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  • 51.
    Palma, Carlos-Andres
    et al.
    Technishe Universität München, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Klappenberger, Florian
    Technische Universität München, Germany.
    Arras, Emmanuel
    Technische Universität München, Germany.
    Kühne, Dirk
    Technische Universität München, Germany.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Barth, Johannes V.
    Technische Universität München, Germany.
    Visualization and thermodynamic encoding of single-molecule partition function projections2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, no 6210Article in journal (Refereed)
    Abstract [en]

    Ensemble averaging of molecular states is fundamental for the experimental determination of thermodynamic quantities. A special case occurs for single-molecule investigations under equilibrium conditions, for which free energy, entropy and enthalpy at finite temperatures are challenging to determine with ensemble averaging alone. Here we report a method to directly record time-averaged equilibrium probability distributions by confining an individual molecule to a nanoscopic pore of a two-dimensional metal-organic nanomesh, using temperature-controlled scanning tunnelling microscopy. We associate these distributions with partition function projections to assess real-space-projected thermodynamic quantities, aided by computational modelling. The presented molecular dynamics-based analysis is able to reproduce experimentally observed projected microstates with high accuracy. By an in silico customized energy landscape, we demonstrate that distinct probability distributions can be encrypted at different temperatures. Such modulation provides means to encode and decode information into position–temperature space.

  • 52.
    Pop, Flavia
    et al.
    University of Angers, France.
    Melan, Caroline
    University of Angers, France.
    Danila, Ion
    University of Angers, France.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Beljonne, David
    University of Mons, Belgium.
    Amabilino, David B.
    Insitut Ciencia Mat Barcelona ICMAB CSIC, Spain.
    Avarvari, Narcis
    University of Angers, France.
    Hierarchical Self-Assembly of Supramolecular Helical Fibres from Amphiphilic C3-Symmetrical Functional Tris(tetrathiafulvalenes)2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 52, p. 17443-17453Article in journal (Refereed)
    Abstract [en]

    The preparation and self-assembly of the enantiomers of a series of C-3-symmetric compounds incorporating three tetrathiafulvalene (TTF) residues is reported. The chiral citronellyl and dihydrocitronellyl alkyl chains lead to helical one dimensional stacks in solution. Molecular mechanics and dynamics simulations combined with experimental and theoretical circular dichroism support the observed helicity in solution. These stacks self-assemble to give fibres that have morphologies that depend on the nature of the chiral alkyl group and the medium in which the compounds aggregate. An inversion of macroscopic helical morphology of the citronellyl compound is observed when compared to analogous 2-methylbutyl chains, which is presumably a result of the stereogenic centre being further away from the core of the molecule. This composition still allows both morphologies to be observed, whereas an achiral compound shows no helicity. The morphology of the fibres also depends on the flexibility at the chain ends of the amphiphilic components, as there is not such an apparently persistent helical morphology for the dihydrocitronellyl derivative as for that prepared from citronellyl chains.

  • 53.
    Qian, Deping
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Liu, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Wang, Suhao
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Himmelberger, Scott
    Stanford University, CA 94305 USA.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Muller, Christian
    Chalmers, Sweden.
    Zaifei, Zaifei
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Salleo, Alberto
    Stanford University, CA 94305 USA.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zou, Yingping
    Central S University, Peoples R China.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Modulating molecular aggregation by facile heteroatom substitution of diketopyrrolopyrrole based small molecules for efficient organic solar cells2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 48, p. 24349-24357Article in journal (Refereed)
    Abstract [en]

    In conjugated polymers and small molecules of organic solar cells, aggregation induced by intermolecular interactions governs the performance of photovoltaics. However, little attention has been paid to the connection between molecular structure and aggregation within solar cells based on soluble small molecules. Here we demonstrate modulation of intermolecular aggregation of two synthesized molecules through heteroatom substitution to develop an understanding of the role of aggregation in conjugated molecules. Molecule 1 (M1) based on 2-ethylhexyloxy-benzene substituted benzo[1,2-b:4,5-b]dithiophene (BDTP) and diketopyrrolopyrrole (DPP) displays strong aggregation in commonly used organic solvents, which is reduced in molecule 2 (M2) by facile oxygen atom substitution on the BDTP unit confirmed by absorption spectroscopy and optical microscopy, while it successfully maintains molecular planarity and favorable charge transport characteristics. Solar cells based on M2 exhibit more than double the photocurrent of devices based on M1 and yield a power conversion efficiency of 5.5%. A systematic investigation of molecular conformation, optoelectronic properties, molecular packing and crystallinity as well as film morphology reveals structure dependent aggregation responsible for the performance difference between the two conjugated molecules.

