| 1. |
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| 2. |
- Christensen, Beth A., et al.
(författare)
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Late Miocene Onset of Tasman Leakage and Southern Hemisphere Supergyre Ushers in Near-Modern Circulation
- 2021
-
Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 48:18
-
Tidskriftsartikel (refereegranskat)abstract
- This study provides a Miocene-to-recent history of Tasman Leakage (TL), driving surface-to-intermediate waters from the Pacific into the Indian Ocean. TL, in addition to Indonesian ThroughFlow (ITF), constitutes an important part of the Southern Hemisphere Supergyre. Here, we employ deep-sea benthic delta C-13 timeseries from the southwestern Pacific and eastern Indian Oceans to identify the history of Tasman Leakage. The delta C-13 results combined with sedimentary evidence show that an inter-ocean connection south of Australia existed from 7 Ma onward. A southward shift in Westerlies combined with a northward movement of Australia created the oceanic corridor necessary for Tasman Leakage (between Australia and the sub-Antarctic Front) at this time. Furthermore, changes in the northern limb of the Supergyre (ITF) are evident in the sedimentary record on Broken Ridge from similar to 3 to 2 Ma when Banda Sea intermediate waters started originating from the North Pacific.
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| 3. |
- Craighero, Mariavittoria, 1995, et al.
(författare)
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Impact of Oligoether Side-Chain Length on the Thermoelectric Properties of a Polar Polythiophene
- 2024
-
Ingår i: ACS Applied Electronic Materials. - : AMER CHEMICAL SOC. - 2637-6113. ; 6:5, s. 2909-2916
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Forskningsöversikt (refereegranskat)abstract
- Conjugated polymers with oligoether side chains make up a promising class of thermoelectric materials. In this work, the impact of the side-chain length on the thermoelectric and mechanical properties of polythiophenes is investigated. Polymers with tri-, tetra-, or hexaethylene glycol side chains are compared, and the shortest length is found to result in thin films with the highest degree of order upon doping with the p-dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F(4)TCNQ). As a result, a stiff material with an electrical conductivity of up to 830 +/- 15 S cm(-1) is obtained, resulting in a thermoelectric power factor of about 21 mu W m(-1) K-2 in the case of as-cast films. Aging at ambient conditions results in an initial decrease in thermoelectric properties but then yields a highly stable performance for at least 3 months, with values of about 200 S cm(-1) and 5 mu W m(-1) K-2. Evidently, identification of the optimal side-chain length is an important criterion for the design of conjugated polymers for organic thermoelectrics.
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| 4. |
- Diaz de Zerio Mendaza, Amaia, 1986, et al.
(författare)
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Neat C60:C70 buckminsterfullerene mixtures enhance polymer solar cell performance
- 2014
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 2:35, s. 14354-14359
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that bulk-heterojunction blends based on neat, unsubstituted buckminsterfullerenes (C60, C70) and a thiophene–quinoxaline copolymer (TQ1) can be readily processed from solution. Atomic force and transmission electron microscopy as well as photoluminescence spectroscopy reveal that thin films with a fine-grained nanostructure can be spin-coated, which display a good photovoltaic performance. Replacement of substituted fullerenes with C60 or C70 only results in a small drop in open-circuit voltage from 0.9 V to about 0.8 V. Thus, a power conversion efficiency of up to 2.9% can be maintained if C70 is used as the acceptor material. Further improvement in photovoltaic performance to 3.6% is achieved, accompanied by a high internal quantum efficiency of 75%, if a 1 : 1 C60:C70 mixture is used as the acceptor material, due to its improved solubility in ortho-dichlorobenzene.
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| 5. |
- Dyson, M., et al.
(författare)
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Structure/Property/Processing Relationships for Organic Solar Cells
- 2018
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Ingår i: RSC Nanoscience and Nanotechnology. - : The Royal Society of Chemistry. - 1757-7136. - 9781782626749 ; 2018-January:45, s. 182-225
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Rapid developments in the field of organic solar cells have been driven by this technology's potentially advantageous traits: the environmentally friendly, low-cost generation of energy with the possibility of large area manufacturing of flexible, lightweight, semi-transparent devices, with predicted low energy payback times. Major step changes leading to vastly improved devices with ever-increasing performance have been achieved through new insights into materials design and an improved understanding of the often complex microstructure and phase morphology of organic solar cell systems. This chapter summarises the advances in synthesis, concentrating on the relevant structure/property relations and how the chemical structure affects processing and the microstructure. This is followed by a detailed discussion of classical materials science approaches that assist in gaining insights into complex materials systems, such as organic solar cell blends from the molecular to the micrometre scale, with a focus on polymer-based systems and how to apply this knowledge to future larger area processing of organic photovoltaic architectures.
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| 6. |
- Enquist, Henrik, et al.
(författare)
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FemtoMAX - An X-ray beamline for structural dynamics at the short-pulse facility of MAX IV
- 2018
-
Ingår i: Journal of Synchrotron Radiation. - 0909-0495. ; 25:2, s. 570-579
-
Tidskriftsartikel (refereegranskat)abstract
- The FemtoMAX beamline facilitates studies of the structural dynamics of materials. Such studies are of fundamental importance for key scientific problems related to programming materials using light, enabling new storage media and new manufacturing techniques, obtaining sustainable energy by mimicking photosynthesis, and gleaning insights into chemical and biological functional dynamics. The FemtoMAX beamline utilizes the MAX IV linear accelerator as an electron source. The photon bursts have a pulse length of 100fs, which is on the timescale of molecular vibrations, and have wavelengths matching interatomic distances (Å). The uniqueness of the beamline has called for special beamline components. This paper presents the beamline design including ultrasensitive X-ray beam-position monitors based on thin Ce:YAG screens, efficient harmonic separators and novel timing tools.The FemtoMAX beamline facilitates studies of the structural dynamics of materials on the femtosecond timescale. The first commissioning results are presented.
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| 7. |
- Fu, Michael, 1963, et al.
(författare)
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Trends in myocarditis incidence, complications and mortality in Sweden from 2000 to 2014.
- 2022
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Investigate trends in myocarditis incidence and prognosis in Sweden during 2000-2014. Little data exist concerning population-trends in incidence of hospitalizations for myocarditis and subsequent prognosis. Linking Swedish National Patient and Cause of Death Registers, we identified individuals≥16years with first-time diagnosis of myocarditis during 2000-2014. Reference population, matched for age and birth year (n=16,622) was selected from Swedish Total Population Register. Among the 8 679 cases (75% men, 64%<50years), incidence rate/100,000 inhabitants rose from 6.3 to 8.6 per 100,000, mostly in men and those<50years. Incident heart failure/dilated cardiomyopathy occurred in 6.2% within 1year after index hospitalization and in 10.2% during 2000-2014, predominantly in those≥50years (12.1% within 1year, 20.8% during 2000-2014). In all 8.1% died within 1year, 0.9% (<50years) and 20.8% (≥50years). Hazard ratios (adjusted for age, sex) for 1-year mortality comparing cases and controls were 4.00 (95% confidence interval 1.37-11.70), 4.48 (2.57-7.82), 4.57 (3.31-6.31) and 3.93 (3.39-4.57) for individuals aged<30, 30 to<50, 50 to<70, and≥70years, respectively. The incidence of myocarditis during 2000-2014 increased, predominantly in men<50years. One-year mortality was low, but fourfold higher compared with reference population.
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| 8. |
- George, Zandra, 1985, et al.
