Anthracene- and thiophene-containing poly(p-arylene-ethynylene)/poly(p-arylene-vinylene)s: towards optimized structures for photovoltaic applications

Summary: Anthracene- and thiophene-containing PPE-PPV systems, bearing asymmetric alkoxy side chains, which are presumed to ensure optimal interfacial contact with PCBM([6,6]-phenyl C61 butyric acid methyl ester) in bulk heterojunction solar cells, have been synthesized and characterized. The polymers exhibit high molecular weights with polydispersity indices around 2. The effect of the position of the aromatic rings on their photophysical properties was found to be very pronounced in the case of the anthracene-containing polymers, but less significant in the case of the thiophene-containing counterparts

Effect of Styryl Side Groups on the Photophysical Properties and Hole Mobility of PPE-PPV Systems

This contribution reports on the synthesis of defect-free styryl-substituted poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene)s, DO- and MEH-ST-PPE2-PPV2, consisting of a 2:2 triple bond/double bond ratio in the main chain. A detailed and systematic comparison of their photophys. properties with those of solely alkoxy-substituted polymer O-8-PPE2-PPV2, highlighting the effect of the styryl side groups, has been carried out. The bis(styryl) substituents act on the one hand as electron donor to the main chain conjugation system and, on the other hand, form a sep. bis(styryl)phenylene chromophore system. The resulting two-dimensional and sep. conjugation construct in ST-PPE-PPV polymers is confirmed by the fluorescence excitation anisotropy curves, which reach the value 0 around 360 nm corresponding to the absorption of the bis(styryl) system. Thin film PL and EL spectra of MEH-ST-PPE2-PPV2 are red-shifted relative to DO-ST-PPE2-PPV2, due to strong .pi.-.pi. interchain interactions resulting from the grafting of methoxy side groups, potentially explaining the better EL performance of MEH- than DO-ST-PPE2-PPV2 LED device (glass substrate/ITO/PEDOT:PSS/ST-PPE2-PPV2/Ca/Ag) as well as the higher intrinsic hole mobility value, .mu.hole (measured using CELIV technique) for MEH- (2.8 10-6 cm2/Vs) than DO-ST-PPE2-PPV2 (1.5 10-6 cm2/Vs). Both values are, however, at least 2-fold lower than that of O-8-PPE2-PPV2 (5.5 10-6 cm2/Vs) due to the twist in their conjugated backbone caused by the styryl side groups. Nevertheless, nonoptimized bulk heterojunction solar cells of .eta.AM1.5 around 1% were readily designed using MEH-ST-PPE2-PPV2 as donor and PCBM as acceptor in a 1:3 wt. ratio

Effect of Styryl Side Groups on the Photophysical Properties and Hole Mobility of PPE-PPV Systems

This contribution reports on the synthesis of defect-free styryl-substituted poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene)s, DO- and MEH-ST-PPE2-PPV2, consisting of a 2:2 triple bond/double bond ratio in the main chain. A detailed and systematic comparison of their photophys. properties with those of solely alkoxy-substituted polymer O-8-PPE2-PPV2, highlighting the effect of the styryl side groups, has been carried out. The bis(styryl) substituents act on the one hand as electron donor to the main chain conjugation system and, on the other hand, form a sep. bis(styryl)phenylene chromophore system. The resulting two-dimensional and sep. conjugation construct in ST-PPE-PPV polymers is confirmed by the fluorescence excitation anisotropy curves, which reach the value 0 around 360 nm corresponding to the absorption of the bis(styryl) system. Thin film PL and EL spectra of MEH-ST-PPE2-PPV2 are red-shifted relative to DO-ST-PPE2-PPV2, due to strong .pi.-.pi. interchain interactions resulting from the grafting of methoxy side groups, potentially explaining the better EL performance of MEH- than DO-ST-PPE2-PPV2 LED device (glass substrate/ITO/PEDOT:PSS/ST-PPE2-PPV2/Ca/Ag) as well as the higher intrinsic hole mobility value, .mu.hole (measured using CELIV technique) for MEH- (2.8 10-6 cm2/Vs) than DO-ST-PPE2-PPV2 (1.5 10-6 cm2/Vs). Both values are, however, at least 2-fold lower than that of O-8-PPE2-PPV2 (5.5 10-6 cm2/Vs) due to the twist in their conjugated backbone caused by the styryl side groups. Nevertheless, nonoptimized bulk heterojunction solar cells of .eta.AM1.5 around 1% were readily designed using MEH-ST-PPE2-PPV2 as donor and PCBM as acceptor in a 1:3 wt. ratio