  • 54.
    Rastgoo Lahrood, Atena
    et al.
    Technical University of Munich, Germany; Nanosyst Initiat Munich, Germany; Centre NanoScience, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Heckl, Wolfgang M.
    Technical University of Munich, Germany; Nanosyst Initiat Munich, Germany; Centre NanoScience, Germany; Deutsch Museum, Germany.
    Lackinger, Markus
    Technical University of Munich, Germany; Nanosyst Initiat Munich, Germany; Centre NanoScience, Germany; Deutsch Museum, Germany.
    1,3-Diiodobenzene on Cu(111) - an exceptional case of on-surface Ullmann coupling2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 68, p. 13301-13304Article in journal (Refereed)
    Abstract [en]

    Ullmann coupling of 1,3-diiodobenzene is studied on Cu(111) surfaces in ultra-high vacuum (UHV). In situ Scanning Tunneling Microscopy (STM) at room temperature revealed an unexpected ordered arrangement of highly uniform reaction products adsorbed atop a closed iodine monolayer.

  • 55.
    Ribeiro Junior, Luiz Antonio
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering. University of Brasilia, Brazil; University of Brasilia, Brazil.
    Santiago de Brito, Sara
    University of Brasilia, Brazil.
    Henrique de Oliveira Neto, Pedro
    University of Brasilia, Brazil.
    Trap-assisted charge transport at conjugated polymer interfaces2016In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 644, p. 121-126Article in journal (Refereed)
    Abstract [en]

    The trap-assisted charge transport in conjugated polymers is numerically investigated in the framework of a one-dimensional tight-binding model. Our findings show that a polaron trapped within an interchain region can be released migrating between the chains at low temperature regimes. Conversely, a trapped bipolaron cannot be released even considering high temperature values. Interestingly, for systems containing more than one polaron, the formation of trapped states is avoided and there is no charge transfer between the chains. Considering more than one bipolaron, the generation of trapped states occurs and a bipolaron can migrates between the chains. (C) 2015 Elsevier B.V. All rights reserved.

  • 56.
    Ribeiro, Luiz Antonio
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Ferreira da Cunha, Wiliam
    University of Brasilia, Brazil.
    Luciano de Almeida Fonseca, Antonio
    University of Brasilia, Brazil.
    Magela e Silva, Geraldo
    University of Brasilia, Brazil.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Transport of Polarons in Graphene Nanoribbons2015In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 6, no 3, p. 510-514Article in journal (Refereed)
    Abstract [en]

    The field-induced dynamics of polarons in armchair graphene nanoribbons (GNRs) is theoretically investigated in the framework of a two-dimensional tight-binding model with lattice relaxation. Our findings show that the semiconductor behavior, fundamental to polaron transport to take place, depends upon of a suitable balance between the GNR width and the electronphonon (eph) coupling strength. In a similar way, we found that the parameter space for which the polaron is dynamically stable is limited to an even narrower region of the GNR width and the eph coupling strength. Interestingly, the interplay between the external electric field and the eph coupling plays the role to define a phase transition from subsonic to supersonic velocities for polarons in GNRs.

  • 57.
    Ribeiro, Luiz Antonio
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering. University of Brasilia, Brazil; University of Brasilia, Brazil.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Impact of the electron-phonon coupling symmetry on the polaron stability and mobility in organic molecular semiconductors2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 3, p. 1386-1391Article in journal (Refereed)
    Abstract [en]

    The influence of the interplay between symmetric and antisymmetric inter-molecular electron-phonon (e-ph) coupling mechanisms on the polaron stability and mobility in organic semiconductors has been theoretically investigated at a molecular level. A semi-empirical Holstein-Peierls model is used which in addition to the symmetric and antisymmetric inter-molecular e-ph interactions also includes an antisymmetric intra-molecular e-ph coupling. Our results show that the symmetric e-ph coupling plays the role of destabilizing the polaron as a result of temperature induced phonons that, via the symmetric coupling, affects the charge distribution of the polaron. Considering this kind of coupling, the parameter space for which the polaron is dynamically stable is strongly temperature-dependent. For the combination of symmetric e-ph coupling strength and temperature, which results in a stable polaron, the velocity of the polaron, and therefore also the charge carrier mobility, is not affected by the symmetric e-ph coupling strength.

