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Thiophene
Terms modified by Thiophene Selected AbstractsThiophene,Benzothiadiazole Co-Oligomers: Synthesis, Optoelectronic Properties, Electrical Characterization, and Thin-Film PatterningADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Manuela Melucci Abstract Newly synthesized thiophene (T) and benzothiadiazole (B) co-oligomers of different size, alternation motifs, and alkyl substitution types are reported. Combined spectroscopic data, electrochemical analysis, and theoretical calculations show that the insertion of a single electron-deficient B unit into the aromatic backbone strongly affects the LUMO energy level. The insertion of additional B units has only a minor effect on the electronic properties. Cast films of oligomers with two alternated B rings (B,T,B inner core) display crystalline order. Bottom-contact FETs based on films cast on bare SiO2 show hole-charge mobilities of 1,×,10,3,5,×,10,3,cm2 V,1s,1 and Ion/Ioff ratios of 105,106. Solution-cast films of cyclohexyl-substituted compounds are amorphous and do not show FET behavior. However, the lack of order observed in these films can be overcome by nanorubbing and unconventional wet lithography, which allow for fine control of structural order in thin deposits. [source] V-Shaped Thiophene-Based Oligomers with Improved Electroluminescence Properties,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2005G. Barbarella Abstract The synthesis via the Stille coupling of a new family of oligomers derived from benzo[b]thiophene is reported. Owing to their branched molecular structure lacking any symmetry element, these compounds display a low tendency to crystallization and better film-forming properties than their linear counterparts. Spin-coated films show photoluminescence efficiencies up to 50,%. Light-emitting diodes with spin-coated films as the active layers display markedly improved performance with respect to similar devices based on linear oligothiophenes, with luminance values up to more than 10,000,cd,m,2. Semiempirical PM3 and ZINDO/S calculations provide insight into the molecular geometries and electron distribution of the frontier orbitals of the new compounds. Cyclic voltammetry data indicates that the transformation of the thienyl sulfur of benzo[b]thiophene to the corresponding thienyl- S,S -dioxide leads an increase in electron affinity by 0.5,0.7,V, analogous to that of the corresponding linear oligomers. [source] Synthesis of 2,3-dihydro-1,3,4-thiadiazole, thiazole, and triazolo[4,3- a]pyrimidine derivatives from ethyl benzoylacetateHETEROATOM CHEMISTRY, Issue 2 2004Nora M. Rateb Thiophene and thiazole derivatives can be obtained from potassium salt of ethyl 3-oxo-3-phenyl-2-[(phenylamino)thioxomethyl]propanoate and ethyl chloroacetate in N,N -dimethylformamide solution under different conditions. 2,3-Dihydro-1,3,4-thiadiazoles and triazolo[4,3- a]pyrimidine were obtained from reaction of hydrazonoyl halides with each of thioanilide and pyrimidine-2-thione, respectively. Structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, spectral data, and alternative synthesis route whenever possible. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:107,113, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10222 [source] High Carrier Mobility up to 0.1,cm2,V,1,s,1 at Ambient Temperatures in Thiophene-Based Smectic Liquid Crystals,ADVANCED MATERIALS, Issue 5 2005M. Funahashi The synthesis and carrier-transport properties of oligothiophene liquid-crystalline semiconductors are reported. An asymmetrically substituted terthiophene and quaterthiophene give rise to a highly ordered smectic mesophase (see Figure) with an excellent carrier mobility of up to 0.1, cm2,V,1,s,1 over a wide mesophase temperature range, including ambient temperatures. This mobility is comparable to that of organic polycrystals. [source] Deep desulfurization of transportation fuels by characteristic reaction resided in adsorbentsAICHE JOURNAL, Issue 7 2009Sheng-Qiang Wang Abstract A method for deep desulfurization of transportation fuels was presented. Reactive conversion of sulfur compounds and the following adsorption occurred inside adsorbents. The condensation reaction with formaldehyde catalyzed by phosphomolybdic acid was shown effective for the removal of thiophenic and benzothiophenic compounds. Thiophene or benzothiophene