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  • 1. Benatto, Leandro
    et al.
    Marchiori, Cleber
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Araujo, Carlos Moyses
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Koehler, Marlus
    Molecular origin of efficient hole transfer from non-fullerene acceptors: insights from first-principles calculations2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 39, p. 12180-12193Article in journal (Refereed)
    Abstract [en]

    Due to the strong exciton binding energy (E-b) of organic materials, the energy offset between donor (D) and acceptor (A) materials is essential to promote charge generation in organic solar cells (OSCs). Yet an efficient exciton dissociation from non-fullerene acceptors (NFAs) began to be observed in D/A blends even at very low driving force for hole transfer (Delta H-h). The mechanism behind this efficient photoinduced hole transfer (PHT) remains unclear since current estimates from calculations of isolated molecules indicate that E-b > Delta H-h. Here we rationalize these discrepancies using density functional theory (DFT), the total Gibbs free energy method and the extended Huckel theory (EHT). First, we employed DFT to calculate E-b for NFAs of three representative groups (perylene diimide derivatives, indacenodithiophene and subphthalocyanines) as well as for fullerene acceptors (FAs). Considering isolated molecules in the calculations, we verified that E-b for NFAs is lower than for FAs but still higher than the experimental Delta H-h in which efficient PHT has been observed. Finding the molecular geometry of the excited state, we also obtain that the structural relaxation after photoexcitation tends to further decrease (increase) E-b for NFAs (FAs). This effect helps explain the delayed charge generation measured in some NFA systems. However, this effect is still not large enough for a significant decrease in E-b. We then applied EHT to quantify the decrease of E-b induced by energy levels coupling between stacked molecules in a model aggregate. We then estimated the number of stacked molecules so that E-b approaches Delta H-h's. We found that small NFA aggregates, involving around 5 molecules, are already large enough to explain the experiments. Our results are justified by the low energy barrier to the generation of delocalized states in these systems (especially for the hole delocalization). Therefore, they indicate that molecular systems with certain characteristics can achieve efficient molecular orbital delocalization, which is a key factor to allow an efficient exciton dissociation in low-driving-force systems. These theoretical findings provide a sound explanation to very recent observations in OSCs.

  • 2.
    Benesperi, Iacopo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala Univ, Dept Chem, Angstrom Lab, S-75120 Uppsala, Sweden.
    Michaels, Hannes
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Freitag, Marina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    The researcher's guide to solid-state dye-sensitized solar cells2018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 44, p. 11903-11942Article, review/survey (Refereed)
    Abstract [en]

    In order to sustainably support its ever-increasing energy demand, the human society will have to harvest renewable energy wherever and whenever possible. When converting light to electricity, silicon solar cells are the technology of choice to harvest direct sunlight due to their high performance and continuously dropping price. For diffused light and indoor applications, however, silicon is not the material of choice. To power the next gizmo in your smart home, dye-sensitized solar cells (DSCs) are a viable alternative. Made from inexpensive, earth-abundant, and non-toxic materials, DSCs perform best at low light intensity. So far, issues such as leakage of the liquid electrolyte and its corrosive nature have limited the commercialization of this technology. To overcome these limitations, solid-state DSCs (ssDSCs) - in which the liquid electrolyte is replaced by a solid material - have been developed. For many years their efficiencies have been poor, preventing them from being widely employed. In the past six years, however, research efforts have led them to rival with their liquid counterparts. Here, we will review recent advancements in the field of ssDSCs. Every device component will be acknowledged, from metal oxides and new dyes to novel hole transporters, dopants, counter-electrodes and device architectures. After reviewing materials, long-term stability of devices will be addressed, finally giving an insight into the future that awaits this exciting technology.

