| 11. |
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| 12. |
- Gedefaw, Desta Antenehe, 1971, et al.
(författare)
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Induced photodegradation of quinoxaline based copolymers for photovoltaic applications
- 2016
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248. ; 144, s. 150-158
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Tidskriftsartikel (refereegranskat)abstract
- We report here the synthesis and characterization of a series of p-type copolymers, which combine a fluorinated quinoxaline (FQ) acceptor unit either with a differently substituted benzodithiophene (BDT) or an unsubstituted thieno[3,2-b]thiophene (TT). The effect of the structural modifications on the photochemical stability of the resulting films is investigated and then correlated with the photovoltaic performance and lifetime measurements of corresponding photovolatic devices. To this end, we firstly studied the intrinsic stability of each polymer film by monitoring the UV-vis absorption decay, under simulated sunlight, as a function of ageing time. Bulk heterojunction solar cells, based on these polymers as donor materials, were fabricated and tested. Beside the initial values, we monitored the photovoltaic performance during prolonged light soaking in order to evaluate and compare the photostability of more complex systems such as working solar cells.
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| 13. |
- Gedefaw, Desta Antenehe, 1971, et al.
(författare)
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Recent Development of Quinoxaline Based Polymers/Small Molecules for Organic Photovoltaics
- 2017
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6840 .- 1614-6832. ; 7:21
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Forskningsöversikt (refereegranskat)abstract
- Among the various molecular designs developed for the synthesis of conjugated polymers and small molecules for optoelectronic applications, the donor: acceptor (D-A) approach is the most widely explored method over the past decades. Through the covalent linkage of electron-rich and electron-deficient units, a plethora of medium-low band gap materials has been developed and tested in organic photovoltaic devices. In particular, the quinoxaline aromatic structure and its derivatives are among the most studied electron deficient aromatic units used in D-A structures. Quinoxaline based materials are endowed with characteristics that are useful for large scale production in real world applications, such as easy synthetic procedures and excellent stability in air. Moreover, the use of quinoxaline based polymers/small molecules in bulk heterojunction (BHJ) devices led to power conversion efficiencies over 9%. Considering the potential of quinoxaline based materials, this review gathers together quinoxaline based polymers and small molecules reported in the literature during the last 5 years, summarizing and discussing the structure-properties relationships for this class of organic semiconductors, aiming to serve as a background and to promote efforts for the further development of new quinoxaline derivatives with improved and advanced properties for future applications.
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| 14. |
- Gedefaw, Desta Antenehe, 1971, et al.
(författare)
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Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications
- 2016
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Ingår i: Beilstein Journal of Organic Chemistry. - : Beilstein Institut. - 1860-5397. ; 12, s. 1629-1637
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Tidskriftsartikel (refereegranskat)abstract
- Two high bandgap benzodithiophene-benzotriazole-based polymers were synthesized via palladium-catalysed Stille coupling reaction. In order to compare the effect of the side chains on the opto-electronic and photovoltaic properties of the resulting polymers, the benzodithiophene monomers were substituted with either octylthienyl (PTzBDT-1) or dihexylthienyl (PTzBDT-2) as side groups, while the benzotriazole unit was maintained unaltered. The optical characterization, both in solution and thin-film, indicated that PTzBDT-1 has a red-shifted optical absorption compared to PTzBDT-2, likely due to a more planar conformation of the polymer backbone promoted by the lower content of alkyl side chains. The different aggregation in the solid state also affects the energetic properties of the polymers, resulting in a lower highest occupied molecular orbital (HOMO) for PTzBDT-1 with respect to PTzBDT-2. However, an unexpected behaviour is observed when the two polymers are used as a donor material, in combination with PC61BM as acceptor, in bulk heterojunction solar cells. Even though PTzBDT-1 showed favourable optical and electrochemical properties, the devices based on this polymer present a power conversion efficiency of 3.3%, considerably lower than the efficiency of 4.7% obtained for the analogous solar cells based on PTzBDT-2. The lower performance is presumably attributed to the limited solubility of the PTzBDT-1 in organic solvents resulting in enhanced aggregation and poor intermixing with the acceptor material in the active layer.
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| 15. |
- Kadesjo, E, et al.