(författare)
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The Influence of Alkoxy Substitutions on the Properties of Diketopyrrolopyrrole-Phenyl Copolymers for Solar Cells
- 2013
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 6:7, s. 3022-3034
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Tidskriftsartikel (refereegranskat)abstract
- A previously reported diketopyrrolopyrrole (DPP)-phenyl copolymer is modified by adding methoxy or octyloxy side chains on the phenyl spacer. The influence of these alkoxy substitutions on the physical, opto-electronic properties, and photovoltaic performance were investigated. It was found that the altered physical properties correlated with an increase in chain flexibility. Well-defined oligomers were synthesized to verify the observed structure-property relationship. Surprisingly, methoxy substitution on the benzene spacer resulted in higher melting and crystallization temperatures in the synthesized oligomers. This trend is not observed in the polymers, where the improved interactions are most likely counteracted by the larger conformational possibilities in the polymer chain upon alkoxy substitution. The best photovoltaic performance was obtained for the parent polymer: fullerene blends whereas the modifications on the other two polymers result in reduced open-circuit voltage and varying current densities under similar processing conditions. The current densities could be related to different polymer: fullerene blend morphologies. These results show that supposed small structural alterations such as methoxy substitution already significantly altered the physical properties of the parent polymer and also that oligomers and polymers respond divergent to structural alterations made on a parent structure.
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| 9. |
- Grytsan, Andrii, 1986-
(författare)
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Abdominal aortic aneurysm inception and evolution - A computational model
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Abdominal aortic aneurysm (AAA) is characterized by a bulge in the abdominal aorta. AAA development is mostly asymptomatic, but such a bulge may suddenly rupture, which is associated with a high mortality rate. Unfortunately, there is no medication that can prevent AAA from expanding or rupturing. Therefore, patients with detected AAA are monitored until treatment indication, such as maximum AAA diameter of 55 mm or expansion rate of 1 cm/year. Models of AAA development may help to understand the disease progression and to inform decision-making on a patient-specific basis. AAA growth and remodeling (G&R) models are rather complex, and before the challenge is undertaken, sound clinical validation is required.In Paper A, an existing thick-walled model of growth and remodeling of one layer of an AAA slice has been extended to a two-layered model, which better reflects the layered structure of the vessel wall. A parameter study was performed to investigate the influence of mechanical properties and G&R parameters of such a model on the aneurysm growth.In Paper B, the model from Paper A was extended to an organ level model of AAA growth. Furthermore, the model was incorporated into a Fluid-Solid-Growth (FSG) framework. A patient-specific geometry of the abdominal aorta is used to illustrate the model capabilities.In Paper C, the evolution of the patient-specific biomechanical characteristics of the AAA was investigated. Four patients with five to eight Computed Tomography-Angiography (CT-A) scans at different time points were analyzed. Several non-trivial statistical correlations were found between the analyzed parameters.In Paper D, the effect of different growth kinematics on AAA growth was investigated. The transverse isotropic in-thickness growth was the most suitable AAA growth assumption, while fully isotropic growth and transverse isotropic in-plane growth produced unrealistic results. In addition, modeling of the tissue volume change improved the wall thickness prediction, but still overestimated thinning of the wall during aneurysm expansion.
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| 10. |
- Henriksson, Patrik, 1983, et al.
(författare)
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Stability study of quinoxaline and pyrido pyrazine based co-polymers for solar cell applications
- 2014
-
Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 130, s. 138-143
-
Tidskriftsartikel (refereegranskat)abstract
- We present two co-polymer families; one based on a thiophene-quinoxaline unit and one on a thiophene-pyrido pyrazine unit. Co-polymerization of these monomers with thiophene-hexylthiophene was performed to create polymers with an optical absorption that fully covers the visible part of the solar spectrum with the aim to enhance the solar cell performances of these polymers. We have also studied how increasing the fraction of thiophene-hexylthiophene affects the photo-oxidative stability of these polymers. Thiophene-pyrido pyrazine solar cells displayed increased device efficiency upon addition of the thiophene-hexylthiophene and, in addition, the stability is retained upon inclusion of these units. In contrast, we found that for the thiophene-quinoxaline based co-polymer, both device efficiency and stability decreased with increasing thiophene-hexylthiophene fraction. Moreover, our results indicate that the photo-oxidative stability of the thiophene-quinoxaline co-polymer is independent of the polymer molecular weight as well as of the film thickness.
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| 11. |
- Hofmann, Anna, 1987, et al.
(författare)
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Chemical Doping of Conjugated Polymers with the Strong Oxidant Magic Blue
- 2020
-
Ingår i: Advanced Electronic Materials. - : Wiley. - 2199-160X .- 2199-160X. ; 6:8
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular doping of organic semiconductors is a powerful tool for the optimization of organic electronic devices and organic thermoelectric materials. However, there are few redox dopants that have a sufficiently high electron affinity to allow the doping of conjugated polymers with an ionization energy of more than 5.3 eV. Here, p-doping of a broad palette of conjugated polymers with high ionization energies is achieved by using the strong oxidant tris(4-bromophenyl)ammoniumyl hexachloroantimonate (Magic Blue). In particular diketopyrrolopyrrole (DPP)-based copolymers reach a conductivity of up to 100 S cm−1 and a thermoelectric power factor of 10 µW m−1 K−2. Further, both electron paramagnetic resonance (EPR) as well as a combination of spectroelectrochemistry and chronoamperometry is used to estimate the charge-carrier density of the polymer PDPP-3T doped with Magic Blue. A molar attenuation coefficient of 6.0 ± 0.2 × 103 m2 mol−1 is obtained for the first polaronic sub-bandgap absorption of electrochemically oxidized PDPP-3T. Comparison with chemically doped PDPP-3T suggests a charge-carrier density on the order of 1026 m−3, which yields a charge-carrier mobility of up to 0.5 cm2 V−1 s−1 for the most heavily doped material.
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| 12. |
- Hofmann, Anna, 1987, et al.
(författare)
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Doping and processing of organic semiconductors for plastic thermoelectrics
- 2018
-
Ingår i: Handbook of Organic Materials for Electronic and Photonic Devices, Second Edition. - 9780081022849 ; , s. 429-449
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Thermoelectrics currently attracts considerable attention as a promising branch in the field of organic electronics, with the prospect that organic semiconductors (OSCs) allow the development of light, flexible, and inexpensive thermoelectric devices, which act as alternative power sources, generating electricity from heat gradients. Thermoelectric generators are solid-state devices that convert heat directly to electricity. They do not contain any moving parts and are able to operate over an extended period of time, and furthermore can function with small heat sources and limited temperature differences, which facilitates their use in situations where traditional engines are not feasible. The absence of moving parts, low need for maintenance, and a large variety of possible device architectures render organic thermoelectrics attractive for numerous applications, ranging from waste heat recovery to wearable textiles. In this chapter, we give a short introduction to the fundamentals of the thermoelectric effect, as well as to the design principles for thermoelectric generators and their characterization. Furthermore, we discuss the role of doping (i.e., the introduction of charge carriers through the addition of dopant molecules) and of the nanostructure and present strategies for the optimization of the thermoelectric properties of OSCs. Finally, we give an overview of processing methods and point out major achievements, as well as the remaining challenges.
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| 13. |
- Hofmann, Anna, 1987, et al.
(författare)
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Highly stable doping of a polar polythiophene through co-processing with sulfonic acids and bistriflimide
- 2018
-
Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7534 .- 2050-7526. ; 6:26, s. 6905-6910
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Tidskriftsartikel (refereegranskat)abstract
- Doping of organic semiconductors is currently an intensely studied field, since it is a powerful tool to optimize the performance of various organic electronic devices, ranging from organic solar cells, to thermoelectric modules, and bio-medical sensors. Despite recent advances, there is still a need for the development of highly conducting polymer: dopant systems with excellent long term stability and a high resistance to elevated temperatures. In this work we study the doping of the polar polythiophene derivative p(g(4)2T-T) by various sulfonic acids and bistriflimide via different processing techniques. We demonstrate that simple co-processing of p(g(4)2T-T) with an acid dopant yields conductivities of up to 120 S cm(-1), which remain stable for more than six months under ambient conditions. Notably, a high conductivity is only achieved if the doping is carried out in air, which can be explained with a doping process that involves an acid mediated oxidation of the polymer through O-2. P(g(4)2T-T) doped with the non-toxic and inexpensive 1,3-propanedisulfonic acid was found to retain its electrical conductivity for at least 20 hours upon annealing at 120 degrees C, which allowed the bulk processing of the doped polymer into conducting, free-standing and flexible films and renders the di-acid a promising alternative to commonly used redox dopants.