  • 3.
    Irkhina, A.
    et al.
    Helmholtz Zentrum Berlin Mat & Energie, Dept Struct & Dynam Energy Mat, D-14109 Berlin, Germany.
    Levcenko, S.
    Helmholtz Zentrum Berlin Mat & Energie, Dept Struct & Dynam Energy Mat, D-14109 Berlin, Germany.
    Xie, Ling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Unold, T.
    Helmholtz Zentrum Berlin Mat & Energie, Dept Struct & Dynam Energy Mat, D-14109 Berlin, Germany.
    Radiative emission from Cu2ZnSnS4/ZnSn core/shell nanocrystals2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 20, p. 6129-6133Article in journal (Refereed)
    Abstract [en]

    Kesterite Cu2ZnSnS4 (CZTS) nanocrystals so far have been found to luminesce neither at room temperature nor at low temperature. Here a core-shell architecture for kesterite CZTS nanocrystals is demonstrated by applying a ZnSn-alloy shell overcoating approach. These CZTS/ZnSn nanocrystals show luminescence emission at 1.05 eV, which is red-shifted by about 0.4 eV from the absorption onset and is attributed to a radiative transition involving a deep defect. Temperature-dependent photoluminescence measurements within a range of 20-200 K indicate the presence of a competing nonradiative channel with an activation energy of 50-60 meV.

  • 4.
    Jane, R. T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Gaudemer, E.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lomoth, Reiner
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Surface modification of carbon and metal electrodes with bistable molecular redox switches by click and amide coupling2015In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 38, p. 10023-10030Article in journal (Refereed)
    Abstract [en]

    Ruthenium complexes [Ru(R-Ph-tpy)(bpyMeOHpy)] (Ph-tpy = 4'-(4-R-phenyl)-2,2':6',2 ''-terpyridine, R = NH2, COOH, CRCH, bpyMeOHpy = 1-[6-(2,2'-bipyridyl)]-1-(2-pyridyl)-ethanol) were covalently attached to carbon and metal electrodes by amide and click coupling reactions. Coupling agents were covalently grafted onto the electrodes by electrochemical reduction of p-functionalized diazonium tethers X-Ph-N-2(+) (X = COOH, NO2, N-3) followed by electrochemical reduction of the nitro tether. The modification of the electrode surfaces with the Ru complexes results in a hysteretic current-voltage response based on the redox-induced N-6/N5O linkage isomerism of the ambidentate pyridyl/alkoxy unit in the bpyMeOHpy chelate ligand. The immobilized complexes can be exhaustively addressed electrochemically with scan rates <= 10000 V s(-1) and can switch uniformly with kinetic and thermodynamic parameters similar to the properties of reference complexes in homogeneous solution.

  • 5.
    Jane, Reuben T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Lomoth, Reiner
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Redox hysteresis on carbon electrodes covalently modified with a bistable ruthenium complex2015In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 24, p. 6260-6265Article in journal (Refereed)
    Abstract [en]

    A ruthenium complex bearing an ambidentate ligand was covalently attached to glassy carbon and carbon fiber electrodes by reduction of an aryldiazonium anchoring group placed on the terpyridine spectator ligand. The diazonium grafting method results in robust attachment and yields high surface concentrations of 2.4 x 10(-10) mol cm(-2). The attached complexes can be addressed electrochemically and the electrodes were characterized with scan rates of up to 2000 V s(-1). The redox-induced N/O linkage isomerism of the pyridyl/alkoxy ambidentate ligand results in a hysteretic current-voltage response (E-1 degrees = 0.83, E-2 degrees = 0.34 V) of the modified electrodes. The immobilization has no deleterious effects on the isomerization reactions of the molecular material that proceed with thermodynamic (2.4 < pK(1) < 3.7 (Ru(III) O -> N), -6.0 < pK(2) < -4.8 (Ru(II) O -> N)) and kinetic parameters (k(b1) = 2.5 x 10(2) s(-1) (Ru(III) N -> O), k(f2) = 2.5 x 10(2) s(-1) (Ru(II) O -> N)) comparable to analogous complexes in homogeneous solution.

