability for Organic Thin-Film Transistors and Solar Cells

Air-Operable, High-Mobility Organic Transistors with Semifluorinated Side Chains and Unsubstituted Naphthalenetetracarboxylic Diimide Cores: High Mobility and Environmental and Bias Stress Stability from the Perfluorooctylpropyl Side Chain

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
Byung Jun Jung
Abstract N,N,-bis(3-(perfluoroctyl)propyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide (8,3-NTCDI) was newly synthesized, as were related fluorooctylalkyl-NTCDIs and alkyl-NTCDIs. The 8,3-NTCDI-based organic thin-film transistor (OTFT) on an octadecyltrimethoxysilane (OTS)-treated Si/SiO2 substrate shows apparent electron mobility approaching 0.7 cm2 V -1s -1 in air. The fluorooctylethyl-NTCDI (8,2-NTCDI) and fluorooctylbutyl-NTCDI (8,4-NTCDI) had significantly inferior properties even though their chemical structures are only slightly different, and nonfluorinated decyl and undecyl NTCDIs did not operate predictably in air. From atomic force microscopy, the 8,3-NTCDI active layer deposited with the substrate at 120 °C forms a polycrystalline film with grain sizes >4,m. Mobilities were stable in air for one week. After 100 days in air, the average mobility of three OTFTs decreased from 0.62 to 0.12 cm2 V -1s -1, but stabilized thereafter. The threshold voltage (VT) increased by 15 V in air, but only by 3 V under nitrogen, after one week. On/off ratios were stable in air throughout. We also investigated transistor stability to gate bias stress. The transistor on hexamethlydisilazane (HMDS) is more stable than that on OTS with mobility comparable to amorphous Si TFTs. VT shifts caused by ON (30 V) and OFF (,20 V) gate bias stress for the HMDS samples for 1 hour were 1.79 V and 1.27 V under N2, respectively, and relaxation times of 106 and 107 s were obtained using the stretched exponential model. These performances are promising for use in transparent display backplanes. [source]

Non-volatile Ferroelectric Poly(vinylidene fluoride- co -trifluoroethylene) Memory Based on a Single-Crystalline Tri-isopropylsilylethynyl Pentacene Field-Effect Transistor

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2009
Seok Ju Kang
Abstract A new type of nonvolatile ferroelectric poly(vinylidene fluoride- co -trifluoroethylene) (P(VDF-TrFE)) memory based on an organic thin-film transistor (OTFT) with a single crystal of tri-isopropylsilylethynyl pentacene (TIPS-PEN) as the active layer is developed. A bottom-gate OTFT is fabricated with a thin P(VDF-TrFE) film gate insulator on which a one-dimensional ribbon-type TIPS-PEN single crystal, grown via a solvent-exchange method, is positioned between the Au source and drain electrodes. Post-thermal treatment optimizes the interface between the flat, single-crystalline ab plane of TIPS-PEN and the polycrystalline P(VDF-TrFE) surface with characteristic needle-like crystalline lamellae. As a consequence, the memory device exhibits a substantially stable source,drain current modulation with an ON/OFF ratio hysteresis greater than 103, which is superior to a ferroelectric P(VDF-TrFE) OTFT that has a vacuum-evaporated pentacene layer. Data retention longer than 5,×,104 s is additionally achieved in ambient conditions by incorporating an interlayer between the gate electrode and P(VDF-TrFE) thin film. The device is environmentally stable for more than 40 days without additional passivation. The deposition of a seed solution of TIPS-PEN on the chemically micropatterned surface allows fabrication arrays of TIPS-PEN single crystals that can be potentially useful for integrated arrays of ferroelectric polymeric TFT memory. [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]

Gate Dielectric Microstructural Control of Pentacene Film Growth Mode and Field-Effect Transistor Performance,

ADVANCED MATERIALS, Issue 18 2007
C. Kim
Organic semiconductor/dielectric interfacial characteristics play a critical role in influencing organic thin-film transistor (OTFT) performance characteristics (see figure). Clear correlations between pentacene film deposition temperature, estimated polymer dielectric surface microstructural mobility, and the corresponding film growth mode, semiconductor phase composition, and carrier mobilities are established. [source]

Ultrathin, Organic, Semiconductor/Polymer Blends by Scanning Corona-Discharge Coating for High-Performance Organic Thin-Film Transistors

