| 1. |
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| 2. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 3. |
- Cao, Yiming, et al.
(författare)
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11% efficiency solid-state dye-sensitized solar cells with copper(II/I) hole transport materials
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Solid-state dye-sensitized solar cells currently suffer from issues such as inadequate nanopore filling, low conductivity and crystallization of hole-transport materials infiltrated in the mesoscopic TiO2 scaffolds, leading to low performances. Here we report a record 11% stable solid-state dye-sensitized solar cell under standard air mass 1.5 global using a hole-transport material composed of a blend of [Cu (4,4',6,6'-tetramethyl-2,2'-bipyridine)2(bis(trifluoromethylsulfonyl)imide)2 and [Cu (4,4',6,6'-tetramethyl-2,2'-bipyridine)2](bis(trifluoromethylsulfonyl)imide). The amorphous Cu(II/I) conductors that conduct holes by rapid hopping infiltrated in a 6.5 mm-thick mesoscopic TiO2 scaffold are crucial for achieving such high efficiency. Using time-resolved laser photolysis, we determine the time constants for electron injection from the photoexcited sensitizers Y123 into the TiO2 and regeneration of the Y123 by Cu(I) to be 25 ps and 3.2 μs, respectively. Our work will foster the development of low-cost solid-state photovoltaic based on transition metal complexes as hole conductors.
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| 4. |
- Freitag, Marina, et al.
(författare)
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Dye-sensitized solar cells for efficient power generation under ambient lighting
- 2017
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Ingår i: Nature Photonics. - : NATURE PUBLISHING GROUP. - 1749-4885 .- 1749-4893. ; 11:6, s. 372-
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Tidskriftsartikel (refereegranskat)abstract
- Solar cells that operate efficiently under indoor lighting are of great practical interest as they can serve as electric power sources for portable electronics and devices for wireless sensor networks or the Internet of Things. Here, we demonstrate a dye-sensitized solar cell (DSC) that achieves very high power-conversion efficiencies (PCEs) under ambient light conditions. Our photosystem combines two judiciously designed sensitizers, coded D35 and XY1, with the copper complex Cu(II/I)(tmby) as a redox shuttle (tmby, 4,4', 6,6'-tetramethyl-2,2'-bipyridine), and features a high open-circuit photovoltage of 1.1 V. The DSC achieves an external quantum efficiency for photocurrent generation that exceeds 90% across the whole visible domain from 400 to 650 nm, and achieves power outputs of 15.6 and 88.5 mu W cm(-2) at 200 and 1,000 lux, respectively, under illumination from a model Osram 930 warm-white fluorescent light tube. This translates into a PCE of 28.9%.
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| 5. |
- Jacobsson, T. Jesper, et al.
(författare)
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Unreacted PbI2 as a Double-Edged Sword for Enhancing the Performance of Perovskite Solar Cells
- 2016
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 138:32, s. 10331-10343
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Tidskriftsartikel (refereegranskat)abstract
- Lead halide perovskites have over the past few years attracted considerable interest as photo absorbers in PV applications with record efficiencies now reaching 22%. It has recently been found that not only the composition but also the precise stoichiometry is important for the device performance. Recent reports have, for example, demonstrated small amount of PbI2 in the perovskite films to be beneficial for the overall performance of both the standard perovskite, CH3NH3PbI3, as well as for the mixed perovskites (CH3NH3)(x)-(CH(NH2)(2))((1x))PbBryI(3y). In this work a broad range of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photo electron spectroscopy (PES), transient absorption spectroscopy (TAS), UVvis, electroluminescence (EL), photoluminescence (PL), and confocal PL mapping have been used to further understand the importance of remnant PbI2 in perovskite solar cells. Our best devices were over 18% efficient, and had in line with previous results a small amount of excess PbI2. For the PbI2-deficient samples, the photocurrent dropped, which could be attributed to accumulation of organic species at the grain boundaries, low charge carrier mobility, and decreased electron injection into the TiO2. The PbI2-deficient compositions did, however, also have advantages. The record V-oc was as high as 1.20 V and was found in PbI2-deficient samples. This was correlated with high crystal quality, longer charge carrier lifetimes, and high PL yields and was rationalized as a consequence of the dynamics of the perovskite formation. We further found the ion migration to be obstructed in the PbI2-deficient samples, which decreased the JV hysteresis and increased the photostability. PbI2-deficient synthesis conditions can thus be used to deposit perovskites with excellent crystal quality but with the downside of grain boundaries enriched in organic species, which act as a barrier toward current transport. Exploring ways to tune the synthesis conditions to give the high crystal quality obtained under PbI2-poor condition while maintaining the favorable grain boundary characteristics obtained under PbI2-rich conditions would thus be a strategy toward more efficiency devices.
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| 6. |
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| 7. |
- Rusakiewicz, Sylvie, et al.
(författare)
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NCR3/NKp30 contributes to pathogenesis in primary Sjogren's syndrome.
- 2013
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Ingår i: Science translational medicine. - : American Association for the Advancement of Science (AAAS). - 1946-6242 .- 1946-6234. ; 5:195
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Tidskriftsartikel (refereegranskat)abstract
- Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease characterized by a lymphocytic exocrinopathy. However, patients often have evidence of systemic autoimmunity, and they are at markedly increased risk for the development of non- Hodgkin's lymphoma. Similar to other autoimmune disorders, a strong interferon (IFN) signature is present among subsets of pSS patients, although the precise etiology remains uncertain. NCR3/NKp30 is a natural killer (NK)-specific activating receptor regulating the cross talk between NK and dendritic cells and type II IFN secretion. We performed a case-control study of genetic polymorphisms of the NCR3/NKp30 gene and found that rs11575837 (G>A) residing in the promoter was associated with reduced gene transcription and function as well as protection to pSS. We also demonstrated that circulating levels of NCR3/NKp30 were significantly increased among pSS patients compared with controls and correlated with higher NCR3/NKp30 but not CD16-dependent IFN-γ secretion by NK cells. Excess accumulation of NK cells in minor salivary glands correlated with the severity of the exocrinopathy. B7H6, the ligand of NKp30, was expressed by salivary epithelial cells. These findings suggest that NK cells may promote an NKp30-dependent inflammatory state in salivary glands and that blockade of the B7H6/NKp30 axis could be clinically relevant in pSS.