  • 6.
    Jesus Luque, Francisco
    et al.
    Univ Autonoma Madrid, Dept Fis Materia Condensada, E-28049 Madrid, Spain.
    Kowalik, Iwona Agnieszka
    Polish Acad Sci, Inst Phys, PL-02668 Warsaw, Poland.
    Pablo Prieto-Ruiz, Juan
    Univ Valencia, Inst Ciencia Mol ICMol, Paterna 46980, Spain.
    Angel Nino, Miguel
    IMDEA Nanosci, Madrid 28049, Spain.
    Prima-Garcia, Helena
    Univ Valencia, Inst Ciencia Mol ICMol, Paterna 46980, Spain.
    Manuel Romero, Francisco
    Univ Valencia, Inst Ciencia Mol ICMol, Paterna 46980, Spain.
    Arvanitis, Dimitri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Coronado, Eugenio
    Univ Valencia, Inst Ciencia Mol ICMol, Paterna 46980, Spain.
    Miranda, Rodolfo
    Univ Autonoma Madrid, Condensed Matter Phys Ctr IFIMAC, E-28049 Madrid, Spain;IMDEA Nanosci, Madrid 28049, Spain;Univ Autonoma Madrid, Dept Fis Materia Condensada, E-28049 Madrid, Spain.
    Jose de Miguel, Juan
    Univ Autonoma Madrid, Condensed Matter Phys Ctr IFIMAC, E-28049 Madrid, Spain;Univ Autonoma Madrid, Dept Fis Materia Condensada, E-28049 Madrid, Spain;Univ Autonoma Madrid, Inst Fis Mat Nicolas Cabrera, E-28049 Madrid, Spain.
    Magnetic ordering in an (Fe0.2Cr0.8)(1.5)[Cr(CN)(6)] Prussian blue analogue studied with synchrotron radiation based spectroscopies2018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 30, p. 8171-8186Article in journal (Refereed)
    Abstract [en]

    The appearance of magnetic order in the (Fe0.2Cr0.8)(1.5)[Cr(CN)(6)]center dot 15H(2)O Prussian blue analogue at low temperature has been investigated by means of synchrotron radiation-based X-ray absorption spectroscopy and X-ray magnetic circular dichroism. With the help of ligand field multiplet analysis we have been able to identify the oxidation states of the metallic cations present in the sample and their evolution with temperature. Our experiments reveal that the appearance of ferromagnetic order is triggered by the transformation of Cr-III cations to Cr-II high-spin caused by a transfer of electrons from the Fe to the Cr resulting in an increase of the magnetic interactions within the (Cr, Cr) sublattice. The misfit strain between the (Fe, Cr) and the (Cr, Cr) moieties that coexist within this ternary material influences the balance of oxidation states and hence the magnetic properties of the metallic ions. Misfit relaxation also plays a role in determining the differences between the surface and the bulk of the material. The measurement of the magnetic moments in those two regions suggests that the surface may have a reduced Curie temperature compared to the bulk.

  • 7.
    Jesus Luque, Francisco
    et al.
    Univ Autonoma Madrid, Dept Fis Mat Condensada, Cantoblanco, E-28049 Madrid, Spain.
    Kowalik, Iwona Agnieszka
    Polish Acad Sci, Inst Phys, PL-02668 Warsaw, Poland.
    Pablo Prieto-Ruiz, Juan
    Univ Valencia, Inst Ciencia Mol ICMol, Paterna 46980, Spain.
    Angel Nino, Miguel
    IMDEA Nanosci, Cantoblanco, Madrid 28049, Spain.
    Prima-Garcia, Helena
    Univ Valencia, Inst Ciencia Mol ICMol, Paterna 46980, Spain.
    Manuel Romero, Francisco
    Univ Valencia, Inst Ciencia Mol ICMol, Paterna 46980, Spain.
    Arvanitis, Dimitri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Mathoniere, Corine
    CNRS, ICMCB, UMR 5026, F-33800 Pessac, France;Univ Bordeaux, ICMCB, UMR 5026, F-33700 Pessac, France.
    Coronado, Eugenio
    Univ Valencia, Inst Ciencia Mol ICMol, Paterna 46980, Spain.
    Miranda, Rodolfo
    Univ Autonoma Madrid, Dept Fis Mat Condensada, Cantoblanco, E-28049 Madrid, Spain;IMDEA Nanosci, Cantoblanco, Madrid 28049, Spain;Univ Autonoma Madrid, Condensed Matter Phys Ctr IFIMAC, Cantoblanco, E-28049 Madrid, Spain.
    Jose de Miguel, Juan
    Univ Autonoma Madrid, Dept Fis Mat Condensada, Cantoblanco, E-28049 Madrid, Spain;Univ Autonoma Madrid, Condensed Matter Phys Ctr IFIMAC, Cantoblanco, E-28049 Madrid, Spain;Univ Autonoma Madrid, Inst Fis Mat Nicolas Cabrera, Cantoblanco, E-28049 Madrid, Spain.
    Photoinduced effects on the magnetic properties of the ( Fe0.2Cr0.8) 1.5[ Cr( CN) 6] Prussian blue analogue2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 8, p. 2305-2317Article in journal (Refereed)
    Abstract [en]