  • 58.
    Rinkevicius, Zilvinas
    et al.
    KTH Royal Institute Technology, Sweden.
    Sandberg, Jaime A. R.
    KTH Royal Institute Technology, Sweden.
    Li, Xin
    KTH Royal Institute Technology, Sweden.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Ågren, Hans
    KTH Royal Institute Technology, Sweden.
    Hybrid Complex Polarization Propagator/Molecular Mechanics Method for Heterogeneous Environments2016In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 12, no 6, p. 2661-2667Article in journal (Refereed)
    Abstract [en]

    We introduce a hybrid complex polarization propagator/molecular mechanics method for the calculation of near-resonant and resonant response properties of molecules in heterogeneous environments, which consist of a metallic surface, or nanoparticle, and a solvent. The applicability and performance of the method is demonstrated by computations of linear absorption spectra of p-nitroaniline physisorbed at a gold/dimethyl sulfoxide interface in the UV/vis and near carbon-K-edge regions of the spectrum. It is shown that the shift of absorption cross-section induced by the heterogeneous environment varies significantly depending on the nature,of the excited states encountered in the targeted frequency region as well as on the actual size of the resonant frequencies, and that the solvent component of the heterogeneous environment is responsible for the major part of the environmental shift, especially in the higher frequency range of the carbon K-edge region.

  • 59.
    Rubio-Magnieto, Jenifer
    et al.
    University of Mons UMONS, Belgium.
    Di Meo, Florent
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Lo, Mamadou
    University of Montpellier 2, France.
    Delcourt, Cecile
    University of Mons UMONS, Belgium.
    Clement, Sebastien
    University of Montpellier 2, France.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Richeter, Sebastien
    University of Montpellier 2, France.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology. University of Mons UMONS, Belgium.
    Surin, Mathieu
    University of Mons UMONS, Belgium.
    Binding modes of a core-extended metalloporphyrin to human telomeric DNA G-quadruplexes2015In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 13, no 8, p. 2453-2463Article in journal (Refereed)
    Abstract [en]

    The molecular recognition of human telomeric G-quadruplexes by a novel cationic pi-extended Ni-II-porphyrin (Ni-II-TImidP4) is studied in aqueous solutions via (chir) optical spectroscopy, Fluorescence Resonance Energy Transfer (FRET) melting assay, and computational molecular modeling. The results are systematically compared with the recognition by a conventional meso-substituted Ni-II-porphyrin (Ni-II-TMPyP4), which allows us to pinpoint the differences in binding modes depending on the G-quadruplex topology. Importantly, FRET melting assays show the higher selectivity of Ni-II-TImidP4 towards human telomeric G4 than that of Ni-II-TMPyP4.

  • 60.
    Rustioni, L.
    et al.
    University of Milan, Italy.
    Rocchi, L.
    University of Milan, Italy.
    Di Meo, Florent
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Failla, O.
    University of Milan, Italy.
    Trouillas, P.
    University of Limoges, France; Palacky University of Olomouc, Czech Republic.
    Advances in grape phenotyping: pigment characterization by reflectance and theoretical chemistry2015In: Vitis, ISSN 0042-7500, Vol. 54, no SI, p. 173-174Article in journal (Refereed)
    Abstract [en]

    n/a

  • 61.
    Saidi, Wissam A.
    et al.
    University of Pittsburgh, PA 15261 USA.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering. KTH Royal Institute Technology, Sweden.
    Polarizabilities and van der Waals C-6 coefficients of fullerenes from an atomistic electrodynamics model: Anomalous scaling with number of carbon atoms2016In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 145, no 2, p. 024311-Article in journal (Refereed)
    Abstract [en]

    The van der Waals C-6 coefficients of fullerenes are shown to exhibit an anomalous dependence on the number of carbon atoms N such that C-6 proportional to N-2.2 as predicted using state-of-the-art quantum mechanical calculations based on fullerenes with small sizes, and N-2.75 as predicted using a classical-metallic spherical-shell approximation of the fullerenes. We use an atomistic electrodynamics model where each carbon atom is described by a polarizable object to extend the quantum mechanical calculations to larger fullerenes. The parameters of this model are optimized to describe accurately the static and complex polarizabilities of the fullerenes by fitting against accurate ab initio calculations. This model shows that C-6 proportional to N-2.8, which is supportive of the classical-metallic spherical-shell approximation. Additionally, we show that the anomalous dependence of the polarizability on N is attributed to the electric charge term, while the dipole-dipole term scales almost linearly with the number of carbon atoms. Published by AIP Publishing.