of model fuels was completely removed. Coupling with an oxidation reaction, the total sulfur content of commercial fuels was dropped to below 15 ppm. Appropriate desulfur condition was at 70,80°C and ambient pressure without consumption of hydrogen. Saturated adsorbent was regenerated with heating in air at 400°C, and the sulfur capacity was almost fully recovered. Fuel quality was not negatively affected by the desulfur operation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Thiophene,phenylene/naphthalene-based step-ladder copolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2008Torsten W. Bünnagel Abstract A series of step-ladder copolymers based on thiophene,phenylene,thiophene SL1 - SL3 and thiophene,naphthylene,thiophene SL4 repeat units with varying lengths of the oligothiophene segment has been designed and synthesized via a microwave-assisted Stille-type cross-coupling reaction followed by a polymer-analogous cyclization reaction. The optical properties of the step-ladder copolymers have been investigated in detail, in particular at low temperature and in the solid-state. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7342,7353, 2008 [source] Low Bandgap Polymers by Copolymerization of Thiophene with BenzothiadiazoleMACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2009Youjun He Abstract Three low bandgap copolymers of thiophene and benzothiadiazole with electron-donating and electron-withdrawing substituents, P1, P2, and P3, have been synthesized by Pd-catalyzed Stille-coupling. Electronic energy levels of the polymers are estimated by cyclic voltammetry. The polymer films show a broad absorption band in the wavelength range from 300 to 750 nm. Among the polymers, the polymer that contains the 5,6-dinitrobenzothiadiazole unit, P3, possesses the smallest bandgap of 1.55 eV calculated from its absorption band-edge at ,800 nm. With the increase of the electron-withdrawing ability of the substituents on the benzothiadiazole unit, the energy bandgap of the polymers decreased in the order P1,>,P2,>,P3. The results indicate that stronger electron-withdrawing substituents on the acceptor unit can effectively decrease the bandgap of the polymers. [source] Geometries and Electronic Structures of Co-Oligomers and Co-Polymers Based on Tricyclic Nonclassical Thiophene: A Theoretical StudyMACROMOLECULAR THEORY AND SIMULATIONS, Issue 7-8 2008Yangwu Fu Abstract The geometries and electronic properties of four copolymers based on tricyclic nonclassical thiophene were studied using DFT at the B3LYP/6-31G(d) level. Bond lengths and their alternation, electron densities at BCPs, NICS, and WBIs were analyzed and correlated with the energy gap. The results show that the degree of conjugation increases upon main chain extension. The energy gap decreased steadily with increasing degree of polymerization. Conjugation is stronger in the central than in the outer section. The results suggest that the narrow HOMO/LUMO separation of tricyclic nonclassical thiophenes can be carried over to their co-polymers by using them as building blocks for the co-polymers. [source] Thiophene-based ionic liquids: synthesis, physical properties, self-assembly, and oxidative polymerization,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2008Christopher T. Burns Abstract Preparation and polymerization of methylimidazolium-based ionic liquids (ILs) that incorporate a thiophene moiety at the terminus of a C10 alkyl chain are described. Both a bromide and nitrate salt of the amphiphilic thiophene IL self-assembles in water (albeit the nitrate to a lesser extent), adopting columnar mesophases. Polarized optical microscopy and small-angle X-ray scattering (SAXS) studies show that at low water content the IL,water binary mixtures form liquid crystalline mesophases possessing significant short-range ordering due to strong , interactions between adjacent thiophene moieties. At higher water content, the short-range ordering is lost, but long-range ordering persists up to ca. 45% (w/w) water. The chemical oxidative coupling of the nitrate monomer yields a highly water-soluble polymer. Electrochemical studies show that the polymer possesses a high oxidation potential (1.95,V) and thus, is resistant to chemical doping. In dilute aqueous solution, electronic absorption spectroscopy and X-ray scattering show the polymer adopts a random, coil-like conformational