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Charge-transport Properties (charge-transport + property)
Selected AbstractsOrganic Electronics: Solution-Grown, Macroscopic Organic Single Crystals Exhibiting Three-Dimensional Anisotropic Charge-Transport Properties (Adv. Mater.ADVANCED MATERIALS, Issue 18 200918/2009) Organic single crystals have the potential to delivering novel electronic devices based on three-dimensional anisotropic electronic transport. The cover shows single crystals of 4-hydroxycyanobenzene (4HCB) grown from solution behind a distorted-perspective partial representation of the crystalline structure hinting at their molecular constituents. The carrier mobility, anisotropic along the three crystallographic axes, is discussed by Fraleoni-Morgera, Fraboni, Femoni, and co-workers on p. 1835. Dr. George Kourousias is acknowledged for the cover design and artwork. [source] Solution-Grown, Macroscopic Organic Single Crystals Exhibiting Three-Dimensional Anisotropic Charge-Transport PropertiesADVANCED MATERIALS, Issue 18 2009Beatrice Fraboni Macroscopic single crystals of 4-hydroxy-cyanobenzene (4HCB) grown from solution exhibit reproducible and marked 3D mobility anisotropy. Air-gap OFET measurements along the planar axes a and b deliver average mobilities of 3,×,10,2 and 6,×,10,3,cm2 V,1 s,1, respectively. Space-charge-limited current (SCLC) experiments reveal an average mobility along the c axis of 4,×,10,6,cm2,V,1,s,1. [source] Interface Modification to Improve Hole-Injection Properties in Organic Electronic Devices,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2006A. Choulis Abstract The performance of organic electronic devices is often limited by injection. In this paper, improvement of hole injection in organic electronic devices by conditioning of the interface between the hole-conducting layer (buffer layer) and the active organic semiconductor layer is demonstrated. The conditioning is performed by spin-coating poly(9,9-dioctyl-fluorene- co - N - (4-butylphenyl)-diphenylamine) (TFB) on top of the poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) buffer layer, followed by an organic solvent wash, which results in a TFB residue on the surface of the PEDOT:PSS. Changes in the hole-injection energy barriers, bulk charge-transport properties, and current,voltage characteristics observed in a representative PFO-based (PFO: poly(9,9-dioctylfluorene)) diode suggest that conditioning of PEDOT:PSS surface with TFB creates a stepped electronic profile that dramatically improves the hole-injection properties of organic electronic devices. [source] Efficient, Stable Bulk Charge Transport in Crystalline/Crystalline Semiconductor,Insulator BlendsADVANCED MATERIALS, Issue 44 2009Avinesh Kumar Efficient and stable ambipolar charge transport in the bulk of crystalline/crystalline P3HT/HDPE systems, as evidenced by time-of-flight (TOF) photoconductivity measurements, is found. Interestingly, certain blend compositions displayed significantly enhanced bulk charge-transport properties compared to neat P3HT, with ,TOF measured for 80:20,wt% P3HT:PE blends being up to one order of magnitude higher than those found in neat P3HT. [source] Tuning Crystalline Solid-State Order and Charge Transport via Building-Block Modification of OligothiophenesADVANCED MATERIALS, Issue 36 2009Colin Reese The packing structure of a series of oligothiophenes is tuned via terminal substitution (see figure). The structural changes dramatically alter intermolecular interactions and charge-transport properties, as measured by elastomeric single-crystal field-effect transistors. Electronic structure calculations reveal the sensitivity of the transport efficiency to orbital nodal alignment, as correlated to the observed trend in field-effect mobilities. [source] Precise Structure of Pentacene Monolayers on Amorphous Silicon Oxide and Relation to Charge TransportADVANCED MATERIALS, Issue 22 2009Stefan C. B. Mannsfeld The precise molecular packing in pentacene monolayers on silicon oxide is determined for the first time using a combination of grazing incidence X-ray diffraction (GIXD) and crystallographic refinement calculations. The pentacene molecules are found to adopt a completely tilt-free herringbone motif, the charge-transport properties of which are discussed on the basis of density functional theory calculations. [source] Charge-Transport Anisotropy Due to Grain Boundaries in Directionally Crystallized Thin Films of Regioregular Poly(3-hexylthiophene)ADVANCED MATERIALS, Issue 16 2009Leslie H. Jimison P3HT films that are highly anisotropic in-plane are produced using a directional crystallization technique, and the charge-transport properties of grain bourdaries between different orientations of crystallites are studied. Boundaries along the fiber provide a small barrier to charge transport when compared to fiber-to-fiber grain boundaries. The films allow a correlation to be drawn between the grain-boundary type and charge-transport behavior in P3HT. [source] Magnus' Green Salt Revisited: Impact of Platinum,Platinum Interactions on Electronic Structure and Carrier Mobilities,ADVANCED MATERIALS, Issue 15 2006E.-G. Kim Magnus' green salt is the prototype of a class of organic,inorganic hybrid semiconducting materials that combine attractive charge-transport properties and processability. By using density-functional-theory methods, the electronic structure of Magnus' green salt is investigated, in particular the nature of the interplatinum interactions (see figure). In conjunction with time-of-flight measurements of the carrier mobilities, key structure,property relationships for these materials are re-established. [source] Charge transport in stacking metal and metal-free phthalocyanine iodides.JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 13 2009Effects of packing, central metals, core modification, dopants, external electric field, substitutions Abstract The charge-transport properties of the one-dimensional stacking metal phthalocyanine iodides (M(Pc)I, M = Fe, Co, Ni, Cu) and metal-free phthalocyanine iodide (H2(Pc)I) have been theoretically investigated. On the basis of the tight-binding approximation and two-state theory, both the site-energy corrected energy splitting in dimer and Fock-matrix-based methods are used to calculate the transfer integral. The intermolecular motions, including interplanar translation, rotation, slip, and tilt, exert remarkable impacts on the transfer integral. The order/disorder of the dopant stack and the long-range electrostatic interactions are also demonstrated to be crucial factors for modulation of charge-transport properties. The transfer integral undergoes slight changes under an applied electric field along the stacking direction in the range of 106 , 107 V cm,1. The change of central metals in MPc has little effect on the transfer integrals, but significantly affects the reorganization energies. The extension of the ,-conjugation in macrocyclic ligand brings about considerable influence on the transfer integrals. Peripheral substitutions by animo, hydroxyl, and methyl lead to deviations from planarity of macromolecular rings, and hence affect the valence bands significantly. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 [source] The Origin of the Improved Efficiency and Stability of Triphenylamine-Substituted Anthracene Derivatives for OLEDs: A Theoretical Investigation,CHEMPHYSCHEM, Issue 17 2008Bing Yang Dr. Abstract Herein, we describe the molecular electronic structure, optical, and charge-transport properties of anthracene derivatives computationally using density functional theory to understand the factors responsible for the improved efficiency and stability of organic light-emitting diodes (OLEDs) with triphenylamine (TPA)-substituted anthracene derivatives. The high performance of OLEDs with TPA-substituted anthracene is revealed to derive from three original features in comparison with aryl-substituted anthracene derivatives: 1) the HOMO and LUMO are localized separately on TPA and anthracene moieties, respectively, which leads to better stability of the OLEDs due to the more stable cation of TPA under a hole majority-carrier environment; 2) the more balanceable hole and electron transport together with the easier hole injection leads to a larger rate of hole,electron recombination, which corresponds to the higher electroluminescence efficiency; and 3) the increasing reorganization energy for both hole and electron transport and the higher HOMO energy level provide a stable potential well for hole trapping, and then trapped holes induce a built-in electric field to prompt the balance of charge-carrier injection. [source] Intrachain versus Interchain Electron Transport in Poly(fluorene- alt -benzothiadiazole): A Quantum-Chemical InsightCHEMPHYSCHEM, Issue 7 2008Antoine Van Vooren Abstract Poly(9,9-di- n -octylfluorene- alt -benzothiadiazole) [F8BT], displays very different charge-transport properties for holes versus electrons when comparing annealed and pristine thin films and transport parallel (intrachain) and perpendicular (interchain) to the polymer axes. The present theoretical contribution focuses on the electron-transport properties of F8BT chains and compares the efficiency of intrachain versus interchain transport in the hopping regime. The theoretical results rationalize significantly lowered electron mobility in annealed F8BT thin films and the smaller mobility anisotropy (,,/,,) measured for electrons in aligned films (i.e. 5,7 compared to 10,15 for holes). [source] Electroluminescent Diodes from Complementary Discotic BenzoperylenesCHEMPHYSCHEM, Issue 9 2003Sonia Alibert-Fouet Dr. Unequal brothers: Benzoperylene carboxylic acid derivatives with flexible chains not only form charge-transporting columnar liquid crystals (see graphic), their charge-transport properties can also be tuned to be either of n - or of p -type: relatively minor changes in the substitution pattern yield different materials that are complementary enough to form red-fluorescent charge-transfer complexes and p,n junction electronic devices. [source] | |||||||||||||