(författare)
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Acute versus chronic myocardial injury and long-term outcomes
- 2019
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Ingår i: Heart (British Cardiac Society). - : BMJ. - 1468-201X .- 1355-6037. ; 105:24, s. 1905-1912
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Tidskriftsartikel (refereegranskat)abstract
- There is a paucity of data regarding prognosis in patients with acute versus chronic myocardial injury for long-term outcomes. We hypothesised that patients with chronic myocardial injury have a similar long-term prognosis as patients with acute myocardial injury.MethodsIn an observational cohort study of 22 589 patients who had high-sensitivity cardiac troponin T (hs-cTnT) measured in the emergency department during 2011–2014, we identified all patients with level >14 ng/L and categorised them as acute myocardial injury, type 1 myocardial infarction (T1MI), type 2 myocardial infarction (T2MI) or chronic myocardial injury through adjudication. We estimated adjusted HRs with 95% CIs for the primary outcome all-cause mortality and secondary outcomes MI, and heart failure in patients with acute myocardial injury, T1MI and T2MI compared with chronic myocardial injury.ResultsIn total, 3853 patients were included. During 3.9 (±2) years of follow-up, 48%, 24%, 44% and 49% of patients with acute myocardial injury, T1MI, T2MI and chronic myocardial injury died, respectively. Patients with acute myocardial injury had higher adjusted risks of death (1.21, 95% CI 1.08 to 1.36) and heart failure (1.24, 95% CI 1.07 to 1.43), but a similar risk for myocardial infarction (MI) compared with the reference group. Patients with T1MI had a lower adjusted risk of death (0.86, 95% CI 0.74 to 1.00) and higher risk of MI (2.09, 95% CI 1.62 to 2.68), but a similar risk of heart failure. Patients with T2MI had a higher adjusted risk of death (1.46, 95% CI 1.18 to 1.80) and heart failure (1.30, 95% CI 1.00 to 1.69) compared with patients with chronic myocardial injury.ConclusionsAbsolute long-term risks for death are similar, and adjusted risks are slightly higher, among patients with acute myocardial injury and T2MI, respectively, compared with chronic myocardial injury. The lowest risk of long-term mortality was found in patients with T1MI. Both acute and chronic myocardial injury are associated with very high risks of adverse outcomes.
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| 16. |
- Mohammad, M. A., et al.
(författare)
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Intravenous beta-blocker therapy in ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention is not associated with benefit regarding short-term mortality: a Swedish nationwide observational study
- 2017
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Ingår i: Eurointervention. - : Europa Digital & Publishing. - 1774-024X .- 1969-6213. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Our aim was to investigate the impact of intravenous (IV) beta-blocker therapy on short-term mortality and other in-hospital events in patients with ST-segment elevation myocardial infarction (STEMI) treated with dual antiplatelet therapy (DAPT) and primary percutaneous coronary intervention (PCI). Methods and results: Using the nationwide Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies (SWEDEHEART) registry, we identified all patients with STEMI undergoing PCI between 2006 and 2013. Patients with cardiogenic shock and cardiac arrest at presentation were excluded. The primary endpoint was mortality within 30 days. Secondary endpoints were in-hospital events (mortality, cardiogenic shock and left ventricular ejection fraction [LVEF] <40% at discharge). We adjusted for confounders with a multivariable model and propensity score matching. Out of 16,909 patients, 2,876 (17.0%) were treated with an IV beta-blocker. After adjusting for confounders, the IV beta-blocker group had higher 30-day all-cause mortality (HR: 1.44, 95% CI: 1.14-1.83), more in-hospital cardiogenic shock (OR: 1.53, 95% CI: 1.09-2.16) and were more often discharged with an LVEF <40% (OR: 1.70, 95% CI: 1.51-1.92). Conclusions: In this large nationwide observational study, the use of IV beta-blockers in patients with STEMI treated with primary PCI was associated with higher short-term mortality, lower LVEF at discharge, as well as a higher risk of in-hospital cardiogenic shock.
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| 17. |
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| 18. |
- Pan, Xun, et al.