  • 62.
    Schall, Anna P.
    et al.
    Haverford Coll, PA 19041 USA.
    Iavicoli, Patrizia
    CSIC, Spain.
    John Qi, Zhengling
    University of Penn, PA 19104 USA.
    Menko, Julien
    Haverford Coll, PA 19041 USA.
    Lu, Ye
    University of Penn, PA 19104 USA.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    de Paula, Julio C.
    Lewis and Clark Coll, OR 97219 USA.
    Amabilino, David B.
    CSIC, Spain.
    Johnson, A. T.
    University of Penn, PA 19104 USA.
    Smith, Walter F.
    Haverford Coll, PA 19041 USA.
    Photoconductivity of Nanofilaments That are Self-Assembled from a Porphyrin with Long Alkyl-Chain Substituents2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 46, p. 26154-26163Article in journal (Refereed)
    Abstract [en]

    Photoelectronically active nanostructures that are Self-assembled from organic rnolecules hold the prortu se of tailored functionality.with simple and inexpensive production. Comparison of nanoWires assembled from related componnds can give important insightS into the details of self-assembly and the,conduction meehanisms. We report the photoconductivity of nanofibers that are self-assembled from a porphyrin With long alkyl substituents. In contrast to previously studied porphyrin nanowires, the photoconductivity increases as atthospheric O-2 is increased. This can be explained-using the same model aS used in the previous studies, by assuming a different, line-up of the bands of the nanofilaments. with the electrode Fermi level. However, this model does not explain our observation that-at O-2 concentrations above 1%, the conduction increases with continued- illunation; this may be due to photoactivation of shallow O-2 adsorption sites. The overall conduction level is low even at high O-2 Concentration, because the alkyl substituents form an insulating sheath around the rianofibers. Such inSulation could be valuable in applications where it would prevent cross-talk between signal S darried in different nanofilaments. Schottky barriers at the interface between- organic nanostructures and electrodes strongly affect conduction and photoconduction, and are strongly influenced by atmospheric gases such, as O-2.

  • 63.
    Shirani, Hamid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Sigurdson, Christina J.
    University of Calif San Diego, CA 92093 USA.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    A Palette of Fluorescent Thiophene-Based Ligands for the Identification of Protein Aggregates2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 43, p. 15133-15137Article in journal (Refereed)
    Abstract [en]

    By replacing the central thiophene unit of an anionic pentameric oligothiophene with other heterocyclic moities, a palette of pentameric thiophene-based ligands with distinct fluorescent properties were synthesized. All ligands displayed superior selectivity towards recombinant amyloid fibrils as well as disease-associated protein aggregates in tissue sections.

  • 64.
    Trouillas, Patrick
    et al.
    University of Limoges, France; Palacky University, Czech Republic.
    Di Meo, Florent
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Gierschner, Johannes
    Madrid Institute Adv Studies IMDEA Nanosci, Spain.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Carlos Sancho-Garcia, Juan
    University of Alicante, Spain.
    Otyepka, Michal
    Palacky University, Czech Republic.
    Optical properties of wine pigments: theoretical guidelines with new methodological perspectives2015In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 71, no 20, p. 3079-3088Article in journal (Refereed)
    Abstract [en]

    Wine pigmentation results from the complex chemistry of anthocyanins. Their flavylium cation form is stabilized either by chemical transformation occurring during wine aging (e.g., pyranoanthocyanin formation), or by the formation of non-covalent complexes with (phenolic) copigments. Molecular modeling (quantum mechanics and molecular dynamics) is more and more adapted to understand wine chemistry and pigmentation. The constant developments of theoretical methodologies might get non-specialists easily lost. This manuscript is a review of the theoretical studies dedicated to the field of wine pigments, showing conformational analysis, energetics of the various forms, pigment/copigment (non-)covalent association, and charge transfer excited states. QM/MM calculations are newly performed here, which improve solvent description. The conclusion is a comprehensive guideline for an accurate prediction of light absorption by wine pigments and all related supramolecular processes.