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| 8. |
- Saygili, Yasemin, et al.
(författare)
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Copper Bipyridyl Redox Mediators for Dye-Sensitized Solar Cells with High Photovoltage
- 2016
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 138:45, s. 15087-15096
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Tidskriftsartikel (refereegranskat)abstract
- Redox mediators play a major role determining the photocurrent and the photovoltage in dye-sensitized solar cells (DSCs). To maintain the photocurrent, the reduction of oxidized dye by the redox mediator should be significantly faster than the electron back transfer between TiO2 and the oxidized dye. The driving force for dye regeneration with the redox mediator should be sufficiently low to provide high photovoltages. With the introduction of our new copper complexes as promising redox mediators in DSCs both criteria are satisfied to enhance power conversion efficiencies. In this study, two copper bipyridyl complexes, Cu-(II/I)(dmby)(2)TFSI2/1 (0.97 V vs SHE, dmby = 6,6'-dimethyl-2,2'-bipyridine) and Cu-(II/I)(tmby)(2)TFSI2/1 (0.87 V vs SHE, tmby = 4,4',6,6'-tetramethyl-2,2'-bipyridine), are presented as new redox couples for DSCs. They are compared to previously reported Cu-(II/I)(dmp)(2)TFSI2/1 (0.93 V vs SHE, dmp = bis(2,9-dimethyl-1,10-phenanthroline). Due to the small reorganization energy between Cu(I) and Cu(II) species, these copper complexes can sufficiently regenerate the oxidized dye molecules with close to unity yield at driving force potentials as low as 0.1 V. The high photovoltages of over 1.0 V were achieved by the series of copper complex based redox mediators without compromising photocurrent densities. Despite the small driving forces for dye regeneration, fast and efficient dye regeneration (2-3 mu s) was observed for both complexes. As another advantage, the electron back transfer (recombination) rates were slower with Cu-(II/I)(tmby)(2)TFSI2/1 as evidenced by longer lifetimes. The solar-to-electrical power conversion efficiencies for [Cu(tmby)(2)](2+/1+), [Cu(dmby)(2)](2+/1+) , and [Cu(dmp)(2)](2+/1+) based electrolytes were 10.3%, 10.0%, and 10.3%, respectively, using the organic Y123 dye under 1000 W m(-2) AM1.5G illumination. The high photovoltaic performance of Cu-based redox mediators underlines the significant potential of the new redox mediators and points to a new research and development direction for DSCs.
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| 9. |
- Saygili, Yasemin, et al.
(författare)
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Liquid State and Zombie Dye Sensitized Solar Cells with Copper Bipyridine Complexes Functionalized with Alkoxy Groups
- 2020
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 124:13, s. 7071-7081
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Tidskriftsartikel (refereegranskat)abstract
- Copper redox mediators can be employed in dye sensitized solar cells (DSCs) both as liquid electrolytes or as solid state hole transport materials (HTMs). The solid state devices that employ copper complex HTMs can be simply obtained by solvent evaporation in liquid state devices. During this evolution, the copper complex molecules present in the electrolyte solvent slowly aggregate in the pores of the TiO2 film and also close the gap between the TiO2 film and counter electrode. However, the crystallization of the HTM that infiltrated in the mesoscopic TiO2 pores can lead to low photovoltaic performance. In order to prevent this problem, we designed two copper redox mediators [Cu(beto)(2)](1+) (beto = 4,4'-diethoxy-6,6'-dimethyl-2,2'-bipyridine) and [Cu(beto(2Ox))(2)](1+) (beto(2Ox) = 4,4'-bis(2-methoxyethoxy)-6,6'-dimethyl-2,2'-bipyridine) with extended side chains. First, we studied these complexes in liquid state devices in reference to the [Cu(tmby)(2)](2+/1+) complex (tmby = 4,4',6,6'-tetramethyl-2,2'-bipyridine). The solar-to- electrical power conversion efficiencies for liquid state devices were over 10% for all of the complexes by using the organic Y123 dye under 1000 Wm(-2) AM1.5G illumination. However, solid state devices showed significantly diminished charge transport properties and short circuit current density values even though the crystallization was reduced.
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| 10. |
- Thorsmolle, Verner K., et al.
(författare)
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Conduction Through Viscoelastic Phase in a Redox-Active Ionic Liquid at Reduced Temperatures
- 2012
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Ingår i: Advanced Materials. - : Wiley. - 1521-4095 .- 0935-9648. ; 24:6, s. 781-781
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Tidskriftsartikel (refereegranskat)abstract
- The phase diagram of the redox active ionic liquid 1-methyl-3-propylimidazolium iodide (PMII) is examined as a function of temperature and iodine concentration. Beyond a threshold concentration of 3.9 M, the formation of higher polyiodides gives rise to a viscoelastic phase upon cooling. Despite of the very high viscosity of such polyiodide-containing PMII melts a strikingly high conductivity is maintained through Grotthuss-type bond exchange and ionic conduction.
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