Photophysical properties of PPP and PPV derivatives bearing polystyrene or polycaprolactone as side groups

The photophys. properties were studied of poly(p-phenylene) (PPP) and poly(p-phenylene-vinylene) (PPV) derivs. laterally decorated with polystyrene (PPV-PSt) or poly(e-caprolactone) (PPP-PCL, PPP- alt PCL, PPV-PCL and PPV-PCL-Br). The polymers emit blue light and exhibit high relative and abs. photoluminescence quantum yield (Ff), in dil. soln., thin film (spin-coated and inkjet-printed), and bulk state. These parameters are ascribed to the side groups, which suppress the strong pi-pi interactions and, consequently, excimer formation. Lower Ff was obsd. for PPV-PCL-Br and its corresponding model compd. dibromo-distyrylbenzene Br2-DSB, which was ascribed to heavy atom effect enabling intersystem crossing from S1 to T1. However, studies at 77 K did not reveal phosphorescence; in contrast, an enhancement of the fluorescence intensity with respect to room temp. measurements was obsd

A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

Molecular probes are widely used tools in chemical biology that allow tracing of bioactive metabolites and selective labeling of proteins and other biomacromolecules. A common structural motif for such probes consists of a reporter that can be attached by copper(I)-catalyzed 1,2,3-triazole formation between terminal alkynes and azides to a reactive headgroup. Here we introduce the synthesis and application of the new thiazole-based, azide-tagged reporter 4-(3-azidopropoxy)-5-(4-bromophenyl)-2-(pyridin-2-yl) thiazole for fluorescence, UV and mass spectrometry (MS) detection. This small fluorescent reporter bears a bromine functionalization facilitating the automated data mining of electrospray ionization MS runs by monitoring for its characteristic isotope signature. We demonstrate the universal utility of the reporter for the detection of an alkyne-modified small molecule by LC-MS and for the visualization of a model protein by in-gel fluorescence. The novel probe advantageously compares with commercially available azide-modified fluorophores and a brominated one. The ease of synthesis, small size, stability, and the universal detection possibilities make it an ideal reporter for activity-based protein profiling and functional metabolic profiling

Anthracene- and thiophene-containing MEH-PPE-PPVs: Synthesis and study of the effect of the aromatic ring position on the photophysical and electrochemical properties

This contribution reports on the synthesis and characterization of thiophene- (P1, P2, and P3) and anthracene- (P4 and P5) containing PPE-PPV copolymers. The thermostable, soluble and film-forming polymers were fully characterized by NMR, IR and ELEM. ANAL.; they exhibit high molar masses with polydispersity indices below 2.5. The position of the thiophene in the polymeric backbone has insignificant influence on the spectroscopic properties of the polymers. In contrast, the anthracene-containing polymers reveal position dependent optical properties. A constant bathochromic shift of 50 nm was observed going from P4, where anthracene is surrounded by two double bonds, to P5, where anthracene is at the bridge between a triple bond and a double bond, as well as from P5 to P6 where anthracene is surrounded by two triple bonds. This correlates to the decrease of the observed anthracene band around 255 nm going from P4 through P5 to P6, amounting to the degree of contribution of the anthracene unit to the main chain conjugation. The phenomenon known as CN-PPV effect was observed in the case of P4 [?f (solution) = 3%, ?f (solid) = 13%]. Electrochemical studies carried out under absolute inert conditions revealed lower electrochemical band gap energies, Emath image, than Emath image

Effect of Side Chain Length Variation on the Optical Properties of PPE-PPV Hybrid Polymers