  • 65.
    Volpi, Riccardo
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Charge Transport Simulations for Organic Electronics: A Kinetic Monte Carlo Approach2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis we focus on the modelling and simulation of organic electronic devices, investigating their structural and electronic properties. Organic devices have attracted great interest for their innovative properties, but their functioning still represent a theoretical and technological challenge. They are composed by one or more organic materials depending on the particular application. The morphology of organic devices in the single phase or at the interface is known to strongly determine mobility and efficiency of the devices. The structural disorder is studied through molecular dynamics (MD) simulations. Marcus formula is used to calculate the hopping rate of the charge carriers and the model developed is tested by simulations in a Kinetic Monte Carlo scheme. The dependence of the transfer integrals on the relative molecular orientation is achieved through a weighted Mulliken formula or through a dimer projection approach using the semi-empirical Hartree Fock method ZINDO. Electrostatic effects, have been included through atomic charges and atomic polarizabilities, calculated at the B3LYP level of theory. The inclusion of electrostatic effects has been shown (through simulations in 4PV and C60) to be crucial to obtain a good qualitative agreement with experiments, for both mobility field and temperature dependence in the single phase. In particular the external reorganization energy, calculated through the polarization of the environment, has been shown to have a great impact on the conduction, shifting the inverse Marcus region and helping CT state separation at the interface (between C60 and anthracene).

    List of papers
    1. Transition fields in organic materials: From percolation to inverted Marcus regime. A consistent Monte Carlo simulation in disordered PPV
    Open this publication in new window or tab >>Transition fields in organic materials: From percolation to inverted Marcus regime. A consistent Monte Carlo simulation in disordered PPV
    2015 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, no 9, p. 094503-Article in journal (Refereed) Published
    Abstract [en]

    In this article, we analyze the electric field dependence of the hole mobility in disordered poly (p-phenylene vinylene). The charge carrier mobility is obtained from Monte Carlo simulations. Depending on the field strength three regions can be identified: the percolation region, the correlation region, and the inverted region. Each region is characterized by a different conduction mechanism and thus a different functional dependence of the mobility on the electric field. Earlier studies have highlighted that Poole-Frenkel law, which appears in the correlation region, is based on the type of correlation caused by randomly distributed electric dipoles. This behavior is thus observed in a limited range of field strengths, and by studying a broader range of electric fields, a more fundamental understanding of the transport mechanism is obtained. We identify the electric fields determining the transitions between the different conduction mechanisms in the material and we explain their physical origin. In principle, this allows us to characterize the mobility field dependence for any organic material. Additionally, we study the charge carrier trapping mechanisms due to diagonal and off-diagonal disorder, respectively. (C) 2015 AIP Publishing LLC.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2015
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-117234 (URN)10.1063/1.4913733 (DOI)000350973900041 ()25747090 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council (VR); MATTER Network; SERC (Swedish e-Science Research Center)

    Available from: 2015-04-22 Created: 2015-04-21 Last updated: 2017-12-04
    2. Effect of Polarization on the Mobility of C60: A Kinetic Monte-Carlo Study
    Open this publication in new window or tab >>Effect of Polarization on the Mobility of C60: A Kinetic Monte-Carlo Study
    Show others...
    2016 (English)In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 12, no 2, p. 812-824Article in journal (Refereed) Published
    Abstract [en]

    We present a study of mobility field and temperature dependence for C60 with Kinetic Monte-Carlo simulations. We propose a new scheme to take into account polarization effects in organic materials through atomic induced dipoles on nearby molecules. This leads to an energy correction for the single site energies and to an external reorganization happening after each hopping. The inclusion of polarization allows us to obtain a good agreement with experiments for both mobility field and temperature dependence.

    Place, publisher, year, edition, pages
    American Chemical Society (ACS), 2016
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-122989 (URN)10.1021/acs.jctc.5b00975 (DOI)000370112900032 ()
    Note

    Vid tiden för disputation förelåg publikationen endast som manuskript

    Funding agencies:  SeRC (Swedish e-Science Research Center)

