| 1. |
- Acker, Pascal, et al.
(författare)
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π-Conjugation Enables Ultra-High Rate Capabilities and Cycling Stabilities in Phenothiazine Copolymers as Cathode-Active Battery Materials
- 2019
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Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 29:45
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, organic battery cathode materials have emerged as an attractive alternative to metal oxide–based cathodes. Organic redox polymers that can be reversibly oxidized are particularly promising. A drawback, however, often is their limited cycling stability and rate performance in a high voltage range of more than 3.4 V versus Li/Li+. Herein, a conjugated copolymer design with phenothiazine as a redox‐active group and a bithiophene co‐monomer is presented, enabling ultra‐high rate capability and cycling stability. After 30 000 cycles at a 100C rate, >97% of the initial capacity is retained. The composite electrodes feature defined discharge potentials at 3.6 V versus Li/Li+ due to the presence of separated phenothiazine redox centers. The semiconducting nature of the polymer allows for fast charge transport in the composite electrode at a high mass loading of 60 wt%. A comparison with three structurally related polymers demonstrates that changing the size, amount, or nature of the side groups leads to a reduced cell performance. This conjugated copolymer design can be used in the development of advanced redox polymers for batteries.
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| 2. |
- Ail, Ujwala, et al.
(författare)
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Thermoelectric Properties of Polymeric Mixed Conductors
- 2016
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlagsgesellschaft. - 1616-301X .- 1616-3028. ; 26:34, s. 6288-6296
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Tidskriftsartikel (refereegranskat)abstract
- The thermoelectric (TE) phenomena are intensively explored by the scientific community due to the rather inefficient way energy resources are used with a large fraction of energy wasted in the form of heat. Among various materials, mixed ion-electron conductors (MIEC) are recently being explored as potential thermoelectrics, primarily due to their low thermal conductivity. The combination of electronic and ionic charge carriers in those inorganic or organic materials leads to complex evolution of the thermovoltage (Voc) with time, temperature, and/or humidity. One of the most promising organic thermoelectric materials, poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS), is an MIEC. A previous study reveals that at high humidity, PEDOT-PSS undergoes an ionic Seebeck effect due to mobile protons. Yet, this phenomenon is not well understood. In this work, the time dependence of the Voc is studied and its behavior from the contribution of both charge carriers (holes and protons) is explained. The presence of a complex reorganization of the charge carriers promoting an internal electrochemical reaction within the polymer film is identified. Interestingly, it is demonstrated that the time dependence behavior of Voc is a way to distinguish between three classes of polymeric materials: electronic conductor, ionic conductor, and mixed ionic–electronic conductor
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| 3. |
- Altmann, Brigitte, et al.
(författare)
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Assessment of Novel Long-Lasting Ceria-Stabilized Zirconia-Based Ceramics with Different Surface Topographies as Implant Materials
- 2017
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlag. - 1616-301X .- 1616-3028. ; 27:40
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Tidskriftsartikel (refereegranskat)abstract
- The development of long-lasting zirconia-based ceramics for implants, which are not prone to hydrothermal aging, is not satisfactorily solved. Therefore, this study is conceived as an overall evaluation screening of novel ceria-stabilized zirconia-alumina-aluminate composite ceramics (ZA8Sr8-Ce11) with different surface topographies for use in clinical applications. Ceria-stabilized zirconia is chosen as the matrix for the composite material, due to its lower susceptibility to aging than yttria-stabilized zirconia (3Y-TZP). This assessment is carried out on three preclinical investigation levels, indicating an overall biocompatibility of ceria-stabilized zirconia-based ceramics, both in vitro and in vivo. Long-term attachment and mineralized extracellular matrix (ECM) deposition of primary osteoblasts are the most distinct on porous ZA8Sr8-Ce11p surfaces, while ECM attachment on 3Y-TZP and ZA8Sr8-Ce11 with compact surface texture is poor. In this regard, the animal study confirms the porous ZA8Sr8-Ce11p to be the most favorable material, showing the highest bone-to-implant contact values and implant stability post implantation in comparison with control groups. Moreover, the microbiological evaluation reveals no favoritism of biofilm formation on the porous ZA8Sr8-Ce11p when compared to a smooth control surface. Hence, together with the in vitro in vivo assessment analogy, the promising clinical potential of this novel ZA8Sr8-Ce11 as an implant material is demonstrated.
