| 1. |
- Andersson, Peter, et al.
(författare)
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Printable All-Organic Electrochromic Active-Matrix Displays
- 2007
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 17:16, s. 3074-3082
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Tidskriftsartikel (refereegranskat)abstract
- All-organic active matrix addressed displays based on electrochemical smart pixels made on flexible substrates are reported. Each individual smart pixel device combines an electrochemical transistor with an electrochromic display cell, thus resulting in a low-voltage operating and robust display technology. Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) served as the active material in the electrochemical smart pixels, as well as the conducting lines, of the monolithically integrated active-matrix display. Different active-matrix display addressing schemes have been investigated and a matrix display fill factor of 65 % was reached. This is achieved by combining a three-terminal electrochemical transistor with an electrochromic display cell architecture, in which an additional layer of PEDOT:PSS was placed on top of the display cell counter electrode. In addition, we have evaluated different kinds of electrochromic polymer materials aiming at reaching a high color switch contrast. This work has been carried out in the light of achieving a robust display technology that is easily manufactured using a standard label printing press, which forced us to use the fewest different materials as well as avoiding exotic and complex device architectures. Together, this yields a manufacturing process of only five discrete patterning steps, which in turn promise for that the active matrix addressed displays can be manufactured on paper or plastic substrates in a roll-to-roll production procedure.
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| 2. |
- Dick Thelander, Kimberly, et al.
(författare)
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A new understanding of au-assisted growth of III-V semiconductor nanowires
- 2005
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 15:10, s. 1603-1610
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires of III-V materials have generated much interest in recent years. However, the growth mechanisms by which these structures form are not well understood. The so-called vapor-liquid-solid (VLS) mechanism has often been proposed for III-V systems, with a chemically inert, liquid metal particle (typically Au) acting as a physical catalyst. We assert here that An is, in fact, not inert with respect to the semiconductor material but rather interacts with it to form a variety of intermetallic compounds. Moreover, we suggest that III-V nanowire growth can best be understood if the metallic particle is not a liquid, but a solid-phase solution or compound containing An and the group III material. The four materials GaP, GaAs, InP, and InAs will be considered, and growth behavior related to their particular temperature-dependent interaction with Au.
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| 3. |
- Fan, Chaxing, et al.
(författare)
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Formation of chiral mesopores in conducting polymers by chiral lipid ribbon templating and “seeding” route
- 2008
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 18:18, s. 2699-2707
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Tidskriftsartikel (refereegranskat)abstract
- Conducting polymer nanofibers with controllable chiral mesopores in the size, the shape, and handedness have been synthesized by chiral lipid ribbon templating and “seeding” route. Chiral mesoporous conducting poly(pyrrole) (CMPP) synthesized with very small amount of chiral amphiphilic molecules (usually < 3%) has helically twisted channels with well-defined controllable pore size of 5–20 nm in central axis of the twisted fibers. The structure and chirality of helical mesopores have been characterized by high-resolution transmission electron microscope (HRTEM), scanning electron microscope (SEM) and electron tomography. The average pore diameters of chiral mesopores were approximately estimated from the N2 adsorption–desorption data and calculated by the conversion calculation from helical ribbons to a rectangular straight tape. The pore size of CMPP has been controlled by choosing different alkyl chain lengths of chiral lipid molecules or precisely adjusting the H2O/EtOH volume ratio.
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| 4. |
- Fang, Junfeng, et al.
(författare)
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The design and realization of flexible light-emitting electrochemical cells with record-long lifetime
- 2009
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 19:16, s. 2671-2676
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Tidskriftsartikel (refereegranskat)abstract
- Polymer light-emitting electrochemical cells (LECs) offer an attractive opportunity for low-cost production of functional devices in flexible and large-area configurations, but the critical drawback in comparison to competing light-emission technologies is a limited operational lifetime. Here, it is demonstrated that it is possible to improve the lifetime by straightforward and motivated means from a typical value of a few hours to more than one month of uninterrupted operation at significant brightness (>100 cd m−2) and relatively high power conversion efficiency (2 lm W−1 for orange-red emission). Specifically, by optimizing the composition of the active material and by employing an appropriate operational protocol, a desired doping structure is designed and detrimental chemical and electrochemical side reactions are identified and minimized. Moreover, the first functional flexible LEC with a similar promising device performance is demonstrated.
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| 5. |
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| 6. |
- Lafitte, Benoit, et al.
(författare)
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Proton-conducting aromatic polymers carrying hypersulfonated side chains for fuel cell applications
- 2007
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 17:15, s. 2823-2834
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Tidskriftsartikel (refereegranskat)abstract
- Polysulfone main chains have been functionalized with hypersulfonated aromatic side chains where the sulfonic acid groups were highly concentrated on a local scale, with two acid groups placed on the same aromatic ring. This molecular design was implemented to promote the nanophase separation that takes place in proton-exchange membranes between the hydrophobic polymer main chain and the hydrophilic ionic groups responsible for the water uptake and conduction. Morphological investigations revealed that polysulfones functionalized with disulfonaphthoxybenzoyl or trisulfopyrenoxybenzoyl side chains contained larger and more uniform ionic clusters, as compared to conventionally sulfonated polysulfones where the acid groups are dispersed along the main chain. Membranes based on the polymers carrying hypersulfonated side chains formed efficient networks of water-filled nanopores upon hydration, which facilitated excellent levels of proton conductivity exceeding that of the commercial Nafion membrane at moderate water uptakes.