High-Performance Air-Stable n-Type Organic Transistors Based on Core-Chlorinated Naphthalene Tetracarboxylic Diimides

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2010
Joon Hak Oh
Abstract Core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are synthesized and employed for n-channel organic thin-film transistors (OTFTs). Structural analyses of the single crystals and thin films are performed and their charge-transport behavior is investigated in terms of structure,property relationships. NDIs with two chlorine substituents are shown to exhibit a herringbone structure with a very close ,-plane distance (3.3,3.4,Å), a large ,-stack overlap (slipping angle ca. 62°), and high crystal densities (2.046,2.091,g,cm,3). These features result in excellent field-effect mobilities of up to 1.43,cm2,V,1,s,1 with minimal hysteresis and high on,off ratios (ca. 107) in air. This is similar to the highest n-channel mobilities in air reported so far. Despite the repulsive interactions of bulky Cl substituents, tetrachlorinated NDIs adopt a slip-stacked face-to-face packing with an interplanar distance of around 3.4,Å, resulting in a high mobility (up to 0.44,cm2,V,1,s,1). The air-stability of dichlorinated NDIs is superior to that of tetrachlorinated NDIs, despite of their higher LUMO levels. This is closely related to the denser packing of the fluorocarbon chains of dichlorinated NDIs, which serves as a kinetic barrier to the diffusion of ambient oxidants. Interestingly, these NDIs show an optimal performance either on bare SiO2 or on octadecyltrimethoxysilane (OTS)-treated SiO2, depending on the carbon number of the fluoroalkyl chains. Their synthetic simplicity and processing versatility combined with their high performance make these semiconductors highly promising for practical applications in flexible electronics. [source]

Threshold Voltage Shifts in Organic Thin-Film Transistors Due to Self-Assembled Monolayers at the Dielectric Surface

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Stefan K. Possanner
Abstract Recently, it has been shown by several groups that the electrical characteristics of organic thin-film transistors (OTFTs) can be significantly influenced by depositing self-assembled monolayers (SAMs) at the organic semiconductor/dielectric interface. In this work, the effect of such SAMs on the transfer characteristics and especially on the threshold voltage of OTFTs is investigated by means of two-dimensional drift-diffusion simulations. The impact of the SAM is modeled either by a permanent space charge layer that can result from chemical reactions with the active material, or by a dipole layer representing an array of ordered dipolar molecules. It is demonstrated that, in both model cases, the presence of the SAM significantly changes the transfer characteristics. In particular, it gives rise to a modified, effective gate voltage Veff that results in a rigid shift of the threshold voltage, ,Vth, relative to a SAM-free OTFT. The achievable amount of threshold voltage shift, however, strongly depends on the actual role of the SAM. While for the investigated device dimensions, an organic SAM acting as a dipole layer can realistically shift the threshold voltage only by a few volts, the changes in the threshold voltage can be more than an order of magnitude larger when the SAM leads to charges at the interface. Based on the analysis of the different cases, a route to experimentally discriminate between SAM-induced space charges and interface dipoles is proposed. The developed model allows for qualitative description of the behavior of organic transistors containing reactive interfacial layers; when incorporating rechargeable carrier trap states and a carrier density-dependent mobility, even a quantitative agreement between theory and recent experiments can be achieved. [source]

Recent Progress in n-Channel Organic Thin-Film Transistors

Inkjet Printing,Process and Its Applications

ADVANCED MATERIALS, Issue 6 2010
Madhusudan Singh
Abstract In this Progress Report we provide an update on recent developments in inkjet printing technology and its applications, which include organic thin-film transistors, light-emitting diodes, solar cells, conductive structures, memory devices, sensors, and biological/pharmaceutical tasks. Various classes of materials and device types are in turn examined and an opinion is offered about the nature of the progress that has been achieved. [source]

Flexible Fullerene Field-Effect Transistors Fabricated Through Solution Processing

ADVANCED MATERIALS, Issue 47 2009
Chao-Feng Sung
C60-based thin-film transistors are fabricated through solution processing. On rigid indium tin oxide glass, the transistors display electron mobilities as high as 0.21,cm2 V,1 s,1 and a threshold voltage of 0.7,V, only slightly lower than those of organic thin-film transistors prepared through vacuum deposition. On ITO-coated PET substrates, the mobilities in the flexible devices (see image) are approximately one order of magnitude lower than those of devices prepared on rigid glass substrates. [source]