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| 4. |
- Asadpoordarvish, Amir, 1984-, et al.
(författare)
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Light-Emitting Paper
- 2015
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 25:21, s. 3238-3245
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Tidskriftsartikel (refereegranskat)abstract
- A solution-based fabrication of flexible and light-weight light-emitting devices on paper substrates is reported. Two different types of paper substrates are coated with a surface-emitting light-emitting electrochemical cell (LEC) device: a multilayer-coated specialty paper with an intermediate surface roughness of 0.4 μm and a low-end and low-cost copy paper with a large surface roughness of 5 μm. The entire device fabrication is executed using a handheld airbrush, and it is notable that all of the constituent layers are deposited from solution under ambient air. The top-emitting paper-LECs are highly flexible, and display a uniform light emission with a luminance of 200 cd m−2 at a current conversion efficacy of 1.4 cd A−1.
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| 5. |
- Bao, Qinye, et al.
(författare)
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Energy Level Bending in Ultrathin Polymer Layers Obtained through Langmuir-Shafer Deposition
- 2016
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Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 26:7, s. 1077-1084
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Tidskriftsartikel (refereegranskat)abstract
- The semiconductor-electrode interface impacts the function and the performance of (opto) electronic devices. For printed organic electronics the electrode surface is not atomically clean leading to weakly interacting interfaces. As a result, solution-processed organic ultrathin films on electrodes typically form islands due to dewetting. It has therefore been utterly difficult to achieve homogenous ultrathin conjugated polymer films. This has made the investigation of the correct energetics of the conjugated polymer-electrode interface impossible. Also, this has hampered the development of devices including ultrathin conjugated polymer layers. Here, LangmuirShafer-manufactured homogenous mono-and multilayers of semiconducting polymers on metal electrodes are reported and the energy level bending using photoelectron spectroscopy is tracked. The amorphous films display an abrupt energy level bending that does not extend beyond the first monolayer. These findings provide new insights of the energetics of the polymer-electrode interface and opens up for new high-performing devices based on ultrathin semiconducting polymers.
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| 6. |
- Chateau, Denis, et al.
(författare)
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Long Distance Enhancement of Nonlinear Optical Properties Using Low Concentration of Plasmonic Nanostructures in Dye Doped Monolithic Sol-Gel Materials.
- 2016
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Ingår i: Advanced Functional Materials. - Weinheim : Wiley. - 1616-301X .- 1616-3028. ; 26:33
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Tidskriftsartikel (refereegranskat)abstract
- Monolithic sol-gel silica composites incorporating platinum-based chromophores and various types of gold nanoparticles (AuNPs) are prepared and polished to high optical quality. Their photophysical properties are investigated. The glass materials show well-defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts of the AuNP plasmon absorption peaks due to the increase in nanoparticle doping concentration are observed in the glasses, proving that no or very small SPR coupling effects occur between the AuNPs. At 600 nm excitation, but not at 532 nm, the AuNPs improve the nonlinear absorption performance of glasses codoped with 50 × 10−3 m of a Pt-acetylide chromophore. The glasses doped with lower concentrations of AuNPs (2-5 μm average distance) and 50 × 10−3 m in chromophore, show a marked improvement in nonlinear absorption, with no or only small improvement for the more highly AuNP doped glasses. This study shows the importance of excitation wavelength and nanoparticle concentration for composite systems employing AuNPs to improve two-photon absorption of chromophores. [ABSTRACT FROM AUTHOR]
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| 7. |
- del Pozo, Freddy G., et al.
