2014
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G. H. V. Bertrand, L. Tortech, V. Gandon, C. Aubert, et D. Fichou, « Synthesis and photovoltaic performances in solution-processed BHJs of oligothiophene-substituted organocobalt complexes [(eta(4)-C-4(nT)(4))Co(eta(5)-C5H5)] », Chemical Communications, vol. 50, nᵒ 63, p. 8663-8666, août 2014.Résumé : We describe an efficient synthetic route toward novel organocobalt complexes [(eta(4)-C-4(nT)(4))Co(eta(5)-C5H5)] with n = 1, 2, 3 thiophene rings. Solution-processed bulk heterojunctions solar cells based on CpCoCb(3T)(4):PCBM blends achieve power conversion efficiencies of up to 2.1%.
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G. Y. Y. Chng, X. Sun, S. J. Cho, D. Rajwar, A. C. Grimsdale, et D. Fichou, « Synthesis and 2D self-assembly at the liquid-solid interface of novel H-bonding linear pi-conjugated oligomers terminated by uracil and melamine units », New Journal of Chemistry, vol. 38, nᵒ 6, p. 2407-2413, juin 2014.Résumé : We report here on the synthesis and 2D self-assembly of novel H-bonding linear it-conjugated oligomers terminated at both ends by either two uracil moieties (compound GR1) or by two melamine groups (compounds GR2 and GR3). The bis(uracil) GR1 compound was prepared by Sonogashira coupling of an ethynyturacil with a dihalobenzene and characterized spectroscopically. The synthesis of GR2 and GR3 was performed by Suzuki coupling of the dihalogenated benzene derivatives leading to the respective bisadducts which were then converted into the target bis-melamine derivatives by treatment with dicyanodimide. Self-assembly of the GR1 derivative is investigated at the liquid/graphite interface using scanning tunneling microscopy (STM). When deposited from n-tetradecane, GR1 forms a row-like structure stabilized by multiple terminal H-bonds between neighboring molecules. Co-adsorption of two n-tetradecane molecules per unit cell is also clearly identified. In turn, when deposited from 1-phenyloctane GR1 forms a complex quasi square-shaped open structure having asymmetric sides. One possible arrangement is that four phenyloctane molecules are co-adsorbed in-between GR1 rows similar to those formed from n-tetradecane, thus forming the two other sides of the square-shaped motif. From both solvents, the row-like 2D arrangements are governed by the multiple terminal H-bonds which create long-range alignments in one direction and by the van der Waals interdigitation of the dodecyl chains of the GR1 molecules that stabilize the network in a nearly perpendicular direction.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates -
M. Alaaeddine, Q. Zhu, D. Fichou, G. Izzet, J.E. Rault, N. Barrett, A. Proust, et L. Tortech, « Enhancement of photovoltaic efficiency by insertion of a polyoxometalate layer at the anode of an organic solar cell », Inorg. Chem. Frontiers, vol. 1, nᵒ 9, p. 682-688, oct. 2014.Résumé : In this article the Wells–Dawson polyoxometalate K6[P2W18O62] is grown as an interfacial layer between indium tin oxide and bulk heterojunction of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The structure of the POM layers depends on the thickness and shows a highly anisotropic surface organization. The films have been characterized by atomic force microscopy and X-ray photoelectron spectroscopy (XPS) to gain insight into their macroscopic organization and better understand their electronic properties. Then, they were put at the anodic interface of a P3HT:PCBM organic solar cell and characterized on an optical bench. The photovoltaic efficiency is discussed in terms of the benefit of the polyoxometalate at the anodic interface of an organic photovoltaic cell.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates -
E. G. Petrov, A. Marchenko, O. L. Kapitanchuk, N. Katsonis, et D. Fichou, « Conductance Mechanism in a Linear Non-Conjugated Trimethylsilyl-Acetylene Molecule: Tunneling Through Localized States », Molecular Crystals and Liquid Crystals, vol. 589, nᵒ 1, p. 3-17, janv. 2014.Résumé : The conductance properties of 1,3-(trimethylsilyl)-1-tridecene-6,12-diyne, a non-conjugated trimethylsil-acetylene molecule have been investigated both experimentally and theoretically. Based on scanning tunnelling spectroscopy experiments, a discussion on the mechanisms controlling the charge transfer through this linear molecule is carried out. A specific property of the studied molecule is that it contains localized molecular orbitals. The shifts of the MOs energy levels caused by the applied voltage as well as a distant superexchange coupling between the respective localized MOs are shown to become determining in the formation of a nonlinear hole current through the molecule.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates -
H. Qi, J. Wolfe, D. Wang, H. J. Fan, D. Fichou, et Z. Chen, « Triple-layered nanostructured WO3 photoanodes with enhanced photocurrent generation and superior stability for photoelectrochemical solar energy conversion. », Nanoscale, vol. 6, nᵒ 22, p. 13457-62, oct. 2014.Résumé : Unique nanorods/nanoparticles/nanoflakes (NRs/NPs/NFs) WO3 triple-layers are grown on a metallic W foil by a simple one-step anodization method. The triple-layered structure is formed through a self-organization process, the film thickness (up to 3 mum) being controlled by the anodization time. A first layer made of an array of WO3 densely-packed vertically-aligned NRs (1.2-1.4 mum in height) grow atop the tungsten foil, followed by a second layer of small NPs (50-80 nm) and finally a third layer made of rectangular NFs (200-300 nm). When irradiated by white light in a photoelectrochemical cell these WO3 triple-layers generate a photocurrent as high as 0.9 mA cm(-2) at 1.2 V/RHE. Moreover, we show that the stability of the triple-layered WO3 photoanodes can be considerably enhanced by adding an ultrathin (10 nm) TiO2 protective overlayer.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates -
T. Salim, J. Y. Lek, B. Braeuer, D. Fichou, et Y. M. Lam, « Polymer nanofibers: preserving nanomorphology in ternary blend organic photovoltaics (vol 16, pg 23829, 2014) », Physical Chemistry Chemical Physics, vol. 16, nᵒ 47, p. 26389-26389, 2014.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates
2013
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H. Bertrand, R. Guillot, M. - P. Teulade-Fichou, et D. Fichou, « Synthesis, Properties, and Remarkable 2D Self-Assembly at the Liquid/Solid Interface of a Series of Triskele-Shaped 5,11,17-Triazatrinaphthylenes (TrisK) », Chemistry – A European Journal, vol. 19, nᵒ 43, p. 14654-14664, oct. 2013.Résumé : A series of 5,11,17-triazatrinaphthylene (TrisK) derivatives, large disk-like p-conjugated molecules with C-3h symmetry, has been synthesised by following an optimised synthetic pathway. The synthesis was performed by a four-step protocol based on the N-arylation of 1,3,5-tribromobenzene with appropriate anthranilate derivatives. This strategy permits the generation of either chlorinated (TrisK-Cl-OCn) or non-chlorinated (TrisK-H-OCn) alkoxy-substituted derivatives (OCnH2n+1 with n=3, 10, 12 and 16), thus providing additional versatility in the control of the structure-property relationships. The electronic properties of the various TrisK compounds have been characterised in solution by absorption and emission spectroscopies as well as cyclic voltammetry. The crystal structure of 2,8,14-propyloxy-5,11,17-triazatrinaphthylene TrisK-H-OC3 has been determined by X-ray diffraction analysis, which revealed the presence of stabilising weak intermolecular H bonds. Scanning tunnelling microscopy (STM) at the liquid/solid interface has revealed the remarkable 2D self-assembling properties of the TrisK compounds. In particular, it has shown that TrisK-H-OC12 forms three concomitant self-organised 2D phases with different row-packing arrangements. This 2D polymorphism arises from slow ordering due to the presence of three long dodecyloxy chains on the molecular backbone. Individual molecules can be imaged with spectacular intramolecular resolution, thus providing the possibility of correlating the STM features with the calculated charge density distribution.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates -
C. Blouzon, F. Ott, L. Tortech, D. Fichou, et J. - B. Moussy, « Anti-ferromagnetic coupling in hybrid magnetic tunnel junctions mediated by monomolecular layers of alpha-sexithiophene », Applied Physics Letters, vol. 103, nᵒ 4, p. 042417, juill. 2013.Résumé : We report here on the magnetic coupling taking place between Fe3O4 and Co layers across an organic monolayer of alpha-sexithiophene (6T). The controlled growth of 6T ultrathin films on epitaxial Fe3O4 surfaces allows to prepare highly homogeneous insulating layers with thicknesses in the range 0.5-2.0 monolayers (ML). A combined study using vibrating sample magnetometry and polarized neutron reflectivity reveals that hybrid Fe3O4/6T/Co tunnel junctions show different magnetic couplings depending on the 6T thickness. In particular, magnetic coupling between Fe3O4 and Co layers separated by 1 ML of 6T is consistent with anti-ferromagnetic coupling, opening new perspectives for controlling magnetization in organic spintronic devices. (C) 2013 AIP Publishing LLC.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates -
D. Fichou, S. Berny, et L. Tortech, « Derivatives of Dipyrannylidene Type as Anode Interface Layer in Electronic Devices. », U.S. Patent US Patent N°8,383,9312013.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates -
A. Nion, N. Katsonis, A. Marchenko, C. Aubert, et D. Fichou, « Influence of molecular length on the adsorption of linear trimethylsilylacetylene derivatives at the n-tetradecane/Au(111) interface: chemisorption vs. physisorption », New Journal of Chemistry, vol. 37, nᵒ 8, p. 2261-2265, 2013.Résumé : Adsorption of two trimethylsilylacetylene (TMSA) derivatives bearing linear alkyl chains of different lengths has been studied at the n-tetradecane/Au(111) interface. The lying or standing orientation of TMSA compounds on the gold surface shows that adsorption is not only controlled by the chemical reactivity of the molecules but also by their size.