(författare)
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Environmentally friendly preparation of nanoparticles for organic photovoltaics
- 2018
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Ingår i: Organic Electronics: physics, materials, applications. - : Elsevier BV. - 1566-1199. ; 59, s. 432-440
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous nanoparticle dispersions were prepared from a conjugated polymer poly[thiophene-2,5-diyl-alt-5,10-bis((2-hexyldecyl)oxy)dithieno[3,2-c:3′,2′-h][1,5]naphthyridine-2,7-diyl] (PTNT) and fullerene blend utilizing chloroform as well as a non-chlorinated and environmentally benign solvent, o-xylene, as the miniemulsion dispersed phase solvent. The nanoparticles (NPs) in the solid-state film were found to coalesce and offered a smooth surface topography upon thermal annealing. Organic photovoltaics (OPVs) with photoactive layer processed from the nanoparticle dispersions prepared using chloroform as the miniemulsion dispersed phase solvent were found to have a power conversion efficiency (PCE) of 1.04%, which increased to 1.65% for devices utilizing NPs prepared from o-xylene. Physical, thermal and optical properties of NPs prepared using both chloroform and o-xylene were systematically studied using dynamic mechanical thermal analysis (DMTA) and photoluminescence (PL) spectroscopy and correlated to their photovoltaic properties. The PL results indicate different morphology of NPs in the solid state were achieved by varying miniemulsion dispersed phase solvent.
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| 19. |
- Seri, Mirko, et al.
(författare)
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A New Quinoxaline and Isoindigo Based Polymer as Donor Material for Solar Cells: Role of Ecofriendly Processing Solvents on the Device Efficiency and Stability
- 2017
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Ingår i: Journal of Polymer Science, Part A: Polymer Chemistry. - : Wiley. - 1099-0518 .- 0887-624X. ; 55:2, s. 234-242
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Tidskriftsartikel (refereegranskat)abstract
- A new semiconducting polymer based on two different electron deficient (quinoxaline and isoindigo) and electron rich (benzodithiophene) moieties is synthesized, characterized and used as donor material for photovoltaic devices. Blade-coated bulk heterojunction solar cells are fabricated in air by using chlorinated (o-dichlorobenzene) and nonchlorinated (o-xylene) solvents for the deposition of the active layer. The use of o-xylene allows a similar to 10% improvement of the device efficiency in comparison to the analogous system processed from o-dichlorobenzene. In addition, the evolution of the photovoltaic parameters of the resulting devices during thermal stress is monitored and compared, demonstrating a nearly identical resistance against temperature. The reported results not only highlight the promising properties of the new polymer in terms of environmental stability and compatibility with nonhalogenated solvents, but also show an easy and ecofriendly way to further improve the device performance without altering the corresponding thermal stability.
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| 20. |
- Sharma, Anirudh, et al.
(författare)
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Probing the Relationship between Molecular Structures, Thermal Transitions, and Morphology in Polymer Semiconductors Using a Woven Glass-Mesh-Based DMTA Technique
- 2019
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 31:17, s. 6740-6749
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Tidskriftsartikel (refereegranskat)abstract
- The glass transition temperature (T-g) of polymers is an important parameter that determines the kinetics of molecular organization of polymeric chains. Understanding the T-g of conjugated polymers is critical in achieving a thermally stable and optimum morphology in polymer:polymer or polymer:small molecule blends in organic electronics. In this study, we have used the woven glass-mesh-based method of dynamic mechanical thermal analysis (DMTA) to evaluate the T-g of polymer semiconductors, which is generally not easy to detect using conventional techniques such as differential scanning calorimetry (DSC). More importantly, we establish the relationship between the thermal transitions and the molecular structure of polymer semiconductors. For conjugated polymers with rigid conjugated backbones and large alkyl side chains, we report the presence of separate thermal transitions corresponding to the polymer backbone as well as transitions related to side chains, with the latter being the most prominent. By systematically comparing polymer side chains, molecular weight, and backbone structure, the origin of the T-g and a sub-T-g transitions have been successfully correlated to the polymer structures. The antiplastization effect of additives has also been used to further prove the origin of the different transitions. Thermal transitions of a range of high performing polymers applied in organic photovoltaics, including TQ1, PTNT, PTB7, PTB7-Th, and N2200, have been systematically studied in this work. According to the measurements, some of these polymers have a very small amorphous part, changing the way the morphology should be described for these materials. We infer that the main phase in these polymers consists of hairy aggregates, with a few pi-stacked rigid polymer chains forming the aggregates.
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