    One of the most attractive characteristics of some Prussian blue derivatives is the sensitivity of their magnetic properties to the irradiation with light. In this work photoinduced effects in the (Fe0.2Cr0.8)(1.5)[Cr(CN)(6)]15H(2)O PBA have been studied by means of X-ray-based spectroscopies and magnetometry. It is found that the photosensitivity of this compound is mostly centred on the Fe cations: the exposure to green light induces a transfer of electrons from them to the Cr that provokes a reversal of the previously existing linkage isomerization and increases the elastic strain caused by the misfit of the unit cells of the Fe-NC-Cr and Cr-NC-Cr sublattices. The green light also quenches the magnetism of the Fe-II high-spin (HS) ions present in the sample and reduces the magnetic moments of most of the Cr cations except for Cr-II HS. Our study highlights the important role played by the mismatch between the unit cells of the coexisting sub-lattices in ternary Prussian blue analogues.

  • 8.
    Kowalik, Iwona Agnieszka
    et al.
    Polish Acad Sci, Inst Phys, Al Lotnikow 32-46, PL-02668 Warsaw, Poland.
    Szwacki, Nevill Gonzalez
    Univ Warsaw, Fac Phys, Inst Theoret Phys, PL-00681 Warsaw, Poland.
    Angel Nino, Miguel
    IMDEA Nanociencia, Campus Cantoblanco, E-28049 Madrid, Spain.
    Jesus Luque, Francisco
    Univ Autonoma Madrid, Dept Fis Mat Condensada, E-28049 Madrid, Spain.
    Arvanitis, Dimitri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Stable antiferromagnetic nanocrystals for room temperature applications: the case of iron nitride2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 31, p. 9474-9480Article in journal (Refereed)
    Abstract [en]

    We characterise the magnetism of self-assembled FenN nanocrystals, combining core level spectroscopy with first-principles theory. Not only ferromagnetic but also antiferromagnetic iron nitride nanocrystals are identified, exhibiting stable magnetic properties at room temperature. New stable magnetic phases are found, previously believed to order magnetically only well below room temperature. As determined by the growth conditions, several phases of magnetic FenN nanocrystals are identified in the near surface region of GaN based thin films, with typical dimensions from 50 to 100 nm, embedded in the (Ga,Fe)N lattice or residing on the GaN surface. We determine, at room temperature, Fe4N and Fe3N ferromagnetic nanocrystals, as well as Fe2N and FeN nanocrystals in an antiferromagnetic state, which is not stable at room temperature in their bulk phases.

  • 9.
    Kumar, Ankit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India.
    Jana, Somnath
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sharma, S. K.
    Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA..
    Chaudhary, S.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Pandya, D. K.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Anti-phase boundary free two-dimensional epitaxial Fe3O4 thin films: evidence of an unquenched orbital magnetic moment at room temperature2016In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 42, p. 9942-9946Article in journal (Refereed)
    Abstract [en]

