| 1. |
- Krebs, Frederik C, et al.
(författare)
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A round robin study of flexible large-area roll-to-roll processed polymer solar cell modules
- 2009
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Ingår i: SOLAR ENERGY MATERIALS AND SOLAR CELLS. - : Elsevier BV. - 0927-0248. ; 93:11, s. 1968-1977
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Tidskriftsartikel (refereegranskat)abstract
- A round robin for the performance of roll-to-roll coated flexible large-area polymer solar-cell modules involving 18 different laboratories in Northern America, Europe and Middle East is presented. The study involved the performance measurement of the devices at one location (Riso DTU) followed by transportation to a participating laboratory for performance measurement and return to the starting location (Riso DTU) for re-measurement of the performance. It was found possible to package polymer solar-cell modules using a flexible plastic barrier material in such a manner that degradation of the devices played a relatively small role in the experiment that has taken place over 4 months. The method of transportation followed both air-mail and surface-mail paths.
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| 2. |
- Svensson, M., et al.
(författare)
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High-performance polymer solar cells of an alternating polyfluorene copolymer and a fullerene derivative
- 2003
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 15:12, s. 988-991
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Tidskriftsartikel (refereegranskat)abstract
- High-performance polymer solar cells of an alternating polyfluorene copolymer, PFDTBT, and a fullerene derivative were studied. It was shown that PFDTBT is a promising candidate for obtaining high energy conversion efficiency when combined with a suitable electron acceptor. Results showed that high-performance solar cells with extended spectral coverage and increased open-circuit voltage could be prepared from composites prepared from electron acceptor.
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| 3. |
- Kroon, Lars, et al.
(författare)
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Bifurcation picture and stability of the gap and out-gap discrete solitons
- 2007
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 33:5, s. 481-483
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of a quaternary fragment of a discrete system of coupled nonlinear oscillators with modulated frequency parameters is investigated, and the stability of its gap and out-gap soliton-like excitations is studied.
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| 4. |
- 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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| 5. |
- Hanås, Ragnar, 1951, et al.
(författare)
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Indwelling catheters used from the onset of diabetes decrease injection pain and pre-injection anxiety
- 2002
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Ingår i: J Pediatr. - : Elsevier BV. - 0022-3476 .- 0022-3476 .- 1097-6833. ; 140:3, s. 315-20
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To investigate the use of indwelling catheters as injection aids at diabetes onset to reduce injection pain and pre-injection anxiety. STUDY DESIGN: Forty-one patients aged 8.1 +/- 3.7 years (range, 1-15) participated in this open, controlled randomized study. A 10-cm VAS with faces was used for scoring. A local anesthetic cream was used before all insertions. The control group used insulin pens with standard needles. After one week, the indwelling catheter group could choose regular injections but were included in the "intention to treat" analysis. RESULTS: Injection pain and anxiety decreased from day 1 to 15 in both groups (average, 4.1 injections/day). Pain was significantly lower for indwelling catheter injections when scored by parents (median, 1.2 cm vs 2.7 cm; P =.002), children/teenagers (0.8 cm vs 1.5 cm; P =.006), and nurses (1.4 cm vs 3.0 cm; P =.002). Parental pre-injection anxiety was also lower (1.2 cm vs 2.9 cm; P =.016). Taking injections, including inserting catheters, was found to be less problematic with an indwelling catheter (1.6 cm vs 3.3 cm;P =.009). During the 6-month follow-up, injection pain and injection problems were significantly lower in the catheter group. Mean catheter indwelling time was 3.7 days. Median pain for catheter insertion was 2.1 cm and for glucose testing was 0.9 cm. Sixteen of 20 patients continued to use indwelling catheters after 2 weeks, and 9 of 20 after 6 months. CONCLUSIONS: We found an evident relief of pre-injection anxiety and injection pain when using indwelling catheters for introducing insulin injections at the onset of diabetes.
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| 6. |
- Stegerer, Dominik, 1988, et al.
(författare)
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Organogels from Diketopyrrolopyrrole Copolymer Ionene/Polythiophene Blends Exhibit Ground-State Single Electron Transfer in the Solid State
- 2022
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 1520-5835 .- 0024-9297. ; 55:12, s. 4979-4994
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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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| 7. |
- 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
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 11
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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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