Showing papers by "Jean Roncali published in 2008"
TL;DR: An amorphous photoluminescent material based on a dithienylbenzothiadiazole structure has been used for the fabrication of organic red-light-emitting diodes as discussed by the authors.
Abstract: An amorphous photoluminescent material based on a dithienylbenzothiadiazole structure has been used for the fabrication of organic red-light-emitting diodes. The synergistic effects of the electron-transport ability and exciton confinement of the emitting material allow for the fabrication of efficient pure-red-light-emitting devices without a hole blocker.
48 citations
TL;DR: In this paper, a series of push-pull chromophores built around dithienylethylene-based π-conjugating spacers have been investigated by UV-vis, IR, and Raman spectroscopies and electric field-induced second harmonic generation (EFISH) measurements.
Abstract: The vibrational, optical, and nonlinear optical (NLO) properties of a series of push−pull chromophores built around dithienylethylene-based π-conjugating spacers have been investigated by UV−vis, IR, and Raman spectroscopies and electric field-induced second harmonic generation (EFISH) measurements. The effects of the strength of the acceptor group on the molecular electronic properties of these conjugated NLO chromophores have been addressed. The magnitude of the intramolecular charge transfer has been tested as a function of the acceptor strength and of the bridging of the spacer. Density functional theory (DFT) calculations have been performed to help the assignment of the main electronic and vibrational features of the NLO chromophores and to derive useful information about their molecular structures. EFISH measurements show that push−pull systems that contain strong electron-acceptor groups connected via a rigidified dithienylene spacer exhibit large values of μβ0. Theoretical NLO calculations are in...
46 citations
TL;DR: In this paper, hybrid conjugated systems consisting of a triphenylamine core substituted by three dithiafulvenyl moieties have been synthesized and tested as active materials in organic field-effect transistors and photovoltaic devices.
46 citations
TL;DR: Asymmetrically 9,10-disubstituted anthracene derivatives 1a/1b have been synthesized and characterized as discussed by the authors, which exhibit a high solubility and can be easily purified by chromatographic methods.
34 citations
TL;DR: In this article, self-assembled monolayers (SAMs) of a conjugated bithiophenic system connected to an alkanethiol chain have been deposited on gold surface.
Abstract: Self-assembled monolayers (SAMs) of a conjugated bithiophenic system connected to an alkanethiol chain have been deposited on gold surface. The electroactive bithiophenic system involves a 3,4-ethylenedioxythiophene (EDOT) unit and a thiophene ring on which an alkanethiol is attached at the internal β-position via a sulfide linkage. The analysis of the structure of the SAMs by IR spectroscopy, ellipsometry, contact angle measurement and X-ray photoelectron spectroscopy (XPS) provides consistent results indicating compact monolayers in which the alkyl linkers are arranged in an almost vertical fashion while the bithiophenic-conjugated systems are essentially parallel to the surface. Cyclic voltammetry shows that application of a few potential scans to SAMs immersed in a medium containing only a supporting electrolyte leads to the typical electropolymerization curves while the CV of the electrooxized monolayer exhibits a reversible cyclic voltammogram characteristic of a stable electroactive extended conjugated system. The characterization of the electropolymerized monolayers by IR spectroscopy, ellipsometry, contact angle measurement, and XPS indicates compact monolayers. The analysis of the current voltage characteristics of the monolayers by conducting AFM before and after electrooxidation shows that the enhancement of the effective conjugation resulting from electropolymerization leads to a significant increase of the transport properties.
32 citations
TL;DR: Bithiophene associating 3,4-ethylenedioxythiophene and 3,bromothiophene, and the corresponding polymer exhibit self-rigidified structures of the conjugated backbones resulting from the association of S −Br and S −O non-bonded intramolecular interactions as mentioned in this paper.
Abstract: Bithiophene associating 3,4-ethylenedioxythiophene and 3-bromothiophene, and the corresponding polymer exhibit self-rigidified structures of the conjugated backbones resulting from the association of S–Br and S–O non-bonded intramolecular interactions.
29 citations
TL;DR: A new ferrocenyl bithiophenic polymer has enabled the first demonstration of internally referenced quantitative analysis of charge-transfer reactions, which may enable better understanding and applications of conducting polymers in e.g. supercapacitors.
28 citations
TL;DR: A 3D π-conjugated system obtained by grafting 3,4-ethylenedioxythiophene (EDOT) on a twisted bithiophene core has been synthesized and used as precursor for electropolymerization as mentioned in this paper.
27 citations
TL;DR: In this paper, the metal cations with linear or macrocyclic polyether functional groups lead to modifications of the electronic properties of the π-conjugated backbone through various mechanisms including direct electronic effects on a single conjugated chain, collective electrochemical processes, or conformational changes.
Abstract: The association of linear or macrocyclic polyethers with the electronic properties of the π-conjugated polythiophene backbone leads to functional conducting polymers that exhibit metal cation dependent electronic properties. Based on this concept, various classes of cation sensors have been proposed and investigated for almost two decades. The interactions of metal cations with linear or macrocyclic polyether functional groups lead to modifications of the electronic properties of the π-conjugated backbone through various mechanisms including direct electronic effects on a single conjugated chain, collective electrochemical processes, or conformational changes. Conjugated polymers and oligomers representative of these various processes are discussed with an emphasis on recent examples of derivatized conjugated systems in which the interactions between metal cations and polyether groups serve as driving force to create molecular motion in conjugated systems.
14 citations
TL;DR: Investigation of quaterthiophenes bearing one (1) or two (2) alkanethiol chains attached at the internal beta-position of the outermost thiophene ring through a sulfide linkage indicates that introduction of two thiol groups in the structure leads to double fixation of the oligothiophene chain.
Abstract: Quaterthiophenes bearing one (1) or two (2) alkanethiol chains attached at the internal β-position of the outermost thiophene ring through a sulfide linkage have been synthesized. Cyclic voltammetric analysis of their electrochemical behavior in solution suggests that electrooxidation of the doubly substituted oligomer 2 leads to electrodeposition of a poly(disulfide) on the anode surface. Monolayers of 1 Introduction or 2 on gold surfaces have been investigated and characterized by cyclic voltammetry, ellipsometry, contact angle measurement, and X-ray photoelectron spectroscopy. The results of these investigations indicate that introduction of two thiol groups in the structure leads to double fixation of the oligothiophene chain with the main axis of the conjugated system oriented parallel to the surface. The effects of single versus double fixation of the quaterthiophene chain on the electrochemical properties and stability of the corresponding monolayers are discussed.
13 citations
TL;DR: 3D-conjugated systems based on oligothiophene segments grafted on a phosphorus or on a phosphine oxide node have been synthesized under Stille coupling conditions.
Abstract: 3D-conjugated systems based on oligothiophene segments grafted on a phosphorus or on a phosphine oxide node have been synthesized. Under Stille coupling conditions, bromide terminated thienyl phosphine derivatives undergo a breaking of the phosphorus–carbon bond attributed to a ligand exchange with the Pd catalyst. The electronic properties of the new compounds have been analyzed by UV-vis and fluorescence spectroscopy and cyclic voltammetry.
TL;DR: In this article, organic field effect transistors (OFETs) based on two π-conjugated oligomers derived from thiophenes were used as sensors for the detection of 2,4-dinitrotoluene (DNT).