state. Slight improvement in the polymer conformation can be achieved by exchange of the counter anion. Copyright © 2008 John Wiley & Sons, Ltd. [source] A Versatile Palladium/Triphosphane System for Direct Arylation of Heteroarenes with Chloroarenes at Low Catalyst Loading,ANGEWANDTE CHEMIE, Issue 37 2010David Roy Ein luftbeständiger Palladiumkatalysator mit dreizähnigem Phosphanligand aryliert elektronenreiche wie elektronenarme mehrfach substituierte Furane (X=O), Thiophene (X=S) und Pyrrole (X=NR5) sowie Thiazole direkt unter C-H-Aktivierung mit Chlorarenen (siehe Schema; DMAc=N,N -Dimethylacetamid, TBAB=Tetra- n -butylammoniumbromid). [source] Handbook of Thiophene-Based Materials.ANGEWANDTE CHEMIE, Issue 11 2010Applications in Organic Electronics, Photonics. John Wiley & Sons, Hoboken 2009. 910,S., geb., 339.00,,.,ISBN 978-0470057322 [source] ChemInform Abstract: Chiral Spiroaminoborate Ester as a Highly Enantioselective and Efficient Catalyst for the Borane Reduction of Furyl, Thiophene, Chroman, and Thiochroman-Containing Ketones.CHEMINFORM, Issue 23 2010Viatcheslav Stepanenko Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A New Thiophene-Based Tripodal Ligand: Synthesis and Cation Binding Properties.CHEMINFORM, Issue 21 2007Ahmed Attayibat Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Reactions of Electron-Withdrawing Thiophene 1,1-Dioxides with Furans.CHEMINFORM, Issue 5 2007A Novel Reaction Pathway. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Novel and Facile Synthesis of Thiophene, Thiazole, 2H-Pyran-2-one Benzimidazo[1,2-a]pyridine and Pyridine Derivatives Containing Antipyrine Moiety.CHEMINFORM, Issue 51 2004F. M. A. El-Taweel Abstract For Abstract see ChemInform Abstract in Full Text. [source] Diels,Alder Reaction of Thiophene: Dramatic Effects of High-Pressure/Solvent-Free Conditions.CHEMINFORM, Issue 30 2004Koji Kumamoto Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis and COX-2 Inhibitory Properties of N-Phenyl- and N-Benzyl-Substituted Amides of 2-(4-Methylsulfonylphenyl)cyclopent-1-ene-1-carboxylic Acid and of Their Pyrazole, Thiophene and Isoxazole Analogues.CHEMINFORM, Issue 22 2004Simona Rapposelli Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Catalytic Hydrogenation of Thiophene to Thiolane in the Gas Phase.CHEMINFORM, Issue 14 2002A. V. Mashkina Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Syntheses and Structures of Sulfilimine, Sulfone Diimine, and Sulfoximine Derivatives of a Monocyclic Thiophene, 3,4-Di-tert-butylthiophene.CHEMINFORM, Issue 44 2001Juzo Nakayama Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Conjugated Thiophene-Based Rotaxane: Synthesis, Spectroscopy, and ModelingCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2010Leszek Zalewski Dr. Abstract A dithiophene rotaxane 1,,-CD and its shape-persistent corresponding dumbbell 1 were synthesized and fully characterized. 2D NOESY experiments, supported by molecular dynamics calculations, revealed a very mobile macrocycle (,-CD). Steady-state and time-resolved photoluminescence experiments in solution were employed to elucidate the excited-state dynamics for both systems and to explore the effect of cyclodextrin encapsulation. The photoluminescence (PL) spectrum of 1,,-CD was found to be blueshifted with respect to the dumbbell 1 (2.81 and 2.78,eV, respectively). Additionally, in contrast to previous observations, neither PL spectra nor the decay kinetics of both threaded and unthreaded systems showed changes upon increasing the concentration or changing the polarity of the solutions, thereby providing evidence for a lack of tendency toward aggregation of the unthreaded backbone. [source] Contact sensitization from Compositae-containing herbal remedies and cosmeticsCONTACT DERMATITIS, Issue 4 2002Evy Paulsen The Compositae (Asteraceae) family of plants is currently an important cause of allergic plant contact dermatitis in Europe. The family comprises some of the oldest and most valued medicinal plants, and the increasing popularity of herbal medicine and cosmetics may theoretically result in a growing number of Compositae sensitizations from these sources. According to the literature at least 15 species, including among others arnica (Arnica montana), German and Roman chamomile (Chamomilla recutita and Chamaemelum nobile), marigold (Calendula officinalis), Echinacea and elecampane (Inula