| 1. |
- Crivillers, N, et al.
(author)
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Photoinduced work function changes by isomerization of a densely packed azobenzene-based SAM on Au: a joint experimental and theoretical study
- 2011
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 13:32, s. 14302-14310
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Journal article (peer-reviewed)abstract
- Responsive monolayers are key building blocks for future applications in organic and molecular electronics in particular because they hold potential for tuning the physico-chemical properties of interfaces, including their energetics. Here we study a photochromic SAM based on a conjugated azobenzene derivative and its influence on the gold work function (Phi(Au)) when chemisorbed on its surface. In particular we show that the Phi(Au) can be modulated with external stimuli by controlling the azobenzene trans/cis isomerization process. This phenomenon is characterized experimentally by four different techniques, kelvin probe, kelvin probe force microscopy, electroabsorption spectroscopy and ultraviolet photoelectron spectroscopy. The use of different techniques implies exposing the SAM to different measurement conditions and different preparation methods, which, remarkably, do not alter the observed work function change (Phi(trans)-Phi(cis)). Theoretical calculations provided a complementary insight crucial to attain a deeper knowledge on the origin of the work function photo-modulation.
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| 2. |
- Bröms, P., et al.
(author)
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Optical absorption studies of sodium doped poly(cyanoterephthalylidene)
- 1994
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In: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 67:1-3, s. 93-96
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Journal article (peer-reviewed)abstract
- The effects of doping poly(cyanoterephthalylidene) with sodium in ultrahighvacuum been studied by optical absorption spectroscopy. Upon doping, new optical transitions are observed within the bandgap; the characteristics of these transitions are consistent with the formation of bipolarons. The optical absorption results are confirmed by direct measurements of the doping-induced gap states using ultraviolet photoelectron spectroscopy.
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| 3. |
- Crispin, Annica, et al.
(author)
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Influence of dopant on the electronic structure of spiro-oligophenyl-based disordered organic semiconductors
- 2002
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 116:18, s. 8159-8167
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Journal article (peer-reviewed)abstract
- The influence of the dopant on the electronic structure of spiro-oligophenyl-based disordered organic semiconductors was studied by means of photoelectron spectroscopy. With lithium atoms as dopants, two charges were stored on the same spiro branch in the form of bipolarons, for spiro-quarterphenyl and spiro-sexiphenyl. For doping with the sodium atoms, the size of the counter ions made it less energetically desirable to store two charges onto a single branch, and the charged species were polarons independent of the level of doping which was confirmed by optical absorption data.
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| 4. |
- Crispin, Xavier, 1972-, et al.
(author)
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Photochromic Diodes
- 2006. - 2
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In: Semiconducting Polymers. - Weinheim, Tyskland : WileyVCH Verlag GmbH & Co. - 9783527312719 - 3527312714 ; , s. 579-611
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Book chapter (other academic/artistic)abstract
- The field of semiconducting polymers has attracted many researchers from a diversity of disciplines. Printed circuitry, flexible electronics and displays are already migrating from laboratory successes to commercial applications, but even now fundamental knowledge is deficient concerning some of the basic phenomena that so markedly influence a device's usefulness and competitiveness. This two-volume handbook describes the various approaches to doped and undoped semiconducting polymers taken with the aim to provide vital understanding of how to control the properties of these fascinating organic materials. Prominent researchers from the fields of synthetic chemistry, physical chemistry, engineering, computational chemistry, theoretical physics, and applied physics cover all aspects from compounds to devices.Since the first edition was published in 2000, significant findings and successes have been achieved in the field, and especially handheld electronic gadgets have become billion-dollar markets that promise a fertile application ground for flexible, lighter and disposable alternatives to classic silicon circuitry. The second edition brings readers up-to-date on cutting edge research in this field.
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| 5. |
- Linares, Mathieu, et al.
(author)
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On the interface dipole at the pentacene-fullerene heterojunction : A theoretical study
- 2010
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In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:7, s. 3215-3224
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Journal article (peer-reviewed)abstract
- The electronic structure at organic/organic interfaces plays a key role, among others, in defining the quantum efficiency of organics-based photovoltaic cells. Here, we perform quantum-chemical and microelectrostatic calculations on molecular aggregates of various sizes and shapes to characterize the interfacial dipole moment at pentacene/C60 heterojunctions. The results show that the interfacial dipole mostly originates in polarization effects due to the asymmetry in the multipolar expansion of the electronic density distribution between the interacting molecules, rather than in a charge transfer from donor to acceptor. The local dipole is found to fluctuate in sign and magnitude over the interface and appears as a sensitive probe of the relative arrangements of the pentacene and C60 molecules (and of the resulting local electrical fields sensed by the molecular units).
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| 6. |
- Riffault, Sabine, et al.