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A. Pancotti, J. Wang, P. Chen, L. Tortech, C. - M. Teodorescu, E. Frantzeskakis, et N. Barrett, « X-ray photoelectron diffraction study of relaxation and rumpling of ferroelectric domains in BaTiO3(001) », Physical Review B, vol. 87, nᵒ 18, p. 184116, mai 2013.Résumé : The surface of a ferroelectric BaTiO3(001) single crystal was studied using synchrotron radiation induced x-ray photoelectron diffraction (XPD), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and low-energy electron diffraction (LEED). AFM, XPS, and LEED show that the surface is BaO terminated with a (1 x 1) reconstruction. The Ba 4d, Ti 2p, and O 1s XPD results were compared with multiple scattering simulations for out-of- (P+, P) and in-plane (P-in) polarizations using a genetic algorithm to determine atomic rumpling and interlayer relaxation. Linear combinations of the XPD simulations of the surface structure of each polarization state allow determination of the domain ordering. The best agreement with experiment is found for 55% P+, 38% P-, and 7% P-in. The rumpling is smaller at the surface than in the bulk, suggesting that both domain ordering and surface structural changes contribute to screening of the polarization.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates
2012
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G. Bertrand, L. Tortech, D. Fichou, M. Malacria, C. Aubert, et V. Gandon, « An Improved Protocol for the Synthesis of [(η4-C4R4)Co(η5-C5H5)] Complexes », Organometallics, vol. 31, nᵒ 1, p. 126-132, janv. 2012.Résumé : The reaction of bulky alkynes C2R2 with (?5-C5H5)Co(CO)(dimethyl fumarate) under microwave irradiation provides complexes of the type [(?4-C4R4)Co(?5-C5H5)] in good to excellent yields. This protocol represents a significant improvement over those reported previously. In particular, the formation of insertion products such as cyclopentadienones or cyclohexadienes can be avoided. In addition, because of the exceptional stability of (?5-C5H5)Co(CO)(dimethyl fumarate), the reactions can be carried out in crude solvents. The easy access to [(?4-C4R4)Co(?5-C5H5)] complexes stimulated a study of their reactivity, notably under cross-coupling conditions.Exporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates -
D. Rajwar, X. Sun, S. J. Cho, A. C. Grimsdale, et D. Fichou, « Synthesis and 2D self-assembly at the liquid-solid interface of end-substituted star-shaped oligophenylenes », CrystEngComm, vol. 14, nᵒ 16, p. 5182-5187, juill. 2012.Résumé : We report here on the synthesis and self-assembly of four star-shaped trigonal 1,3,5-tris-(1,1-biphenyl-4-yl)-benzene (TBB) derivatives substituted by different functional groups on the terminal positions of the three arms of the molecule: COOCH3 (1), COOH (2), NH2 (3), and CN (4). Self-assembly of the triesExporter la référence : BibTeX | MODS | Refer/BibIX | Bibliographic Ontology RDF | Unqualified Dublin Core RDF | Zotero RDF | RIS (EndNote) | Wikipedia Citation Templates
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