helenium), have been suspected of sensitization or elicitation of Compositae dermatitis. Epidemiological data are available for 2 species only, arnica and German chamomile, the rest of the evidence being anecdotal. Based on this, sensitization seems to occur relatively frequently with a few species such as arnica and elecampane, and occurs rarely with the majority, especially the widely used German chamomile. Sesquiterpene lactones are the most important allergens, but there are a few cases of sensitization from a coumarin, a sesquiterpene alcohol and a thiophene. The risk of elicitation of dermatitis by using Compositae-containing products in Compositae-sensitive individuals is by-and-large unknown. [source] Synthesis, analgesic, anti-inflammatory and ulcerogenic index activities of novel 2-methylthio-3-substituted-5,6-dimethyl thieno [2,3- d] pyrimidin-4(3H)-onesDRUG DEVELOPMENT RESEARCH, Issue 3 2007V. Alagarsamy Abstract A variety of novel 2-methylthio-3-substituted amino-5,6-dimethyl thieno [2,3- d] pyrimidin-4(3H)-ones were synthesized by reacting 3-amino-2-methylthio-5,6-dimethyl thieno [2,3- d] pyrimidin-4(3H)-one with different aldehydes and ketones. The starting material 3-amino-2-methylthio-5,6-dimethyl thieno [2,3- d] pyrimidin-4(3H)-one was synthesized from 2-amino-3-carbethoxy-4,5-dimethyl thiophene. The compounds were investigated for their analgesic activity in albino mice, and for their anti-inflammatory and ulcerogenic index activities in Wistar rats. The compound 2-(1-ethylpropylideneamino)-2-methylthio-5,6-dimethyl thieno [2,3- d] pyrimidin-4(3H)-one (AS2) showed the most potent analgesic activity of the series. It also showed more potent anti-inflammatory activity when compared to the reference standard, diclofenac sodium. The test compounds showed only mild ulcerogenic potential when compared to aspirin. Drug Dev Res 68:134,142, 2007. © 2007 Wiley-Liss, Inc. [source] Nitrate-Selective Solid Contact Electrodes with Poly(3-octylthiophene) and Poly(aniline) as Ion-to-Electron Transducers Buffered with Electron-Ion-Exchanging ResinELECTROANALYSIS, Issue 13-14 2006Galina Abstract The study of nitrate selective solid contact electrodes containing poly(3-octyl)thiophene and poly(aniline) demonstrated the advantage of buffering the transducing layer with electron-ion-exchanging resin. The buffering, in particular in the case of poly(aniline) doped with nitrate anions ensured significant improvement of the long-term stability and piece-to-piece reproducibility of the electrode potentials. It is shown that the redox species causes potential drift after a long time delay, probably because of slow diffusion in the membrane bulk. [source] Efficient Routes to Acenaphthylene-Fused Polycyclic Arenes/Heteroarenes and Heterocyclic Fluoranthene AnaloguesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2005Kausik Panda Abstract The acenaphthenone-derived , -oxoketene dithioacetal 2 has been subjected to various [3 + 3] aromatic and heteroaromatic annulation and other heterocyclization reactions previously developed in our laboratory, providing short and efficient routes to a diverse range of known and unknown acenaphtho-annulated linear and angular PAHs, heteroaromatics and five-membered heterocycles in good yields. Thus, benzo- and naphthoannulation of 2 with various allyl and benzyl Grignard reagents afforded substituted fluoranthenes 4a,c and benzo[k]fluoranthene 8, respectively, in good yields. Similarly, the parent benzo[j]fluoranthene 15a and its substituted derivative 16b have been synthesized by base-induced conjugate 1,4-addition of arylacetonitriles to 2, followed by acid-induced cyclization of the conjugate adducts 12a,b to give 13a,b and subsequent further transformations. The adducts obtained by 1,4-addition of anions derived from acetophenone and acenaphthenone were subjected toheterocyclization in the presence of ammonium acetate to give 8-arylacenaphtho[1,2- b]pyridines 18a,b and bis(acenaphtho)-annulated pyridine 20. Heterocyclization of 2 with bifunctional nucleophiles such as 2-picolyllithium and guanidinium nitrate afforded the corresponding acenaphtho[1,2- b]quinolizinium salt 23 and acenaphtho[1,2- d]pyrimidine 24, respectively, in high yields. Finally, acenaphtho[1,2- c]-fused five-membered heterocycles such as 7-(methylthio)acenaphtho[1,2- c]thiophene (25), 7-(methylthio)acenaphtho[1,2- c]furan (27) and 