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| 14. |
- Holmes, N. P., et al.
(författare)
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Nano-pathways: Bridging the divide between water-processable nanoparticulate and bulk heterojunction organic photovoltaics
- 2016
-
Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855. ; 19, s. 495-510
-
Tidskriftsartikel (refereegranskat)abstract
- Here we report the application of a conjugated copolymer based on thiophene and quinoxaline units, namely poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-di yl] (TQ1), to nanoparticle organic photovoltaics (NP-OPVs). TQ1 exhibits more desirable material properties for NP-OPV fabrication and operation, particularly a high glass transition temperature (T-g) and amorphous nature, compared to the commonly applied semicrystalline polymer poly(3-hexylthiophene) (P3HT). This study reports the optimisation of TQ1:PC71BM (phenyl C-71 butyric acid methyl ester) NP-OPV device performance by the application of mild thermal annealing treatments in the range of the T-g (sub-T-g and post-T-g), both in the active layer drying stage and post-cathode deposition annealing stage of device fabrication, and an in-depth study of the effect of these treatments on nanoparticle film morphology. In addition, we report a type of morphological evolution in nanoparticle films for OPV active layers that has not previously-been observed, that of PC71BM nano-pathway formation between dispersed PC71BM-rich nanoparticle cores, which have the benefit of making the bulk film more conducive to charge percolation and extraction.
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| 15. |
- Hultmark, Sandra, 1994, et al.
(författare)
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Impact of oxidation-induced ordering on the electrical and mechanical properties of a polythiophene co-processed with bistriflimidic acid
- 2022
-
Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 11:24, s. 8091-8099
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Tidskriftsartikel (refereegranskat)abstract
- The interplay between the nanostructure of a doped polythiophene with oligoether side chains and its electrical as well as mechanical properties is investigated. The degree of order of the polymer is found to strongly vary when co-processed with bistriflimidic acid (H-TFSI). The neat polythiophene as well as strongly oxidized material are largely disordered while intermediate concentrations of H-TFSI give rise to a high degree of π-stacking. The structural disorder of strongly oxidized material correlates with a decrease in the kinetic fragility with H-TFSI concentration, suggesting that positive interactions between TFSI anions and the polymer reduce the ability to crystallize. The electrical conductivity as well as the Young's modulus first increase upon the addition of 4-10 mol% of H-TFSI, while the loss of π-stacking observed for strongly oxidized material more significantly affects the latter. As a result, material comprising 25 mol% H-TFSI displays an electrical conductivity of 58 S cm−1 but features a relatively low Young's modulus of only 80 MPa. Decoupling of the electrical and mechanical properties of doped conjugated polymers may allow the design of soft conductors that are in high demand for wearable electronics and bioelectronics.
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| 16. |
- Hynynen, Jonna, 1987, et al.
(författare)
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Enhanced Electrical Conductivity of Molecularly p-Doped Poly(3-hexylthiophene) through Understanding the Correlation with Solid-State Order
- 2017
-
Ingår i: Macromolecules. - : AMER CHEMICAL SOC. - 0024-9297 .- 1520-5835. ; 50:20, s. 8140-8148
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular p-doping of the conjugated polymer poly(3-hexylthiophene) (P3HT) with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ) is a widely studied model system. Underlying structure property relationships are poorly understood because processing and doping are often carried out simultaneously. Here, we exploit doping from the vapor phase, which allows us to disentangle the influence of processing and doping. Through this approach, we are able to establish how the electrical conductivity varies with regard to a series of predefined structural parameters. We demonstrate that improving the degree of solid-state order, which we control through the choice of processing solvent and regioregularity, strongly increases the electrical conductivity. As a result, we achieve a value of up to 12.7 S cm(-2) for P3HT:F4TCNQ, We determine the F4TCNQ anion concentration and find that the number of (bound + mobile) charge carriers of about 10(-4) mol cm(-3) is not influenced by the degree of solid-state order. Thus, the observed increase in electrical conductivity by almost 2 orders of magnitude can be attributed to an increase in charge-carrier mobility to more than 10(-1) cm(2) V-1 s(-1). Surprisingly, in contrast to charge transport in undoped P3HT, we find that the molecular weight of the polymer does not strongly influence the electrical conductivity, which highlights the need for studies that elucidate structure property relationships of strongly doped conjugated polymers.
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| 17. |
- Hynynen, Jonna, 1987, et al.
(författare)
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Enhanced Thermoelectric Power Factor of Tensile Drawn Poly(3-hexylthiophene)
- 2019
-
Ingår i: ACS Macro Letters. - : American Chemical Society (ACS). - 2161-1653. ; 8:1, s. 70-76
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 American Chemical Society. The thermoelectric power factor of a broad range of organic semiconductors scales with their electrical conductivity according to a widely obeyed power law, and therefore, strategies that permit this empirical trend to be surpassed are highly sought after. Here, tensile drawing of the conjugated polymer poly(3-hexylthiophene) (P3HT) is employed to create free-standing films with a high degree of uniaxial alignment. Along the direction of orientation, sequential doping with a molybdenum tris(dithiolene) complex leads to a 5-fold enhancement of the power factor beyond the predicted value, reaching up to 16 μW m-1 K-2 for a conductivity of about 13 S cm-1. Neither stretching nor doping affect the glass transition temperature of P3HT, giving rise to robust free-standing materials that are of interest for the design of flexible thermoelectric devices.
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| 18. |
- Islam, Md Shafiqul, 1984-
(författare)
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Fracture and Delamination in Packaging Materials : A Study of Experimental Methods and Simulation Techniques
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Packages are the means of preservation, distribution and convenience of use for food, medicine and other consumer products. The introduction of a new package-opening technique for a better opening experience requires additional prototype development and physical testing. In order for the design process to be more rapid and robust, finite element (FE) simulations are widely used in packaging industries to compliment and reduce the amount of physical testing.The goal of this work is to develop some building blocks for complete package-opening FE-simulation. To begin with, the study focuses on mechanical testing of packaging materials’ fracture and delamination; especially shear fracture. Use of tools like digital image correlation (DIC) and scanning electron microscope (SEM) greatly aided to the strain measuring technique and observation of fractured and delaminated surfaces respectively.A modified shear test specimen for polymer sheet testing was developed and its geometry was optimized by FE-simulation. A geometry correction factor of shear fracture toughness for the proposed specimen was derived based on linear elastic fracture mechanics (LEFM). It was found that the specimen ligament length should vary between twice the thickness and half the ligament width of the modified shear specimen to measure the essential work of fracture.Thin-flexible laminate of low-density polyethylene (LDPE) and aluminium (Al) is another key packaging material addressed in this study. The continuum and fracture testing of individual layers provided the base information and input for FE-modelling. The FE-simulation material parameters were calibrated from the physical test response through inverse analysis. Identification process of the laminate interface fracture energy (Gc) from peel tests was studied experimentally and theoretically. A successful FE-simulation optimization framework using artificial neural network and genetic algorithm was developed for the calibration of Gc. To address the challenge in quantifying shear Gc of laminate with very thin substrates, a convenient test technique was proposed. In a separate case, the tearing response of LDPE/PET (polyethylene terephthalate) laminate was studied to examine crack propagation, crack path deviation and delamination of the laminate in mode III fracture. Several tear EWF evaluation theories were proposed along with a cyclic tear test method.
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| 19. |
- Jarvid, Markus, 1985, et al.