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| 7. |
- Larsson, Oscar, 1978-, et al.
(författare)
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Insulator Polarization Mechanisms in Polyelectrolyte-Gated Organic Field-Effect Transistors
- 2009
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Ingår i: Advanced Functional Materials. - : Wiley InterScience. - 1616-301X .- 1616-3028. ; 19:20, s. 3334-3341
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Tidskriftsartikel (refereegranskat)abstract
- Electrolyte-gated organic field-effect transistors (OFETs) hold promise for robust printed electronics operating at low voltages. The polarization mechanism of thin solid electrolyte films, the gate insulator in such OFETs, is still unclear and appears to limit the transient current characteristics of the transistors. Here, the polarization response of a thin proton membrane, a poly(styrenesulfonic acid) film, is controlled by varying the relative humidity. The formation of the conducting transistor channel follows the polarization of the polyelectrolyte, such that the drain transient current characteristics versus the time are rationalized by three different polarization mechanisms: the dipolar relaxation at high frequencies, the ionic relaxation (migration) at intermediate frequencies, and the electric double-layer formation at the polyelectrolyte interfaces at low frequencies. The electric double layers of polyelectrolyte capacitors are formed in 1 µs at humid conditions and an effective capacitance per area of 10 µF cm-2 is obtained at 1 MHz, thus suggesting that this class of OFETs might operate at up to 1 MHz at 1 V.
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| 8. |
- Li, Shanghua, et al.
(författare)
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Nature-inspired boiling enhancement by novel nanostructured macroporous surfaces
- 2008
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 18:15, s. 2215-2220
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Tidskriftsartikel (refereegranskat)abstract
- World energy crisis has triggered more attention to energy saving and energy conversion systems. Enhanced surfaces for boiling are among the applications of great interest since they can improve the energy efficiency of heat pumping equipment (i.e., air conditioners, heat pumps, refrigeration machines). Methods that are used to make the state-of-the-art enhanced Surfaces are often based on complicated mechanical machine tools, are quite material-consuming and give limited enhancement of the boiling heat transfer. Here, we present a new approach to fabricate enhanced surfaces by using a simple electrodeposition method with in-situ grown dynamic gas bubble templates. As a result, a well-ordered 3D macro-porous metallic surface layer with nanostructured porosity is obtained. Since the structure is built based on the dynamic bubbles, it is perfect for the bubble generation applications Such as nucleate boiling. At heat flux of 1W cm(-2), the heat transfer coefficient is enhanced over 17 times compared to a plain reference Surface. It's estimated that such ail effective boiling surface Would improve the energy efficiency of many heat Pumping machines with 10-30%. The extraordinary boiling performance is explained based on the structure characteristics.
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| 9. |
- Mak, Wing Cheung, et al.
(författare)
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Diffusion controlled and temperature stable microcapsule reaction compartments for high throughput microcapsule-PCR
- 2008
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Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 18:19, s. 2930-2937
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Tidskriftsartikel (refereegranskat)abstract
- A novel approach to perform a high number of individual polymerase chain reactions (PCR) in microcapsule reaction compartments, termed “Microcapsule-PCR” was developed. Temperature stable microcapsules with a selective permeable capsule wall were constructed by matrix-assisted layer-by-layer (LbL) Encapsulation technique. During the PCR, small molecular weight building blocks – nucleotides (dNTPs) were supplied externally and diffuse through the permeable capsule wall into the interior, while the resulted high molecular weight PCR products were accumulated within the microcapsule. Microcapsules (∼110.8 µm average diameter) filled with a PCR reaction mixture were constructed by an emulsion technique having a 2% agarose core and a capsule formed by LbL coating with poly(allylamine-hydrochloride) and poly(4-styrene-sulfonate). An encapsulation efficiency of 47% (measured for primer-FITC (22 bases)) and 98% PCR efficiency was achieved. Microcapsules formed by eight layers of polyelectrolyte and subjected to PCR cycling (up to 95 °C) demonstrated good temperature stability without any significantly changes in DNA retention yield and microcapsule morphology. A multiplex Microcapsule-PCR experiment demonstrated that microcapsules are individual compartment and do not exchange templates or primers between microcapsules during PCR cycling.
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| 10. |
- Mantovani Nardes, Alexandre, et al.
(författare)
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A morphological model for the solvent-enhanced conductivity of PEDOT : PSS thin films
- 2008
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlag. - 1616-301X .- 1616-3028. ; 18:6, s. 865-871
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Tidskriftsartikel (refereegranskat)abstract
- The well-known enhanced conductivity of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin films that is obtained by addition of high-boiling solvents like sorbitol to the aqueous dispersion used for film deposition is shown to be associated with a rearrangement of PEDOT-rich clusters into elongated domains, as evidenced from STM and AFM. Consistently, temperature dependent conductivity measurements for sorbitol-treated films reveal that charge transport occurs via quasi ID variable range hopping (VRH), in contrast to 3D VRH for untreated PEDOT:PSS films. The typical hopping distance of 60-90 nm, extracted from the conductivity measurements is consistent with hopping between the 30-40 nm sized grains observed with scanning probe microscopy.
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