7-(methylthio)acenaphtho[1,2- c]pyrrole-2-carboxylic acid (30) were obtained in good yields by subjection of 2 to Simmons,Smith reaction conditions or by treatment with dimethylsulfonium methylide or glycinate dianion. Some of these newly synthesized PAHs or fused heterocycles were subjected to Raney Ni desulfurization to furnish sulfur-free compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Palladium-Catalysed Amination of Electron-Deficient or Relatively Electron-Rich Benzo[b]thienyl Bromides , Preliminary Studies of Antimicrobial Activity and SARsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2004Maria-João R. P. Queiroz Abstract Several diarylamines in the benzo[b]thiophene series were prepared in good to high yields by palladium-catalysed amination of ethyl 3-bromobenzo[b]thiophene-2-carboxylate with anilines and 5-aminoindole in the presence of Pd(OAc)2, BINAP and Cs2CO3 in toluene. The presence of the ester group at the 2-position of the benzo[b]thiophene moiety increases the yields and lowers the heating times relative to the reactions performed with 3-bromobenzo[b]thiophene. When aminopyridines were used instead of anilines, the ligand and the solvent need to be changed to XANTHPHOS and dioxane in the amination reaction. With 2-aminopyridine a one-pot C,N coupling and intramolecular cyclization involving the nitrogen atom of the pyridine ring occurred, with loss of ethanol, giving an interesting fluorescent tetracyclic heteroaromatic compound. The antimicrobial activity, the minimal inhibitory concentrations (MICs) and the structure-activity relationships (SARs) were evaluated. A selectivity with low MICs was observed against Bacillus Cereus, and good results were also obtained against Candida albicans. The acids obtained by hydrolysis of the ester group, as non-proteinogenic ,,,-unsaturated ,-amino acids, can be incorporated into peptide chains to induce conformational constraints. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Aligning Single-Walled Carbon Nanotubes By Means Of Langmuir,Blodgett Film Deposition: Optical, Morphological, and Photo-electrochemical StudiesADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Gabriele Giancane Abstract An alkoxy-substituted poly(phenylene thiophene) is used in order to suspend single-walled carbon nanotubes in an organic solvent. The suspension is spread on the air,water interface of a Langmuir trough and the floating film is characterized by means of Brewster angle microscopy and UV-visible reflection spectroscopy and the compression isotherm is recorded. The polymer/carbon-nanotube blend is transferred onto different substrates using the Langmuir,Blodgett technique. AFM measurements indicate the formation of globular structures for the samples transferred at low surface-pressure values and a tubular morphology for high-pressure-deposited samples. AFM analysis is repeated on a sample exposed to soft X-rays for about 5,h and a highly organized structure of bundles of carbon nanotubes rises up. Samples with different numbers of layers are transferred onto ITO substrates by means of the Langmuir,Blodgett method and are tested as photocathodes in a photo-electrochemical cell. A Voc of 0.18,V, an Isc of 85.8,mA, FF of 40.0%, and , of (6.23,×,10,3)% are obtained. [source] Novel polyketides synthesized with a higher plant stilbene synthaseFEBS JOURNAL, Issue 13 2001Hiroyuki Morita The physiological function of the stilbene synthase (STS) from groundnut (Arachis hypogaea) is the formation of resveratrol. The enzyme uses 4-coumaroyl-CoA, performs three condensations with malonyl-CoA, and folds the resulting tetraketide into a new aromatic ring system. We investigated the capacity for building novel and unusual polyketides from alternative substrates. Three types of products were obtained: (a) complete reaction (stilbene-type), (b) three condensations without formation of an aromatic ring (CTAL-type pyrone derailment), and (c) two condensations (BNY-type pyrone derailment). All product types were obtained from 4-fluorocinnamoyl-CoA and analogs in which the coumaroyl moiety was replaced by furan or thiophene. Only type (b) and (c) products were synthesized from other 4-substituted 4-coumaroyl-CoA analogs (-Cl, -Br, -OCH3). Benzoyl-CoA, phenylacetyl-CoA, and medium chain aliphatic CoA esters were poor substrates, and the majority of the products were of type (c). The results show that