(författare)
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A New Application Area for Fullerenes: Voltage Stabilizers for Power Cable Insulation
- 2015
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 27:5, s. 897-902
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Tidskriftsartikel (refereegranskat)abstract
- Fullerenes are shown to be efficient voltage-stabilizers for polyethylene, i.e., additives that increase the dielectric strength of the insulation material. Such compounds are highly sought-after because their use in power-cable insulation may considerably enhance the transmission efficiency of tomorrow's power grids. On a molal basis, fullerenes are the most efficient voltage stabilizers reported to date.
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| 20. |
- Järsvall, Emmy, 1992, et al.
(författare)
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Double Doping of a Low-Ionization-Energy Polythiophene with a Molybdenum Dithiolene Complex
- 2022
-
Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 34:12, s. 5673-5679
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Tidskriftsartikel (refereegranskat)abstract
- Doping of organic semiconductors is crucial for tuning the charge-carrier density of conjugated polymers. The exchange of more than one electron between a monomeric dopant and an organic semiconductor allows the polaron density to be increased relative to the number of counterions that are introduced into the host matrix. Here, a molybdenum dithiolene complex with a high electron affinity of 5.5 eV is shown to accept two electrons from a polythiophene that has a low ionization energy of 4.7 eV. Double p-doping is consistent with the ability of the monoanion salt of the molybdenum dithiolene complex to dope the polymer. The transfer of two electrons to the neutral dopant was also confirmed by electron paramagnetic resonance spectroscopy since the monoanion, but not the dianion, of the molybdenum dithiolene complex features an unpaired electron. Double doping allowed an ionization efficiency of 200% to be reached, which facilitates the design of strongly doped semiconductors while lessening any counterion-induced disruption of the nanostructure.
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| 21. |
- Kiefer, David, 1989, et al.
(författare)
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Double doping of conjugated polymers with monomer molecular dopants
- 2019
-
Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 18:2, s. 149-155
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular doping is a crucial tool for controlling the charge-carrier concentration in organic semiconductors. Each dopant molecule is commonly thought to give rise to only one polaron, leading to a maximum of one donor:acceptor charge-transfer complex and hence an ionization efficiency of 100%. However, this theoretical limit is rarely achieved because of incomplete charge transfer and the presence of unreacted dopant. Here, we establish that common p-dopants can in fact accept two electrons per molecule from conjugated polymers with a low ionization energy. Each dopant molecule participates in two charge-transfer events, leading to the formation of dopant dianions and an ionization efficiency of up to 200%. Furthermore, we show that the resulting integer charge-transfer complex can dissociate with an efficiency of up to 170%. The concept of double doping introduced here may allow the dopant fraction required to optimize charge conduction to be halved.
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| 22. |
- Kimpel, Joost, 1996, et al.
(författare)
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High-mobility organic mixed conductors with a low synthetic complexity index via direct arylation polymerization
- 2024
-
Ingår i: Chemical Science. - : ROYAL SOC CHEMISTRY. - 2041-6539 .- 2041-6520. ; 15:20, s. 7679-7688
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Tidskriftsartikel (refereegranskat)abstract
- Through direct arylation polymerization, a series of mixed ion-electron conducting polymers with a low synthetic complexity index is synthesized. A thieno[3,2-b]thiophene monomer with oligoether side chains is used in direct arylation polymerization together with a wide range of aryl bromides with varying electronic character from electron-donating thiophene to electron-accepting benzothiadiazole. The obtained polymers are less synthetically complex than other mixed ion-electron conducting polymers due to higher yield, fewer synthetic steps and less toxic reagents. Organic electrochemical transistors (OECTs) based on a newly synthesized copolymer comprising thieno[3,2-b]thiophene with oligoether side chains and bithiophene exhibit excellent device performance. A high charge-carrier mobility of up to μ = 1.8 cm2 V−1 s−1 was observed, obtained by dividing the figure of merit [μC*] from OECT measurements by the volumetric capacitance C* from electrochemical impedance spectroscopy, which reached a value of more than 215 F cm−3
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| 23. |
- Kroon, Renee, 1982, et al.
(författare)
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A New Tetracyclic Lactam Building Block for Thick, Broad-Bandgap Photovoltaics
- 2014
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 136:33, s. 11578-11581
-
Tidskriftsartikel (refereegranskat)abstract
- A new tetracyclic lactam building block for polymer semiconductors is reported that was designed to combine the many favorable properties that larger fused and/or amide-containing building blocks can induce, including improved solid-state packing, high charge carrier mobility, and improved charge separation. Copolymerization with thiophene resulted in a semicrystalline conjugated polymer, PTNT, with a broad bandgap of 2.2 eV. Grazing incidence wide-angle X-ray scattering of PTNT thin films revealed a strong tendency for face-on pi-stacking of the polymer backbone, which was retained in PTNT:firllerene blends. Corresponding solar cells featured a high open-circuit voltage of 0.9 V, a fill factor around 0.6, and a power conversion efficiency as high as 596 for greater than200 nm thick active layers, regardless of variations in blend stoichiometry and nanostructure. Moreover, efficiencies of greater than4% could be retained when thick active layers of similar to 400 rim were employed. Overall, these values are the highest reported for a conjugated polymer with such a broad bandgap and are unprecedented in materials for tandem and particularly ternary blend photovoltaics. Hence, the newly developed tetracyclic lactam unit has significant potential as a conjugated building block in future organic electronic materials.
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| 24. |
- Kroon, Renee, 1982, et al.
(författare)
-
Bulk Doping of Millimeter-Thick Conjugated Polymer Foams for Plastic Thermoelectrics
- 2017
-
Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 27:47
-
Tidskriftsartikel (refereegranskat)abstract
- Foaming of plastics allows for extensive tuning of mechanical and physicochemical properties. Utilizing the foam architecture for plastic semiconductors can be used to improve ingression of external molecular species that govern the operation of organic electronic devices. In case of plastic thermoelectrics, utilizing solid semiconductors with realistic (millimeter (mm)-thick) dimensions does not permit sequential doping—while sequential doping offers the higher thermoelectric performance compared to other methods—because this doping methodology is diffusion limited. In this work, a fa brication process for poly(3-hexylthiophene) (P3HT) foams is presented, based on a combination of salt leaching and thermally induced phase separation. The obtained micro- and nanoporous architecture permits rapid and uniform doping of mm-thick foams with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, while thick solid P3HT structures suffer from protracted doping times and a dopant-depleted central region. Importantly, the thermoelectric performance of a P3HT foam is largely retained when normalized with regard to the quantity of used material.
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| 25. |
- Kroon, Renee, 1982, et al.
(författare)
-
Comparison of selenophene and thienothiophene incorporation into pentacyclic lactam-based conjugated polymers for organic solar cells
- 2015
-
Ingår i: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 6:42, s. 7402-7409
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we compare the effect of incorporating selenophene versus thienothiophene spacers into pentacyclic lactam-based conjugated polymers for organic solar cells. The two cyclic lactam-based copolymers were obtained via a new synthetic method for the lactam moiety. Selenophene incorporation results in a broader and red-shifted optical absorption while retaining a deep highest occupied molecular orbital level, whereas thienothienophene incorporation results in a blue-shifted optical absorption. Additionally, grazing-incidence wide angle X-ray scattering data indicates edge- and face-on solid state order for the selenophene-based polymer as compared to the thienothiophene-based polymer, which orders predominantly edge-on with respect to the substrate. In polymer : PC71BM bulk heterojunction solar cells both materials show a similar open-circuit voltage of similar to 0.80-0.84 V, however the selenophene-based polymer displays a higher fill factor of similar to 0.70 vs. similar to 0.65. This is due to the partial face-on backbone orientation of the selenophene-based polymer, leading to a higher hole mobility, as confirmed by single-carrier diode measurements, and a concomitantly higher fill factor. Combined with improved spectral coverage of the selenophene-based polymer, as confirmed by quantum efficiency experiments, it offers a larger short-circuit current density of similar to 12 mA cm(-2). Despite the relatively low molecular weight of both materials, a very robust power conversion efficiency similar to 7% is achieved for the selenophene-based polymer, while the thienothiophene-based polymer demonstrates only a moderate maximum PCE of similar to 5.5%. Hence, the favorable effects of selenophene incorporation on the photovoltaic performance of pentacyclic lactam-based conjugated polymers are clearly demonstrated.