    Two-dimensional (2-D) epitaxial ferrimagnetic Fe3O4 thin films are attractive choices for the next generation of spin devices due to their half-metallicity, high Curie temperature and high electrical conductivity. Despite having profound spin device compatibility, the use of Fe3O4 thin films has not been exploited to date due to the presence of a magnetic disorder known as anti-phase boundaries (APBs). Here we demonstrate the growth of 2D single crystalline APB free Fe3O4(100) thin films on TiN buffered Si(100). The epitaxial orientation relationship, Si(400)// TiN(200)// Fe3O4(400), was confirmed by reflection high-energy electron diffraction and polarized Raman analysis. The Fe3O4(100) thin films possess large in-plane magnetic domains in its remanent magnetization state and cubic in-plane magnetic anisotropy as confirmed using magnetic force microscopy and magneto-optic Kerr effect measurements, respectively. The orbital to spin angular moment ratio, m(l)/m(s) = 0.144, and the total magnetic moment extracted from X-ray magnetism circular dichroism (XMCD) measurements are close to the corresponding bulk value.

  • 10.
    Liu, Peng-Fei
    et al.
    Beijing Computat Sci Res Ctr, Beijing 100094, Peoples R China;Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China;Dongguan Neutron Sci Ctr, Dongguan 523803, Peoples R China;Shanxi Univ, Collaborat Innovat Ctr Extreme Opt, Taiyuan 030006, Shanxi, Peoples R China.
    Bo, Tao
    Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China;Dongguan Neutron Sci Ctr, Dongguan 523803, Peoples R China.
    Liu, Zhifeng
    Beijing Computat Sci Res Ctr, Beijing 100094, Peoples R China;Inner Mongolia Univ, Sch Phys Sci & Technol, Hohhot 010021, Peoples R China.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Wang, Fangwei
    Dongguan Neutron Sci Ctr, Dongguan 523803, Peoples R China;Chinese Acad Sci, Inst Phys, Beijing Natl Lab Condensed Matter Phys, Beijing 100080, Peoples R China.
    Zhao, Jijun
    Beijing Computat Sci Res Ctr, Beijing 100094, Peoples R China;Dalian Univ Technol, Minist Educ, Key Lab Mat Modificat Laser Ion & Electron Beams, Dalian 116024, Peoples R China.
    Wang, Bao-Tian
    Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China;Dongguan Neutron Sci Ctr, Dongguan 523803, Peoples R China;Shanxi Univ, Collaborat Innovat Ctr Extreme Opt, Taiyuan 030006, Shanxi, Peoples R China.
    Hexagonal M2C3 (M = As, Sb, and Bi) monolayers: new functional materials with desirable band gaps and ultrahigh carrier mobility2018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 46, p. 12689-12697Article in journal (Refereed)
    Abstract [en]

    Based on first-principles calculations, we propose a new type of two-dimensional (2D) material M2C3 (M = As, Sb, and Bi) showing an infinite hexagonal lattice, in which C atoms adopt sp(2) hybridization and M atoms prefer three-fold coordination with lone pair electrons. Such monolayers are calculated to be stable verified by their moderate cohesive energies, the absence of imaginary modes in their phonon spectra, and the high melting points predicted via molecular dynamics simulations. Sb2C3 and Bi2C3 monolayers possess intrinsic band gaps of 1.58 and 1.23 eV (based on HSE06 calculations), values suitable for photovoltaic applications. The intrinsic acoustic-phonon-limited carrier mobility of the As2C3 sheet can reach up to 4.45 x 10(5) cm(2) V-1 s(-1) for electrons at room temperature, higher than that of (60-200 cm(2) V-1 s(-1)) MoS2 and (approximate to 10(3) cm(2) V-1 s(-1)) few-layer phosphorene, approaching the figure of merit in graphene (3 x 10(5) cm(2) V-1 s(-1)). The well-located band edge and visible light absorption make stretched Sb2C3 a potentially promising optoelectronic material for photocatalytic water splitting. Besides, Sb2C3/As2C3 excitonic solar cells have been proposed, and their power conversion efficiencies are estimated to exceed 23%. First-principles calculations have demonstrated that Sb2C3/Bi2C3 heterojunctions are indeed 2D node-line semimetals in the absence of spin-orbit coupling.