(author)
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A Single Shot Pre-fusion-Stabilized Bovine RSV F Vaccine is Safe and Effective in Newborn Calves with Maternally Derived Antibodies
- 2020
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In: Vaccines. - : MDPI. - 2076-393X. ; 8:2
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Journal article (peer-reviewed)abstract
- Achieving safe and protective vaccination against respiratory syncytial virus (RSV) in infants and in calves has proven a challenging task. The design of recombinant antigens with a conformation close to their native form in virus particles is a major breakthrough. We compared two subunit vaccines, the bovine RSV (BRSV) pre-fusion F (preF) alone or with nanorings formed by the RSV nucleoprotein (preF+N). PreF and N proteins are potent antigenic targets for neutralizing antibodies and T cell responses, respectively. To tackle the challenges of neonatal immunization, three groups of six one-month-old calves with maternally derived serum antibodies (MDA) to BRSV received a single intramuscular injection of PreF, preF+N with Montanide (TM) ISA61 VG (ISA61) as adjuvant or only ISA61 (control). One month later, all calves were challenged with BRSV and monitored for virus replication in the upper respiratory tract and for clinical signs of disease over one week, and then post-mortem examinations of their lungs were performed. Both preF and preF+N vaccines afforded safe, clinical, and virological protection against BRSV, with little difference between the two subunit vaccines. Analysis of immune parameters pointed to neutralizing antibodies and antibodies to preF as being significant correlates of protection. Thus, a single shot vaccination with preF appears sufficient to reduce the burden of BRSV disease in calves with MDA.
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| 7. |
- Valarcher, Jean-Francois, et al.
(author)
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Single-Shot Vaccines against Bovine Respiratory Syncytial Virus (BRSV) : Comparative Evaluation of Long-Term Protection after Immunization in the Presence of BRSV-Specific Maternal Antibodies
- 2021
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In: Vaccines. - : MDPI. - 2076-393X. ; 9:3
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Journal article (peer-reviewed)abstract
- The induction of long-lasting clinical and virological protection is needed for a successful vaccination program against the bovine respiratory syncytial virus (BRSV). In this study, calves with BRSV-specific maternally derived antibodies were vaccinated once, either with (i) a BRSV pre-fusion protein (PreF) and Montanide(TM) ISA61 VG (ISA61, n = 6), (ii) BRSV lacking the SH gene (Delta SHrBRSV, n = 6), (iii) a commercial vaccine (CV, n = 6), or were injected with ISA61 alone (n = 6). All calves were challenged with BRSV 92 days later and were euthanized 13 days post-infection. Based on clinical, pathological, and proteomic data, all vaccines appeared safe. Compared to the controls, PreF induced the most significant clinical and virological protection post-challenge, followed by Delta SHrBRSV and CV, whereas the protection of PreF-vaccinated calves was correlated with BRSV-specific serum immunoglobulin (Ig)G antibody responses 84 days post-vaccination, and the IgG antibody titers of Delta SHrBRSV- and CV-vaccinated calves did not differ from the controls on this day. Nevertheless, strong anamnestic BRSV- and PreF-specific IgG responses occurred in calves vaccinated with either of the vaccines, following a BRSV challenge. In conclusion, PreF and Delta SHrBRSV are two efficient one-shot candidate vaccines. By inducing a protection for at least three months, they could potentially improve the control of BRSV in calves.
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| 8. |
- Van Regemorter, Tanguy, et al.
(author)
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Electronic Structure of Self-Assembled Monolayers on ZnO Surfaces
- 2011
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Conference paper (other academic/artistic)abstract
- Controlling the electronic properties at the interface between organic and inorganic materials is an issue of high interest since it is known to strongly affect the charge injection and the overall efficiency of opto-electronic devices. Self-assembled monolayers (SAMs) can be used to change the electronic properties of the underlying inorganic material and optimize the charge injection occurring at the interface. In this context, we aim here at a fundamental understanding of the electronic processes taking place when SAMs are deposited on ZnO. In particular, our theoretical investigations focus on the origin of the shift in the conduction band upon addition of SAMs on the ZnO surface. Calculations were performed within the framework of density functional theory (DFT) using periodic boundary conditions. The SAMs investigated here are 4-tertbutylpyridine (SAM1) and benzoic acid (SAM2), this latter with three different terminations. We show how the conduction band varies in the presence of SAMs on both polar and non-polar ZnO surfaces, in comparison to the bare surface. We find a shift in opposite direction for SAM1 and SAM2 for both surface orientations. A charge density analysis has been performed to identify the role of the surface orientation, bond dipole and dipole moment of the individual molecules in the observed effect. These theoretical observations have been confronted to preliminary experimental data for ZnO nano-particles with and without SAMs.
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