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| 26. |
- Kroon, Renee, 1982, et al.
(författare)
-
New quinoxaline and pyridopyrazine-based polymers for solution-processable photovoltaics
- 2012
-
Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 105, s. 280-286
-
Tidskriftsartikel (refereegranskat)abstract
- The recently published quinoxaline/thiophene-based polymer TQ1 has been modified on its acceptor unit, either altering the acceptor strength by incorporating a pyridopyrazine, substitution of the acceptor-hydrogens by fluorine, or substitution of the alkoxy side chain by alkyl. The changes in physical, electronic and device properties are discussed. For the polymers incorporating the stronger acceptors a decreased performance is found, where in both cases the current in the devices is compromised. Incorporation of the pyridopyrazine-based acceptor seems to result in more severe or additional loss mechanisms compared to the polymer that incorporates the fluorine atoms. A similar performing material is obtained when changing the alkoxy side chain in TQ1 to an alkyl, where the solar cell performance is mainly improved on the fill factor. It is demonstrated that the standard TQ1 structure is easily modified in a number of ways, showing the versatility and robustness of the standard TQ1 structure and synthesis.
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| 27. |
- Kroon, Renee, 1982, et al.
(författare)
-
Polar Side Chains Enhance Processability, Electrical Conductivity, and Thermal Stability of a Molecularly p-Doped Polythiophene.
- 2017
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 29:24, s. 1700930-
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular doping of organic semiconductors is critical for optimizing a range of optoelectronic devices such as field-effect transistors, solar cells, and thermoelectric generators. However, many dopant:polymer pairs suffer from poor solubility in common organic solvents, which leads to a suboptimal solid-state nanostructure and hence low electrical conductivity. A further drawback is the poor thermal stability through sublimation of the dopant. The use of oligo ethylene glycol side chains is demonstrated to significantly improve the processability of the conjugated polymer p(g4 2T-T)-a polythiophene-in polar aprotic solvents, which facilitates coprocessing of dopant:polymer pairs from the same solution at room temperature. The use of common molecular dopants such as 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is explored. Doping of p(g4 2T-T) with F4TCNQ results in an electrical conductivity of up to 100 S cm(-1) . Moreover, the increased compatibility of the polar dopant F4TCNQ with the oligo ethylene glycol functionalized polythiophene results in a high degree of thermal stability at up to 150 °C.
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| 28. |
- Kroon, Renee, 1982, et al.
(författare)
-
Thermally Activated in Situ Doping Enables Solid-State Processing of Conducting Polymers
- 2019
-
Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 31:8, s. 2770-2777
-
Tidskriftsartikel (refereegranskat)abstract
- Free-standing bulk structures encompassing highly doped conjugated polymers are currently heavily explored for wearable electronics as thermoelectric elements, conducting fibers, and a plethora of sensory devices. One-step manufacturing of such bulk structures is challenging because the interaction of dopants with conjugated polymers results in poor solution and solid-state processability, whereas doping of thick conjugated polymer structures after processing suffers from diffusion-limited transport of the dopant. Here, we introduce the concept of thermally activated latent dopants for in situ bulk doping of conjugated polymers. Latent dopants allow for noninteractive coprocessing of dopants and polymers, while thermal activation eliminates any thickness-dependent diffusion and activation limitations. Two latent acid dopants were synthesized in the form of thermal acid generators based on aryl sulfonic acids and an o-nitrobenzyl capping moiety. First, we show that these acid dopant precursors can be coprocessed noninteractively with three different polythiophenes. Second, the polymer films were doped in situ through thermal activation of the dopants. Ultimately, we demonstrate that solid-state processing with a latent acid dopant can be readily carried out and that it is possible to dope more than 100 μm-thick polymer films through thermal activation of the latent dopant.
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| 29. |
- Kroon, Renee, 1982, et al.
(författare)
-
Thermoelectric plastics: from design to synthesis, processing and structure-property relationships
- 2016
-
Ingår i: Chemical Society Reviews. - : Royal Society of Chemistry (RSC). - 1460-4744 .- 0306-0012. ; 45:22, s. 6147-6164
-
Forskningsöversikt (refereegranskat)abstract
- Thermoelectric plastics are a class of polymer-based materials that combine the ability to directly convert heat to electricity, and vice versa, with ease of processing. Potential applications include waste heat recovery, spot cooling and miniature power sources for autonomous electronics. Recent progress has led to surging interest in organic thermoelectrics. This tutorial review discusses the current trends in the field with regard to the four main building blocks of thermoelectric plastics: (1) organic semiconductors and in particular conjugated polymers, (2) dopants and counterions, (3) insulating polymers, and (4) conductive fillers. The design and synthesis of conjugated polymers that promise to show good thermoelectric properties are explored, followed by an overview of relevant structure-property relationships. Doping of conjugated polymers is discussed and its interplay with processing as well as structure formation is elucidated. The use of insulating polymers as binders or matrices is proposed, which permit the adjustment of the rheological and mechanical properties of a thermoelectric plastic. Then, nanocomposites of conductive fillers such as carbon nanotubes, graphene and inorganic nanowires in a polymer matrix are introduced. A case study examines poly(3,4-ethylenedioxythiophene) (PEDOT) based materials, which up to now have shown the most promising thermoelectric performance. Finally, a discussion of the advantages provided by bulk architectures e.g. for wearable applications highlights the unique advantages that thermoelectric plastics promise to offer.
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| 30. |
- Lindqvist, Camilla, 1985, et al.
(författare)
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Fullerene Nucleating Agents: A Route Towards Thermally Stable Photovoltaic Blends
- 2014
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6840 .- 1614-6832. ; 4:9, s. 1301437-
-
Tidskriftsartikel (refereegranskat)abstract
- The bulk-heterojunction nanostructure of non-crystalline polymer: fullerene blends has the tendency to rapidly coarsen when heated above its glass transition temperature, which represents an important degradation mechanism. We demonstrate that fullerene nucleating agents can be used to thermally arrest the nanostructure of photovoltaic blends that comprise a non-crystalline thiophene-quinoxaline copolymer and the widely used fullerene derivative [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM). To this end, C-60 fullerene is employed to efficiently nucleate PCBM crystallization. Sub-micrometer-sized fullerene crystals are formed when as little as 2 wt% C-60 with respect to PCBM is added to the blend. These reach an average size of only 200 nanometers upon introduction of more than 8 wt% C-60. Solar cells based on C-60-nucleated blends indicate significantly improved thermal stability of the bulk-heterojunction nanostructure even after annealing at an elevated temperature of 130 degrees C, which lies above the glass transition temperature of the blend. Moreover, we find that various other compounds, including C-70 fullerene, single-walled carbon nanotubes, and sodium benzoate, as well as a number of commercial nucleating agents-commonly used to clarify isotactic polypropylene-permit to control crystallization of the fullerene phase.
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| 31. |
- Mone, Mariza, 1992, et al.