  • 11.
    Marin, Riccardo
    et al.
    Univ Ottawa, Dept Chem & Biomol Sci, 10 Marie Curie, Ottawa, ON K1N 6N5, Canada.
    Oussta, Fadi
    Univ Ottawa, Dept Chem & Biomol Sci, 10 Marie Curie, Ottawa, ON K1N 6N5, Canada.
    Katea, Sarmad Naim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Prabhudev, Sagar
    McMaster Univ, Dept Mat Sci & Engn, 1280 Main St West, Hamilton, ON L8S 4M1, Canada;McMaster Univ, Canadian Ctr Electron Microscopy, 1280 Main St West, Hamilton, ON L8S 4M1, Canada.
    Botton, Gianluigi A.
    McMaster Univ, Dept Mat Sci & Engn, 1280 Main St West, Hamilton, ON L8S 4M1, Canada;McMaster Univ, Canadian Ctr Electron Microscopy, 1280 Main St West, Hamilton, ON L8S 4M1, Canada.
    Westin, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hemmer, Eva
    Univ Ottawa, Dept Chem & Biomol Sci, 10 Marie Curie, Ottawa, ON K1N 6N5, Canada.
    Europium-doped ZnO nanosponges: controlling optical properties and photocatalytic activity2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 13, p. 3909-3919Article in journal (Refereed)
    Abstract [en]

    The optical features and photocatalytic activity of porous undoped and Eu3+-doped zinc oxide (ZnO) sponge-like structures, annealed at various temperatures, were assessed to establish the relationship between structure, morphology and photophysical properties. Upon monitoring the degradation of organic dye rhodamine B, undoped ZnO nanosponges annealed at 800 °C showed the highest photocatalytic activity, being among the best performing ZnO-based photocatalysts reported so far. The observed red- and blue-shift of the characteristic broad-band ZnO emission spectra as a function of the annealing temperature was ascribed to the nature of defects induced into the ZnO structure related to deficiency or excess of oxygen at lower (200 to 400 °C) and higher (500 to 1000 °C) annealing temperatures. These temperature-induced defects - along with the morphological sample characteristics - governed the photocatalytic performance. Doping-induced enhancement of the photocatalytic activity was noticed in specific samples and was found to markedly depend on the intrinsic properties of the undoped material. Overall, annealing temperature and europium doping concentration synergistically contributed to the defect structure, morphology and crystallinity, ultimately determining optical properties and therewith correlated photocatalytic activity.

  • 12.
    Mindemark, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Umea Univ, Dept Phys, Organ Photon & Elect Grp, SE-90187 Umea, Sweden..
    Edman, L.
    Umea Univ, Dept Phys, Organ Photon & Elect Grp, SE-90187 Umea, Sweden..
    Illuminating the electrolyte in light-emitting electrochemical cells2016In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 3, p. 420-432Article, review/survey (Refereed)
    Abstract [en]

    Light-emitting electrochemical cells (LECs) convert electric current to light within an active material comprising an electroluminescent organic semiconductor and an electrolyte. It is well established that it is the presence of this electrolyte that enabled the recent development of low-cost fabrication methods of functional LECs as well as the realisation of unique device architectures. At the same time, it should be acknowledged that the current lower performance of LECs in comparison to the more commonplace organic light-emitting diode, at least in part, is intimately linked to the utilisation of non-ideal electrolytes. In this review, we present the tasks that the electrolyte should fulfil during the various stages of LEC operation, and how the characteristics of the electrolyte can affect the LEC performance, specifically the turn-on time, the efficiency and the operational stability. We thereafter introduce the different classes of electrolytes that have been implemented in LEC devices up to date, and discuss how these electrolytes have been able to meet the specific requirements of the LEC technology.