New 4-fold alkoxy-substituted poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene) polymers (PPE-PPV) have been synthesized in order to elucidate the previously observed effect of side chains on the thin film properties (i.e., color variation) of PPE-PPVs. The length of the side chains attached to the PPE segments, CnH2n+1, has been varied from n = 12 to 19. The side chains attached to the PPV segments have been kept fixed to C8H17. Polymers with n <16 are yellow in color, whereas those with n = 16 are orange. Differential scanning calorimetry and nanoindentation analyses reveal side chain crystallization above room temperature in samples with longer side chains (n = 16). Reorganization of the longer side chains attached to the PPE units seems to support stronger p-p overlap between the chain backbones. The red shift for n = 16 was confirmed by photoluminescence (PL) and electroluminescence (EL) spectra obtained for inkjet printed and spin-coated thin films. However, the obtained orange-red EL emission colors are unstable upon increase of the applied voltage. A blue shift of up to 100 nm was observed. All the polymers exhibited very high relative and absolute PL quantum yields in solution (~70%). Their solid-state absolute PL quantum yield was found to be between 10 and 20%. Polymeric light emitting diodes (PLED) with the following structure ITO//PEDOT:PSS//Pn/8//Ca//Ag were fabricated. The devices were fully characterized and showed low turn-on voltages

La prise en charge des troubles psychiques de l'adolescent par le psychiatre, le psychologue et le médecin généraliste

Le médecin généraliste forme avec le psychiatre un partenariat dans un système de prise en charge partagée. Ils ont un rôle complémentaire dans la prise en charge des troubles psychiques de l'adolescent. Les nouvelles conventions prétendent mettre en place une organisation des soins qui permettent un meilleur suivi médical du patient et un recours optimal aux soins spécialisés. La rencontre du médecin généraliste avec l'adolescent est assez fréquente et nécessite une approche et un abord spécifique et adéquat. Proche de la famille et du jeune le médecin généraliste est amené à jouer son rôle en respectant la confidentialité de celui-ci et en donnant à la famille la place nécessaire. Le psychiatre et le psychologue sont amenés à répondre à la demande croissante des adolescents en souffrance dans cette phase charnière de la constitution de leur personnalité où les limites entre le normal et le pathologique dans le comportement peuvent paraître floues. Devant la complexité de suivi de l'adolescent, ont peut être amené à se demander si les soins de santé mentale sont déjà partagés par les différents intervenants, et se poser des questions sur la difficulté d'accès aux soins en psychiatrie, sur les causes de manque de communication et de contact direct ou indirect entre le médecin traitant et le secteur de psychiatrie. Alors que le médecin traitant peut éprouver des difficultés dans la prise en charge de l'adolescent en souffrance psychique, difficultés liées à la complexité même de cet âge de la vie et à la prescription des psychotropes et des choix thérapeutiques. La formation initiale ou continue en psychiatrie des médecins généralistes n'est pas toujours adaptée à une bonne conduite à tenir. Pour rompre l'isolement des médecins généralistes face à leurs limites, le travail en réseau peut paraître comme solution. Une étude qualitative réalisée par des entretiens auprès de médecins généralistes, psychiatres, psychologues et adolescents suivis en psychiatrie a été réalisée pour répondre à ces questions. Elle montre que malgré les liens qui se tissent antre l'adolescent et son médecin traitant au fil de temps ce n'est pas lui qu'il choisit toujours pour parler de ses souffrances psychiques (crainte de rupture de confidentialité, liens de proximité avec tous les membres de la famille, doute sur ses compétences). Mais le médecin généraliste n'est pas pour autant contacté par le psychiatre ou le psychologue qui prennent en charge le patient. La coordination des soins, la communication entre médecins, l'échange d'information et le travail en réseau restent des supports de travail à développer dans une organisation qui prenne en compte cette évolution, qui ne soit pas sous qualifiante pour chaque intervenant avec une réflexion de l'utilisation des compétences en cherchant toujours à les perfectionner.PARIS7-Xavier Bichat (751182101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF