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Layer Leads (layer + lead)
Selected AbstractsA Delivery System for Self-Healing Inorganic Films,ADVANCED FUNCTIONAL MATERIALS, Issue 22 2008Harvey A. Liu Abstract Multilayer composites that utilize polymeric and brittle inorganic films are essential components for extending the lifetimes and exploiting the flexibility of many electronic devices. However, crack formation within the brittle inorganic layers that arise from defects as well as the flexing of these multilayer composite materials allows the influx of atmospheric water, a major source of device degradation. Thus, a composite material that can initiate self-healing upon the influx of environmental water through defects or stress-induced cracks would find potential applications in multilayer composite materials for permeation barriers. In the present study, the reactive metal oxide precursor TiCl4 is encapsulated within the pores of a degradable polymer, poly(lactic acid) (PLA). Electrospun PLA fibers are found to be reactive to atmospheric water leading to the hydrolysis of the degradable polymer shell and subsequent release of the reactive metal oxide precursor. Release of the reactive TiCl4 from the pores results in hydrolysis of the metal oxide precursor, forming solid titanium oxides at the surface of the fibers. The efficacy of this self-healing delivery system is also demonstrated by the integration of these reactive fibers in the polymer planarization layer, poly(methyl methacrylate), of a multilayer film, upon which an alumina barrier layer is deposited. The introduction of nanocracks in the alumina barrier layer lead to the release of the metal oxide precursor from the pores of the fibers and the formation of titanium dioxide nanoparticles within the crack and upon the thin film surface. In this study the first delivery system that may find utility for the self-healing of multilayer barrier films through the site-specific delivery of metal oxide nanoparticles through smart reactive composite fibers is established. [source] Red-Emitting Polyfluorenes Grafted with Quinoline-Based Iridium Complex: "Simple Polymeric Chain, Unexpected High Efficiency"ADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Zhihua Ma Abstract A series of red-light emitting electrophosphorescent polyfluorenes (PFs) with varying content of a quinoline-based iridium complex, (PPQ)2Ir(acac) (bis(2,4-diphenylquinolyl-N,C2,) iridium(acetylacetonate)), in the side chain are synthesized by Suzuki polycondensation. Because of the efficient Förster energy transfer from the PF main chain to (PPQ)2Ir(acac) and direct charge trapping on the complex, the electroluminescent emission from PF is nearly completely quenched, even though the amount of iridium complex incorporated into the polymers is as low as 1,mol %. Based on a single-layer device configuration, a luminous efficiency of up to 5.0,cd A,1 with a luminance of 2000,cd m,2 and Commission Internationale de L'Eclairage coordinates of (0.63, 0.35) (x, y) is realized, which is far superior to that of previously reported red-light emitting PFs containing benzothiazole- and isoquinoline-based iridium complexes. This result is beyond expectations, especially when considering that the simple polymeric chain involved has no additional charge-transporting moieties. Noticeably, the device efficiency remains as high as 4.2,cd A,1 with a luminance of 4000,cd m,2 even at current densities of 100,mA cm,2. Further optimization of the device configuration by incorporating an additional electron-injection layer leads to improved efficiencies of 8.3 and 7.5,cd A,1 at luminances of 100 and 1000,cd m,2, respectively. This state-of-the-art performance indicates that covalently attaching quinoline-based iridium complexes to a PF backbone is a simple and effective strategy to develop high-efficiency red-light emitting electrophosphorescent polymers. [source] Densification of Oxide Nanoparticle Thin Films by Irradiation with Visible LightADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Massimo F. Bertino Abstract A technique is presented that allows for altering of the physical characteristics of films of TiO2 nanoparticles by exposure to visible light. In this technique, dye-sensitized oxide nanoparticles are deposited on a substrate by dip-coating. Photodissociation of the organic ligand layer leads to cross-linking of the nanoparticles. Consequently, irradiated films have a decreased porosity, an increased index of refraction and an increased hydrophobicity. Films irradiated with green light are compared to films irradiated with UV light. Within experimental error, visible- and UV-illumination induces the same changes in the films. The mechanism of surfactant elimination in dye-sensitized oxide particles is discussed, patterning is demonstrated, and prospective applications of the technique are considered. [source] Volumetric methods for evaluating energy loss and heat transfer in cavity flows,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2007Stuart Norris Abstract Methods have been developed for calculating irreversible energy losses and rates of heat transfer from computational fluid dynamics solutions using volume integrations of energy dissipation or entropy production functions. These methods contrast with the more usual approach of performing first law energy balances over the boundaries of a flow domain. Advantages of the volumetric approach are that the estimates involve the whole flow domain and are hence based on more information than would otherwise be used, and that the energy dissipation or entropy production functions allow for detailed assessment of the mechanisms and regions of energy loss or entropy production. Volume integrations are applied to the calculation of viscous losses in a lid-driven cavity flow, and to the viscous losses and heat transfer due to natural convection in a side-heated cavity. In the convection problem comparison with the entropy increase across a stationary heat conducting layer leads to a novel volume integral expression for the Nusselt number. The predictions using this method compare well with traditional surface integrals and benchmark results. Copyright © 2007 John Wiley & Sons, Ltd. [source] A comparative investigation of the damage build-up in GaN and Si during rare earth ion implantationPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2008Florence Gloux Abstract The medium range implantation of rare earth ions at room temperature in GaN layers leads to the formation of point defect clusters, basal and prismatic stacking faults from the lowest fluence. When a threshold fluence of about 3 × 1015 at/cm2 is reached, a highly disordered ,nanocrystalline layer' (NL) is observed to form at the surface. This layer is made of a mixture of misoriented nanocrystallites and voids. Beyond this NL, I1, I2 and E basal stacking faults (BSFs) have been identified, as well as in GaN implanted at lower fluences than the threshold. Prismatic stacking faults (PSFs) with Drum atomic configuration connect the I1 BSFs. A similar investigation of the damage in Eu implanted Si shows a completely different behaviour; in this case, from the relatively low fluence 1 × 1014 at/cm2, amorphization starts in patches at the projected range and extends very rapidly towards the surface and the bulk, to form a uniform amorphous layer already at 2 × 1014 at/cm2. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ce and Yb doped InP layers grown for radiation detectionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2007J. Zavadil Abstract InP single crystals were grown by liquid phase epitaxy on semi-insulating InP:Fe substrate with cerium (Ce) and ytterbium (Yb) additions to the growth melt. Grown layers were characterised by Hall measurements and low temperature photoluminescence spectroscopy. Both types of layers exhibit the change of electrical conductivity from n to p type. Ce and Yb have been found to be incorporated into the InP lattice since a sharp luminescence lines arising from inner shell transitions of Yb3+ and Ce3+ were detected at 1002 and 3534 nm, respectively. A metastable conductivity state of InP:Ce layers has been found at temperatures below 35 K, a phenomenon previously reported for InP:Yb layers. Similar electrical behaviour of InP (Ce, Yb) layers leads us to conclude that Ce acts as dominant acceptor impurity responsible for n,p conductivity change. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||