  • 13.
    Poonia, Ekta
    et al.
    DCR Univ Sci & Technol, Dept Chem, Phys Chem Res Lab, Murthal 131039, Haryana, India.
    Mishra, Prashant Kumar
    Ctr Fire Explos & Environm Safety, Environm Safety Grp, Delhi 110054, India;Univ Delhi, Dept Chem, Delhi 110007, India.
    Kiran, Vijay
    CRA Coll Sonipat, Dept Chem, Sonipat 131001, Haryana, India.
    Sangwan, Jasbir
    GSSS Tajpur, Dept Sch Educ, Sonipat 131027, Haryana, India.
    Kumar, Rakesh
    Univ Delhi, Dept Chem, Delhi 110007, India.
    Rai, Pramod Kumar
    Ctr Fire Explos & Environm Safety, Environm Safety Grp, Delhi 110054, India.
    Malik, Ritu
    Univ Calif Berkeley, BSAC, Berkeley, CA 94720 USA.
    Tomer, Vijay K.
    Univ Calif Berkeley, BSAC, Berkeley, CA 94720 USA.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Mishr, Yogendra Kumar
    Univ Kiel, Inst Mat Sci, Funct Nanomat Chair, Kaiserstr 2, D-24143 Kiel, Germany.
    Aero-gel based CeO2 nanoparticles: synthesis, structural properties and detailed humidity sensing response2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 18, p. 5477-5487Article in journal (Refereed)
    Abstract [en]

    In this work, we present aero-gel based cerium oxide (CeO2) nanoparticles for the relative humidity (%RH) sensing application. X-ray diffraction (XRD) and N-2 adsorption-desorption isotherms revealed that the synthesized CeO2 nanoparticles (NPs) possessed a face centered cubic (fcc) structure with a high surface area (268 m(2) g(-1)). The high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and selected area electron diffraction (SAED) studies confirmed that the shape of CeO2 NPs was spherical and they possessed a polycrystalline nature. X-ray photoelectron spectroscopy (XPS) studies revealed the presence of both trivalent (Ce3+) and tetravalent (Ce4+) oxidation states of ceria. The CeO2 NPs' response towards %RH was explored by measuring the important sensing attributes (response/recovery, linearity, hysteresis, repeatability and stability) at 11-98%RH and at room temperature. An impressive impedance change of 4.5 orders of magnitude was observed along with a swift response (4.6 s) time and rapid recovery (2.7 s) time. Moreover, the prepared sensor showed negligible hysteresis, excellent stability and good reversible response in the complete 11-98%RH range.

  • 14.
    Silvearv, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Larsson, Peter
    Jones, Sarah. L. T.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Larsson, J. Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Establishing the most favorable metal-carbon bond strength for carbon nanotube catalysts2015In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 14, p. 3422-3427Article in journal (Refereed)
    Abstract [en]

    We have studied a wide range of transition metals to find potential carbon nanotube (CNT) catalysts for chemical vapor deposition (CVD) production. The adhesion strengths between a CNT and a metal cluster were calculated using first principle density functional theory (DFT) for all 1st, 2nd and 3rd row transition metals. We have developed the criterion that the metal-carbon adhesion strength per bond must fulfill a Goldilocks principle for catalyzing CNT growth and used it to identify, besides the well known catalysts Fe, Co and Ni, a number of other potential catalysts, namely Y, Zr, Rh, Pd, La, Ce and Pt. Our results are consistent with previous experiments performed either in a carbon arc discharge environment or by a CVD-process with regard to CNT catalyst activity.

  • 15. Whittle, Thomas A.
    et al.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Withers, Ray L.
    Liu, Yun
    Howard, Christopher J.
    Schmid, Siegbert
    Novel insight into the structure and properties of lead-free dielectric Sr3TiNb4O152018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 33, p. 8890-8896Article in journal (Refereed)
    Abstract [en]

    Sr3TiNb4O15 has been synthesised and its structure and dielectric properties characterised. In contrast to previously reported results the compound has been found to form with Pna21 symmetry and unit cell dimensions a = 12.3631(19), b = 12.4027(19) and c = 7.7601(12) Å. Variable temperature studies show a phase transition from orthorhombic to tetragonal symmetry at approximately 625 K, much higher than previously reported. Temperature-dependent dielectric measurements have also been performed and these correlate very well with the observed phase transition temperature.