(författare)
-
Mechanically Adaptive Mixed Ionic-Electronic Conductors Based on a Polar Polythiophene Reinforced with Cellulose Nanofibrils
- 2023
-
Ingår i: ACS Applied Materials & Interfaces. - : AMER CHEMICAL SOC. - 1944-8252 .- 1944-8244. ; 15:23, s. 28300-28309
-
Tidskriftsartikel (refereegranskat)abstract
- Conjugated polymers with oligoether side chains are promising mixed ionic-electronic conductors, but they tend to feature a low glass transition temperature and hence a low elastic modulus, which prevents their use if mechanical robust materials are required. Carboxymethylated cellulose nanofibrils (CNF) are found to be a suitable reinforcing agent for a soft polythiophene with tetraethylene glycol side chains. Dry nanocomposites feature a Young’s modulus of more than 400 MPa, which reversibly decreases to 10 MPa or less upon passive swelling through water uptake. The presence of CNF results in a slight decrease in electronic mobility but enhances the ionic mobility and volumetric capacitance, with the latter increasing from 164 to 197 F cm-3 upon the addition of 20 vol % CNF. Overall, organic electrochemical transistors (OECTs) feature a higher switching speed and a transconductance that is independent of the CNF content up to at least 20 vol % CNF. Hence, CNF-reinforced conjugated polymers with oligoether side chains facilitate the design of mechanically adaptive mixed ionic-electronic conductors for wearable electronics and bioelectronics.
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| 32. |
- Moseng, Tuva, et al.
(författare)
-
EULAR recommendations for the non-pharmacological core management of hip and knee osteoarthritis : 2023 update
- 2024
-
Ingår i: Annals of the Rheumatic Diseases. - 1468-2060.
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Hip and knee osteoarthritis (OA) are increasingly common with a significant impact on individuals and society. Non-pharmacological treatments are considered essential to reduce pain and improve function and quality of life. EULAR recommendations for the non-pharmacological core management of hip and knee OA were published in 2013. Given the large number of subsequent studies, an update is needed.METHODS: The Standardised Operating Procedures for EULAR recommendations were followed. A multidisciplinary Task Force with 25 members representing 14 European countries was established. The Task Force agreed on an updated search strategy of 11 research questions. The systematic literature review encompassed dates from 1 January 2012 to 27 May 2022. Retrieved evidence was discussed, updated recommendations were formulated, and research and educational agendas were developed.RESULTS: The revised recommendations include two overarching principles and eight evidence-based recommendations including (1) an individualised, multicomponent management plan; (2) information, education and self-management; (3) exercise with adequate tailoring of dosage and progression; (4) mode of exercise delivery; (5) maintenance of healthy weight and weight loss; (6) footwear, walking aids and assistive devices; (7) work-related advice and (8) behaviour change techniques to improve lifestyle. The mean level of agreement on the recommendations ranged between 9.2 and 9.8 (0-10 scale, 10=total agreement). The research agenda highlighted areas related to these interventions including adherence, uptake and impact on work.CONCLUSIONS: The 2023 updated recommendations were formulated based on research evidence and expert opinion to guide the optimal management of hip and knee OA.
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| 33. |
- Persson, Gustav, 1993, et al.
(författare)
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Visualisation of individual dopants in a conjugated polymer : sub-nanometre 3D spatial distribution and correlation with electrical properties
- 2022
-
Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 14, s. 15404-15413
-
Tidskriftsartikel (refereegranskat)abstract
- While molecular doping is ubiquitous in all branches of organic electronics, little is known about the spatial distribution of dopants, especially at molecular length scales. Moreover, a homogeneous distribution is often assumed when simulating transport properties of these materials, even though the distribution is expected to be inhomogeneous. In this study, electron tomography is used to determine the position of individual molybdenum dithiolene complexes and their three-dimensional distribution in a semiconducting polymer at the sub-nanometre scale. A heterogeneous distribution is observed, the characteristics of which depend on the dopant concentration. At 5 mol% of the molybdenum dithiolene complex, the majority of the dopant species are present as isolated molecules or small clusters up to five molecules. At 20 mol% dopant concentration and higher, the dopant species form larger nanoclusters with elongated shapes. Even in case of these larger clusters, each individual dopant species is still in contact with the surrounding polymer. The electrical conductivity first strongly increases with dopant concentration and then slightly decreases for the most highly doped samples, even though no large aggregates can be observed. The decreased conductivity is instead attributed to the increased energetic disorder and lower probability of electron transfer that originates from the increased size and size variation in dopant clusters. This study highlights the importance of detailed information concerning the dopant spatial distribution at the sub-nanometre scale in three dimensions within the organic semiconductor host. The information acquired using electron tomography may facilitate more accurate simulations of charge transport in doped organic semiconductors.
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| 34. |
- Ryan, Jason, 1988, et al.
(författare)
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All-Organic Textile Thermoelectrics with Carbon-Nanotube-Coated n-Type Yarns
- 2018
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:6, s. 2934-2941
-
Tidskriftsartikel (refereegranskat)abstract
- Thermoelectric textiles that are able to generate electricity from heat gradients may find use as power sources for a wide range of miniature wearable electronics. To realize such thermoelectric textiles, both p- and n-type yarns are needed. The realization of air-stable and flexible n-type yarns, i.e., conducting yarns where electrons are the majority charge carriers, presents a considerable challenge due to the scarcity of air-stable n-doped organic materials. Here, we realize such n-type yarns by coating commercial sewing threads with a nanocomposite of multiwalled carbon nanotubes (MWNTs) and poly(N-vinylpyrrolidone) (PVP). Our n-type yarns have a bulk conductivity of 1 S cm -1 and a Seebeck coefficient of -14 μV K -1 , which is stable for several months at ambient conditions. We combine our coated n-type yarns with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) dyed silk yarns, constituting the p-type component, to realize a textile thermoelectric module with 38 n/p elements, which are capable of producing an open-circuit voltage of 143 mV when exposed to a temperature gradient of 116 °C and a maximum power output of 7.1 nW at a temperature gradient of 80 °C.
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| 35. |
- Sainz-Jaspeado, Miguel, et al.
(författare)
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Palmdelphin Regulates Nuclear Resilience to Mechanical Stress in the Endothelium
- 2021
-
Ingår i: Circulation. - : Wolters Kluwer. - 0009-7322 .- 1524-4539. ; 144:20, s. 1629-1645
-
Tidskriftsartikel (refereegranskat)abstract
- Background: PALMD (palmdelphin) belongs to the family of paralemmin proteins implicated in cytoskeletal regulation. Single nucleotide polymorphisms in the PALMD locus that result in reduced expression are strong risk factors for development of calcific aortic valve stenosis and predict severity of the disease.Methods: Immunodetection and public database screening showed dominant expression of PALMD in endothelial cells (ECs) in brain and cardiovascular tissues including aortic valves. Mass spectrometry, coimmunoprecipitation, and immunofluorescent staining allowed identification of PALMD partners. The consequence of loss of PALMD expression was assessed in small interferring RNA-treated EC cultures, knockout mice, and human valve samples. RNA sequencing of ECs and transcript arrays on valve samples from an aortic valve study cohort including patients with the single nucleotide polymorphism rs7543130 informed about gene regulatory changes.Results: ECs express the cytosolic PALMD-KKVI splice variant, which associated with RANGAP1 (RAN GTP hydrolyase activating protein 1). RANGAP1 regulates the activity of the GTPase RAN and thereby nucleocytoplasmic shuttling via XPO1 (Exportin1). Reduced PALMD expression resulted in subcellular relocalization of RANGAP1 and XPO1, and nuclear arrest of the XPO1 cargoes p53 and p21. This indicates an important role for PALMD in nucleocytoplasmic transport and consequently in gene regulation because of the effect on localization of transcriptional regulators. Changes in EC responsiveness on loss of PALMD expression included failure to form a perinuclear actin cap when exposed to flow, indicating lack of protection against mechanical stress. Loss of the actin cap correlated with misalignment of the nuclear long axis relative to the cell body, observed in PALMD-deficient ECs, Palmd(-/-) mouse aorta, and human aortic valve samples derived from patients with calcific aortic valve stenosis. In agreement with these changes in EC behavior, gene ontology analysis showed enrichment of nuclear- and cytoskeleton-related terms in PALMD-silenced ECs.Conclusions: We identify RANGAP1 as a PALMD partner in ECs. Disrupting the PALMD/RANGAP1 complex alters the subcellular localization of RANGAP1 and XPO1, and leads to nuclear arrest of the XPO1 cargoes p53 and p21, accompanied by gene regulatory changes and loss of actin-dependent nuclear resilience. Combined, these consequences of reduced PALMD expression provide a mechanistic underpinning for PALMD's contribution to calcific aortic valve stenosis pathology.
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| 36. |
- Stegerer, Dominik, 1988, et al.
(författare)
-
Organogels from Diketopyrrolopyrrole Copolymer Ionene/Polythiophene Blends Exhibit Ground-State Single Electron Transfer in the Solid State
- 2022
-
Ingår i: Macromolecules. - : American Chemical Society (ACS). - 1520-5835 .- 0024-9297. ; 55:12, s. 4979-4994
-
Tidskriftsartikel (refereegranskat)abstract
- Acceptor copolymers with low lowest unoccupied molecular orbital (LUMO) energy levels are key materials for organic electronics. In the present work, quaternization of pyridine-flanked diketopyrrolopyrrole (PyDPPPy) is used to lower the LUMO energy level of the resulting monomer (MePyDPPPy) by as much as 0.7 eV. The drastically changed electronic properties of MePyDPPPy hinder a second methylation step even in an excess of trimethyloxonium tetrafluoroborate and thereby give access to the asymmetric functionalization of N-heterocycle-flanked DPP building blocks. The corresponding n-type polymeric ionene PMePyDPPPyT2 with bithiophene as comonomer forms thixotropic organogels with the p-type polythiophene P(g42T-TT), indicative of specific cross-interactions between this couple of copolymers. Gelation of polymer blend solutions, which is absent for other couples of p-type/ n-type polymers, is of general interest for (co)processing and orientation of different electronic polymers simultaneously into films or filaments. Detailed optical and electronic characterization reveals that films processed from organogels exhibit ground-state electron transfer (GSET) enabled by suitably positioned highest occupied molecular orbital (HOMO) and LUMO energy levels of P(g42T-TT) (-4.07 eV) and PMePyDPPPyT2 (-4.20 eV), respectively. Furthermore, molecular interactions related to gelation and GSET do not appear to significantly influence the morphology of the polymer blend films.
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| 37. |
- Tugues, Sonia, et al.
(författare)
-
Tetraspanin CD63 Promotes Vascular Endothelial Growth Factor Receptor 2-beta 1 Integrin Complex Formation, Thereby Regulating Activation and Downstream Signaling in Endothelial Cells in Vitro and in Vivo
- 2013
-
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:26, s. 19060-19071
-
Tidskriftsartikel (refereegranskat)abstract
- CD63 is a member of the transmembrane-4 glycoprotein superfamily (tetraspanins) implicated in the regulation of membrane protein trafficking, leukocyte recruitment, and adhesion processes. We have investigated the involvement of CD63 in endothelial cell (EC) signaling downstream of beta 1 integrin and VEGF. We report that silencing of CD63 in primary ECs arrested capillary sprouting and tube formation in vitro because of impaired adhesion and migration of ECs. Mechanistically, CD63 associated with both beta 1 integrin and the main VEGF receptor on ECs, VEGFR2. Our data suggest that CD63 serves to bridge between beta 1 integrin and VEGFR2 because CD63 silencing disrupted VEGFR2-beta 1 integrin complex formation identified using proximity ligation assays. Signaling downstream of beta 1 integrin and VEGFR2 was attenuated in CD63-silenced cells, although their cell surface expression levels remained unaffected. CD63 was furthermore required for efficient internalization of VEGFR2 in response to VEGF. Importantly, systemic delivery of VEGF failed to potently induce VEGFR2 phosphorylation and downstream signaling in CD63-deficient mouse lungs. Taken together, our findings demonstrate a previously unrecognized role for CD63 in coordinated integrin and receptor tyrosine kinase signaling in vitro and in vivo.
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| 38. |
- Volkov, Anton V., et al.
(författare)
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Asymmetric Aqueous Supercapacitor Based on p- and n-Type Conducting Polymers
- 2019
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 2:8, s. 5350-5355
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrated an asymmetric aqueous supercapacitor made of p- and n-type conducting polymer electrodes. We used the high electron affinity (EA) n-type polymer poly(benzimidazobenzophenanthroline) (BBL) as the anode conducting material, and the low ionization potential (IP) p-type polar polythiophene p(g(4)2T-T) as the cathode material. EA(BBL) matches IPp(g42T-T), enabling the fabrication of all-organic asymmetric p/n-supercapacitors that function in aqueous electrolytes. The devices operate in a voltage window up to 1 V, yielding areal capacitances of 90 mF cm(-2) and specific capacitances of 33 F g(-1) as well as excellent cycling stability with almost 100% capacitance retention over 10 000 cycles.
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| 39. |
- Xu, Kai, et al.
(författare)
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Ground-state electron transfer in all-polymer donor-acceptor heterojunctions
- 2020
-
Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 19:7, s. 738-744
-
Tidskriftsartikel (refereegranskat)abstract
- Doping of organic semiconductors is crucial for the operation of organic (opto)electronic and electrochemical devices. Typically, this is achieved by adding heterogeneous dopant molecules to the polymer bulk, often resulting in poor stability and performance due to dopant sublimation or aggregation. In small-molecule donor–acceptor systems, charge transfer can yield high and stable electrical conductivities, an approach not yet explored in all-conjugated polymer systems. Here, we report ground-state electron transfer in all-polymer donor–acceptor heterojunctions. Combining low-ionization-energy polymers with high-electron-affinity counterparts yields conducting interfaces with resistivity values five to six orders of magnitude lower than the separate single-layer polymers. The large decrease in resistivity originates from two parallel quasi-two-dimensional electron and hole distributions reaching a concentration of ∼1013 cm–2. Furthermore, we transfer the concept to three-dimensional bulk heterojunctions, displaying exceptional thermal stability due to the absence of molecular dopants. Our findings hold promise for electro-active composites of potential use in, for example, thermoelectrics and wearable electronics.
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| 40. |
- Yang, Chi Yuan, et al.
(författare)
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Low-Power/High-Gain Flexible Complementary Circuits Based on Printed Organic Electrochemical Transistors
- 2022
-
Ingår i: Advanced Electronic Materials. - : Wiley. - 2199-160X .- 2199-160X. ; 8:3
-
Tidskriftsartikel (refereegranskat)abstract
- The ability to accurately extract low-amplitude voltage signals is crucial in several fields, ranging from single-use diagnostics and medical technology to robotics and the Internet of Things (IoT). The organic electrochemical transistor (OECT), which features large transconductance values at low operating voltages, is ideal for monitoring small signals. Here, low-power and high-gain flexible circuits based on printed complementary OECTs are reported. This work leverages the low threshold voltage of both p-type and n-type enhancement-mode OECTs to develop complementary voltage amplifiers that can sense voltages as low as 100 µV, with gains of 30.4 dB and at a power consumption of 0.1–2.7 µW (single-stage amplifier). At the optimal operating conditions, the voltage gain normalized to power consumption reaches 169 dB µW−1, which is >50 times larger than state-of-the-art OECT-based amplifiers. In a monolithically integrated two-stage configuration, these complementary voltage amplifiers reach voltage gains of 193 V/V, which are among the highest for emerging complementary metal-oxide-semiconductor-like technologies operating at supply voltages below 1 V. These flexible complementary circuits based on printed OECTs define a new power-efficient platform for sensing and amplifying low-amplitude voltage signals in several emerging beyond-silicon applications.
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| 41. |
- Yu, Liyang, 1986, et al.
(författare)
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Diffusion-Limited Crystallization: A Rationale for the Thermal Stability of Non-Fullerene Solar Cells
- 2019
-
Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244.