    Available from: 2015-12-01 Created: 2015-12-01 Last updated: 2017-12-01Bibliographically approved
    3. Charge-transfer state dynamics at C60-anthracene interfaces: a kinetic Monte Carlo approach
    Open this publication in new window or tab >>Charge-transfer state dynamics at C60-anthracene interfaces: a kinetic Monte Carlo approach
    2015 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The morphology of organic interfaces plays an important role in charge-transfer (CT) state splitting, and therefore has a significant impact on the efficiency of organic solar cells. In this article, we use our kinetic Monte Carlo (KMC) method on molecular dynamics-simulated anthracene-C60 interfaces to study the relation between interface morphology and CT state splitting. These KMC simulations were performed at a range of applied electric fields, and with the fields applied at a range of angles to the interface. The results show that depending on the relative orientation of the anthracene and C60 molecules, CT state splitting shows different behavior with respect to both applied field strength and applied field angle. Different orientations may be better suited for different applications. The inclusion of polarization in our model is shown to  increase CT state splitting for both orientations studied.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-122990 (URN)
    Available from: 2015-12-01 Created: 2015-12-01 Last updated: 2015-12-01Bibliographically approved
  • 66.
    Volpi, Riccardo
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Kottravel, Sathish
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Norby, Morten Sten
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Denmark.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Effect of Polarization on the Mobility of C60: A Kinetic Monte-Carlo Study2016In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 12, no 2, p. 812-824Article in journal (Refereed)
    Abstract [en]

    We present a study of mobility field and temperature dependence for C60 with Kinetic Monte-Carlo simulations. We propose a new scheme to take into account polarization effects in organic materials through atomic induced dipoles on nearby molecules. This leads to an energy correction for the single site energies and to an external reorganization happening after each hopping. The inclusion of polarization allows us to obtain a good agreement with experiments for both mobility field and temperature dependence.

  • 67.
    Volpi, Riccardo
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Nassau, Racine
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Charge-transfer state dynamics at C60-anthracene interfaces: a kinetic Monte Carlo approach2015Manuscript (preprint) (Other academic)
    Abstract [en]

    The morphology of organic interfaces plays an important role in charge-transfer (CT) state splitting, and therefore has a significant impact on the efficiency of organic solar cells. In this article, we use our kinetic Monte Carlo (KMC) method on molecular dynamics-simulated anthracene-C60 interfaces to study the relation between interface morphology and CT state splitting. These KMC simulations were performed at a range of applied electric fields, and with the fields applied at a range of angles to the interface. The results show that depending on the relative orientation of the anthracene and C60 molecules, CT state splitting shows different behavior with respect to both applied field strength and applied field angle. Different orientations may be better suited for different applications. The inclusion of polarization in our model is shown to  increase CT state splitting for both orientations studied.

  • 68.
    Volpi, Riccardo
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, The Institute of Technology.
    Transition fields in organic materials: From percolation to inverted Marcus regime. A consistent Monte Carlo simulation in disordered PPV2015In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, no 9, p. 094503-Article in journal (Refereed)
    Abstract [en]

    In this article, we analyze the electric field dependence of the hole mobility in disordered poly (p-phenylene vinylene). The charge carrier mobility is obtained from Monte Carlo simulations. Depending on the field strength three regions can be identified: the percolation region, the correlation region, and the inverted region. Each region is characterized by a different conduction mechanism and thus a different functional dependence of the mobility on the electric field. Earlier studies have highlighted that Poole-Frenkel law, which appears in the correlation region, is based on the type of correlation caused by randomly distributed electric dipoles. This behavior is thus observed in a limited range of field strengths, and by studying a broader range of electric fields, a more fundamental understanding of the transport mechanism is obtained. We identify the electric fields determining the transitions between the different conduction mechanisms in the material and we explain their physical origin. In principle, this allows us to characterize the mobility field dependence for any organic material. Additionally, we study the charge carrier trapping mechanisms due to diagonal and off-diagonal disorder, respectively. (C) 2015 AIP Publishing LLC.

  • 69.
    Yang, Biao
    et al.
    Soochow University, Peoples R China.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Lin, Haiping
    Soochow University, Peoples R China.
    Zhang, Xiaoqing
    Soochow University, Peoples R China.
    Zhang, Haiming
    Soochow University, Peoples R China.
    Li, Youyong
    Soochow University, Peoples R China.
    Fan, Jian
    Soochow University, Peoples R China.
    Li, Qing
    Soochow University, Peoples R China.
    Chi, Lifeng
    Soochow University, Peoples R China.
    Synthesis of Surface Covalent Organic Frameworks via Dimerization and Cyclotrimerization of Acetyls2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 15, p. 4904-4907Article in journal (Refereed)
    Abstract [en]

    The formation of additional phenyl rings on surfaces is of particular interest because it allows for the building-up of surface covalent organic frameworks. In this work, we show for the first time that the cyclotrimerization of acetyls to aromatics provides a promising approach to 2D conjugated covalent networks on surfaces under ultrahigh vacuum. With the aid of scanning tunneling microscopy, we have systematically studied the reaction pathways and the products. With the combination of density functional theory calculations and X-ray photoemission spectroscopy, the surface-assisted reaction mechanism, which is different from that in solution, was explored.

  • 70.
    Zhang, Yi-Qi
    et al.
    Technical University of Munich, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Barth, Johannes V.
    Technical University of Munich, Germany.
    Klappenberger, Florian
    Technical University of Munich, Germany.
    Intermolecular Hybridization Creating Nanopore Orbital in a Supramolecular Hydrocarbon Sheet2016In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 16, no 7, p. 4274-4281Article in journal (Refereed)
    Abstract [en]

    Molecular orbital engineering is a key ingredient for the design of organic devices. Intermolecular hybridization promises efficient charge carrier transport but usually requires dense packing for significant wave function overlap. Here we use scanning tunneling spectroscopy to spatially resolve the electronic structure of a surface-confined nanoporous supramolecular sheet of a prototypical hydrocarbon compound featuring terminal alkyne (CCH) groups. Surprisingly, localized nanopore orbitals are observed, with their electron density centered in the cavities surrounded by the functional moieties. Density functional theory calculations reveal that these new electronic states originate from the intermolecular hybridization of six in-plane x-orbitals of the carbon carbon triple bonds, exhibiting significant electronic splitting and an energy downshift of approximately 1 eV. Importantly, these nanopore states are distinct from previously reported interfacial states. We unravel the underlying connection between the formation of nanopore orbital and geometric arrangements of functional groups, thus demonstrating the generality of applying related orbital engineering concepts in various types of porous organic structures.

  • 71.
    Zhang, Yi-Qi
    et al.
    Technical University of Munich, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Weber, Peter
    Technical University of Munich, Germany.
    Hellwig, Raphael
    Technical University of Munich, Germany.
    Diller, Katharina
    Technical University of Munich, Germany.
    Papageorgiou, Anthoula C.
    Technical University of Munich, Germany.
    Cheol Oh, Seung
    Technical University of Munich, Germany.
    Fischer, Sybille
    Technical University of Munich, Germany.
    Allegretti, Francesco
    Technical University of Munich, Germany.
    Klyatskaya, Svetlana
    Karlsruhe Institute Technology, Germany.
    Ruben, Mario
    Karlsruhe Institute Technology, Germany; University of Strasbourg, France.
    Barth, Johannes V.
    Technical University of Munich, Germany.
    Klappenberger, Florian
    Technical University of Munich, Germany.
    Unusual Deprotonated Alkynyl Hydrogen Bonding in Metal-Supported Hydrocarbon Assembly2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 17, p. 9669-9679Article in journal (Refereed)
    Abstract [en]

    We demonstrate that terminal alkynyl moieties represent powerful functional groups for driving thermally stable, on-surface supramolecular structure formation on a reactive substrate. Through a combination of scanning tunneling microscopy, X-ray photoelectron spectroscopy, near-edge X-ray absorption-fine-structure spectroscopy and density functional theory calculations, we investigate the molecule-surface interaction and self-assembly of two prototypical hydrocarbon species on Cu(111). For 1,3,5-tris(4-ethynylphenyl)benzene (Ext-TEB) adsorption at low temperature (200 K) results in nonassembling, conformationally adapted intact species. Deprotonation of the terminal alkyne moieties, taking place at temperatures ranging from 300 to 350 K, triggers the formation of room-temperature stable, close-packed supramolecular islands. Through DFT calculations, the stabilizing interaction is identified as a trifurcated ionic C-H center dot center dot center dot pi(-delta) hydrogen bonding between the g-system of the ionic alkynyl groups and methine moieties of nearby benzene rings, providing an energy gain of 0.26 eV/molecule upon network formation. Robust assemblies result from the combination of this weak directional attraction with the strong surface anchoring also provided by the alkynyl groups. The generality of this novel ionic hydrogen-bonding type is demonstrated by the observation of low-dimensional assemblies of 9,10-diethynyl-anthracene on the same surface, consistently explained with the same type of interaction.

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