  • 16.
    Yang, Xiaoyong
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Southwest Univ Sci & Technol, Natl Collaborat Innovat Ctr Nucl Waste & Environm, Mianyang 621010, Sichuan, Peoples R China.
    Singh, Deobrat
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Xu, Zhitong
    Southwest Univ Sci & Technol, Natl Collaborat Innovat Ctr Nucl Waste & Environm, Mianyang 621010, Sichuan, Peoples R China.
    Wang, Ziwei
    Southwest Univ Sci & Technol, Natl Collaborat Innovat Ctr Nucl Waste & Environm, Mianyang 621010, Sichuan, Peoples R China.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    An emerging Janus MoSeTe material for potential applications in optoelectronic devices2019In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 39, p. 12312-12320Article in journal (Refereed)
    Abstract [en]

    Motivated by the extraordinary physical and chemical properties of Janus transition-metal dichalcogenides (TMDs) due to the change of the crystal field originating from their asymmetry structures, the electronic and optical properties of the MoSeTe monolayer in 2H and 1T phases are systematically studied by first-principles calculations, and a detailed comparison with the parental MoSe2 and MoTe2 monolayer is made. It is found that 2H-MoSeTe exhibits a direct bandgap of 1.859 eV and an indirect band gap of 0.391 eV in the 1T phase, resulting in a different way to interact with sunlight. Besides, the obtained results show that the SOC has little effects on the band gaps. The calculated optical properties show a significant red shift from the MoSe2 to MoSeTe to MoTe2 monolayer. However, a blue shift is observed from the in-plane to out-of-plane direction. Moreover, both electron-electron and electron-hole correlation effects are considered for obtaining the optical spectra of systems by G(0)W(0) and G(0)W(0) + BSE approaches. Besides, the absorption coefficient value reaches up to 1 x 10(6) cm(-1) in both phases, implying the high efficiency in the utilization of solar energy for the MoSeTe monolayer. Additionally, the 1T-MoSeTe monolayer is a good hot mirror material in that its maximum reflectivity could reach up to 51% in the infrared region. Additionally, the average optical absorbance of the Janus MoSeTe monolayer in the visible light region is calculated to be about 2% and the corresponding average transmittance is around 80%. More importantly, the difference in the optical response for the two side surfaces is considered in our work due to the intrinsic asymmetric structure of Janus MoSeTe. These results not only predict the great potential application of Janus MoSeTe in optoelectronics-electronic devices, but may enable the discovery of new optical science and the realization of various light emissions, detection, modulation and manipulation functions of specific frequencies.

  • 17.
    Zhang, Xiaoliang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Tian, Lei
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Johansson, Malin B
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Häggman, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Liu, Jianhua
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China.
    Johansson, Erik MJ
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Enhanced charge carrier extraction by a highly ordered wrinkled MgZnO thin film for colloidal quantum dot solar cells2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 42, p. 11111-11120Article in journal (Refereed)
    Abstract [en]

    Efficient charge carrier extraction from a colloidal quantum dot (CQD) solid is crucial for highperformance of CQD solar cells (CQDSCs). Herein, highly ordered wrinkled MgZnO (MZO) thin films aredemonstrated to improve the charge carrier extraction of PbS CQDSCs. The highly ordered wrinkledMZO thin films are prepared using a low-temperature combustion method. The photovoltaicperformances of CQDSCs with a combustion-processed MZO (CP-MZO) thin film as an electrontransport material (ETM) are compared to those of CQDSCs with a conventional sol–gel processed MZO(SGP-MZO) thin film as an ETM. We performed photoluminescence quenching measurements of thecolloidal quantum dot (CQD) solid and charge carrier dynamic analysis of full solar cell devices. Theresults show that the highly ordered wrinkled CP-MZO thin film significantly increases the chargecarrier extraction from the CQD solid and therefore diminishes the charge interfacial recombination atthe CQD/ETM junction, leading to a 15.5% increase in power conversion efficiency. The improvedefficiency in the CP-MZO based CQDSC is also attributed to the compact and pin-hole free CP-MZOthin film.

1 - 17 of 17
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