-
Tidskriftsartikel (refereegranskat)abstract
- © 2019 American Chemical Society. Organic solar cells are thought to suffer from poor thermal stability of the active layer nanostructure, a common belief that is based on the extensive work that has been carried out on fullerene-based systems. We show that a widely studied non-fullerene acceptor, the indacenodithienothiophene-based acceptor ITIC, crystallizes in a profoundly different way as compared to fullerenes. Although fullerenes are frozen below the glass-transition temperature Tg of the photovoltaic blend, ITIC can undergo a glass-crystal transition considerably below its high Tg of ∼180 °C. Nanoscopic crystallites of a low-temperature polymorph are able to form through a diffusion-limited crystallization process. The resulting fine-grained nanostructure does not evolve further with time and hence is characterized by a high degree of thermal stability. Instead, above Tg, the low temperature polymorph melts, and micrometer-sized crystals of a high-temperature polymorph develop, enabled by more rapid diffusion and hence long-range mass transport. This leads to the same detrimental decrease in photovoltaic performance that is known to occur also in the case of fullerene-based blends. Besides explaining the superior thermal stability of non-fullerene blends at relatively high temperatures, our work introduces a new rationale for the design of bulk heterojunctions that is not based on the selection of high-Tg materials per se but diffusion-limited crystallization. The planar structure of ITIC and potentially other non-fullerene acceptors readily facilitates the desired glass-crystal transition, which constitutes a significant advantage over fullerenes, and may pave the way for truly stable organic solar cells.
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| 42. |
- Yuan, Dafei, et al.
(författare)
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Double Doping of Semiconducting Polymers Using Ion-Exchange with a Dianion
- 2023
-
Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-3028 .- 1616-301X. ; 33:29
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Tidskriftsartikel (refereegranskat)abstract
- The interactions between counterions and electronic carriers in electrically doped semiconducting polymers are important for delocalization of charge carriers, electronic conductivity, and thermal stability. The introduction of a dianions in semiconducting polymers leads to double doping where there is one counterion for two charge carriers. Double doping minimizes structural distortions, but changes the electrostatic interactions between the carriers and counterions. Polymeric ionic liquids (PIL) with croconate dianions are helpful to investigate the role of the counterion in p-type semiconducting polymers. PILs prevent diffusion of the cation into the semiconducting polymers during ion exchange. The redox-active croconate dianions undergo ion exchange with doped semiconducting polymers depending on their ionization energy. Croconate dianions are found to reduce doped films of poly(3-hexyl thiophene), but undergo ion exchange with a polythiophene with tetraethylene glycol side chains, P(g42T-T), that has a lower ionization energy. The croconate dianion maintains crystalline order in P(g42T-T) and leads to a lower activation energy for the electrical conductivity than PF6− counterions. The control of the doping level with croconate allows optimization of the thermoelectric performance of the semiconducting polymer. The thermal stability of the doped films of P(g42T-T) is found to depend strongly on the nature of the counterion.
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| 43. |
- Zhang, Silan, et al.
(författare)
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Synergistic Effect of Multi-Walled Carbon Nanotubes and Ladder-Type Conjugated Polymers on the Performance of N-Type Organic Electrochemical Transistors
- 2022
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 32:1
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Tidskriftsartikel (refereegranskat)abstract
- Organic electrochemical transistors (OECTs) have the potential to revolutionize the field of organic bioelectronics. To date, most of the reported OECTs include p-type (semi-)conducting polymers as the channel material, while n-type OECTs are yet at an early stage of development, with the best performing electron-transporting materials still suffering from low transconductance, low electron mobility, and slow response time. Here, the high electrical conductivity of multi-walled carbon nanotubes (MWCNTs) and the large volumetric capacitance of the ladder-type π-conjugated redox polymer poly(benzimidazobenzophenanthroline) (BBL) are leveraged to develop n-type OECTs with record-high performance. It is demonstrated that the use of MWCNTs enhances the electron mobility by more than one order of magnitude, yielding fast transistor transient response (down to 15 ms) and high μC* (electron mobility × volumetric capacitance) of about 1 F cm−1 V−1 s−1. This enables the development of complementary inverters with a voltage gain of >16 and a large worst-case noise margin at a supply voltage of <0.6 V, while consuming less than 1 µW of power.
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| 44. |
- Zokaei, Sepideh, 1991, et al.
(författare)
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Electrically Conducting Elastomeric Fibers with High Stretchability and Stability
- 2022
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 18:5
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Tidskriftsartikel (refereegranskat)abstract
- Stretchable conducting materials are appealing for the design of unobtrusive wearable electronic devices. Conjugated polymers with oligoethylene glycol side chains are excellent candidate materials owing to their low elastic modulus and good compatibility with polar stretchable polymers. Here, electrically conducting elastomeric blend fibers with high stretchability, wet spun from a blend of a doped polar polythiophene with tetraethylene glycol side chains and a polyurethane are reported. The wet-spinning process is versatile, reproducible, scalable, and produces continuous filaments with a diameter ranging from 30 to 70 µm. The fibers are stretchable up to 480% even after chemical doping with iron(III) p-toluenesulfonate hexahydrate and exhibit an electrical conductivity of up to 7.4 S cm−1, which represents a record combination of properties for conjugated polymer-based fibers. The fibers remain conductive during elongation until fiber fracture and display excellent long-term stability at ambient conditions. Cyclic stretching up to 50% strain for at least 400 strain cycles reveals that the doped fibers exhibit high cyclic stability and retain their electrical conductivity. Finally, a directional strain sensing device, which makes use of the linear increase in resistance of the fibers up to 120% strain is demonstrated.
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| 45. |
- Zokaei, Sepideh, 1991, et al.
(författare)
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Toughening of a Soft Polar Polythiophene through Copolymerization with Hard Urethane Segments
- 2021
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Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- Polar polythiophenes with oligoethylene glycol side chains are exceedingly soft materials. A low glass transition temperature and low degree of crystallinity prevents their use as a bulk material. The synthesis of a copolymer comprising 1) soft polythiophene blocks with tetraethylene glycol side chains, and 2) hard urethane segments is reported. The molecular design is contrary to that of other semiconductor-insulator copolymers, which typically combine a soft nonconjugated spacer with hard conjugated segments. Copolymerization of polar polythiophenes and urethane segments results in a ductile material that can be used as a free-standing solid. The copolymer displays a storage modulus of 25 MPa at room temperature, elongation at break of 95%, and a reduced degree of swelling due to hydrogen bonding. Both chemical doping and electrochemical oxidation reveal that the introduction of urethane segments does not unduly reduce the hole charge-carrier mobility and ability to take up charge. Further, stable operation is observed when the copolymer is used as the active layer of organic electrochemical transistors.
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| 46. |
- Zokaei, Sepideh, 1991, et al.
(författare)
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Tuning of the elastic modulus of a soft polythiophene through molecular doping
- 2022
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Ingår i: Materials Horizons. - : Royal Society of Chemistry (RSC). - 2051-6355 .- 2051-6347. ; 9:1, s. 433-443
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Tidskriftsartikel (refereegranskat)abstract
- Molecular doping of a polythiophene with oligoethylene glycol side chains is found to strongly modulate not only the electrical but also the mechanical properties of the polymer. An oxidation level of up to 18% results in an electrical conductivity of more than 52 S cm(-1) and at the same time significantly enhances the elastic modulus from 8 to more than 200 MPa and toughness from 0.5 to 5.1 MJ m(-3). These changes arise because molecular doping strongly influences the glass transition temperature T-g and the degree of pi-stacking of the polymer, as indicated by both X-ray diffraction and molecular dynamics simulations. Surprisingly, a comparison of doped materials containing mono- or dianions reveals that - for a comparable oxidation level - the presence of multivalent counterions has little effect on the stiffness. Evidently, molecular doping is a powerful tool that can be used for the design of mechanically robust conducting materials, which may find use within the field of flexible and stretchable electronics.
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