(författare)
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Single Crystal-Like Performance in Solution-Coated Thin-Film Organic Field-Effect Transistors
- 2016
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Ingår i: Advanced Functional Materials. - : Wiley-Blackwell. - 1616-301X .- 1616-3028. ; 26:14, s. 2379-2386
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Tidskriftsartikel (refereegranskat)abstract
- In electronics, the field-effect transistor (FET) is a crucial cornerstone and successful integration of this semiconductor device into circuit applications requires stable and ideal electrical characteristics over a wide range of temperatures and environments. Solution processing, using printing or coating techniques, has been explored to manufacture organic field-effect transistors (OFET) on flexible carriers, enabling radically novel electronics applications. Ideal electrical characteristics, in organic materials, are typically only found in single crystals. Tiresome growth and manipulation of these hamper practical production of flexible OFETs circuits. To date, neither devices nor any circuits, based on solution-processed OFETs, has exhibited an ideal set of characteristics similar or better than todays FET technology based on amorphous silicon. Here, bar-assisted meniscus shearing of dibenzo-tetrathiafulvalene to coat-process self-organized crystalline organic semiconducting domains with high reproducibility is reported. Including these coatings as the channel in OFETs, electric field and temperature-independent charge carrier mobility and no bias stress effects are observed. Furthermore, record-high gain in OFET inverters and exceptional operational stability in both air and water are measured.
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| 8. |
- Di Maria, Francesca, et al.
(författare)
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Controlling the Functional Properties of Oligothiophene Crystalline Nano/Microfibers via Tailoring of the Self-Assembling Molecular Precursors
- 2018
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Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 28:32
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Tidskriftsartikel (refereegranskat)abstract
- Oligothiophenes are π-conjugated semiconducting and fluorescent molecules whose self-assembly properties are widely investigated for application in organic electronics, optoelectronics, biophotonics, and sensing. Here an approach to the preparation of crystalline oligothiophene nano/microfibers is reported based on the use of a “sulfur overrich” quaterthiophene building block, T4S4 , containing in its covalent network all the information needed to promote the directional, π–π stacking-driven, self-assembly of Y-T4S4-Y oligomers into fibers with hierarchical supramolecular arrangement from nano- to microscale. It is shown that when Y varies from unsubstituted thiophene to thiophene substituted with electron-withdrawing groups, a wide redistribution of the molecular electronic charge takes place without substantially affecting the aggregation modalities of the oligomer. In this way, a structurally comparable series of fibers is obtained having progressively varying optical properties, redox potentials, photoconductivity, and type of prevailing charge carriers (from p- to n-type). With the aid of density functional theory (DFT) calculations, combined with powder X-ray diffraction data, a model accounting for the growth of the fibers from molecular to nano- and microscale is proposed
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| 9. |
- Doryab, Ali, et al.
(författare)
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Evolution of Bioengineered Lung Models : Recent Advances and Challenges in Tissue Mimicry for Studying the Role of Mechanical Forces in Cell Biology
- 2019
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028.
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Forskningsöversikt (refereegranskat)abstract
- Mechanical stretch under both physiological (breathing) and pathophysiological (ventilator-induced) conditions is known to significantly impact all cellular compartments in the lung, thereby playing a pivotal role in lung growth, regeneration and disease development. In order to evaluate the impact of mechanical forces on the cellular level, in vitro models using lung cells on stretchable membranes have been developed. Only recently have some of these cell-stretching devices become suitable for air–liquid interface cell cultures, which is required to adequately model physiological conditions for the alveolar epithelium. To reach this goal, a multi-functional membrane for cell growth balancing biophysical and mechanical properties is critical to mimic (patho)physiological conditions. In this review, i) the relevance of cyclic mechanical forces in lung biology is elucidated, ii) the physiological range for the key parameters of tissue stretch in the lung is described, and iii) the currently available in vitro cell-stretching devices are discussed. After assessing various polymers, it is concluded that natural-synthetic copolymers are promising candidates for suitable stretchable membranes used in cell-stretching models. This work provides guidance on future developments in biomimetic in vitro models of the lung with the potential to function as a template for other organ models (e.g., skin, vessels).
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| 10. |
- Edberg, Jesper, et al.
(författare)
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Patterning and Conductivity Modulation of Conductive Polymers by UV Light Exposure
- 2016
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Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 26:38, s. 6950-6960
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Tidskriftsartikel (refereegranskat)abstract
- A novel patterning technique of conductive polymers produced by vapor phase polymerization is demonstrated. The method involves exposing an oxidant film to UV light which changes the local chemical environment of the oxidant and subsequently the polymerization kinetics. This procedure is used to control the conductivity in the conjugated polymer poly(3,4-ethylenedioxythiophene): tosylate by more than six orders of magnitude in addition to producing high-resolution patterns and optical gradients. The mechanism behind the modulation in the polymerization kinetics by UV light irradiation as well as the properties of the resulting polymer are investigated.
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