minor modifications can be used to direct the enzyme reaction to form a variety of different and new products. Manipulation of the biosynthesis of polyketides by synthetic analogs could lead to the development of a chemical library of pharmaceutically interesting novel polyketides. [source] High-Performance Phototransistors Based on Organic Microribbons Prepared by a Solution Self-Assembly ProcessADVANCED FUNCTIONAL MATERIALS, Issue 6 2010Yunlong Guo Abstract Oligoarenes as an alternative group of promising semiconductors in organic optoelectronics have attracted much attention. However, high-performance and low-cost opto-electrical devices based on linear asymmetric oligoarenes with nano/microstructures are still rarely studied because of difficulties both in synthesis and high-quality nano/microstructure growth. Here, a novel linear asymmetric oligoarene 6-methyl-anthra[2,3- b]benzo[d]thiophene (Me-ABT) is synthesized and its high-quality microribbons are grown by a solution process. The solution of Me-ABT exhibits a moderate fluorescence quantum yield of 0.34, while the microribbons show a glaucous light emission. Phototransistors based on an individual Me-ABT microribbon prepared by a solution-phase self-assembly process showed a high mobility of 1.66,cm2,V,1 s,1, a large photoresponsivity of 12,000 A W,1, and a photocurrent/dark-current ratio of 6000 even under low light power conditions (30,µW cm,2). The measured photoresponsivity of the devices is much higher than that of inorganic single-crystal silicon thin film transistors. These studies should boost the development of the organic semiconductors with high-quality microstructures for potential application in organic optoelectronics. [source] Thiophene,Benzothiadiazole Co-Oligomers: Synthesis, Optoelectronic Properties, Electrical Characterization, and Thin-Film PatterningADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Manuela Melucci Abstract Newly synthesized thiophene (T) and benzothiadiazole (B) co-oligomers of different size, alternation motifs, and alkyl substitution types are reported. Combined spectroscopic data, electrochemical analysis, and theoretical calculations show that the insertion of a single electron-deficient B unit into the aromatic backbone strongly affects the LUMO energy level. The insertion of additional B units has only a minor effect on the electronic properties. Cast films of oligomers with two alternated B rings (B,T,B inner core) display crystalline order. Bottom-contact FETs based on films cast on bare SiO2 show hole-charge mobilities of 1,×,10,3,5,×,10,3,cm2 V,1s,1 and Ion/Ioff ratios of 105,106. Solution-cast films of cyclohexyl-substituted compounds are amorphous and do not show FET behavior. However, the lack of order observed in these films can be overcome by nanorubbing and unconventional wet lithography, which allow for fine control of structural order in thin deposits. [source] Photocrosslinkable Polythiophenes for Efficient, Thermally Stable, Organic PhotovoltaicsADVANCED FUNCTIONAL MATERIALS, Issue 14 2009Bumjoon J. Kim Abstract Photocrosslinkable bromine-functionalized poly(3-hexylthiophene) (P3HT-Br) copolymers designed for application in solution-processed organic photovoltaics are prepared by copolymerization of 2-bromo-3-(6-bromohexyl) thiophene and 2-bromo-3-hexylthiophene. The monomer ratio is carefully controlled to achieve a UV photocrosslinkable layer while retaining the ,,, stacking feature of the conjugated polymers. The new materials are used as electron donors in both bulk heterojunction (BHJ) and bilayer type photovoltaic devices. Unlike devices prepared from either P3HT:PCBM blend or P3HT-Br:PCBM blend without UV treatment, photocrosslinked P3HT-Br:PCBM devices are stable even when annealed for two days at the elevated temperature of 150,°C as the nanophase separated morphology of the bulk heterojunction is stabilized as confirmed by optical microscopy and grazing incidence wide angle X-ray scattering (GIWAXS). When applied to solution-processed bilayer devices, the photocrosslinkable materials show high power conversion efficiencies (,2%) and excellent thermal stability (3 days at 150,°C). Such performance, one of the highest obtained for a bilayer device fabricated by solution processing, is achieved as crosslinking does not disturb the ,,, stacking of the polymer as confirmed by GIWAXS measurements. These novel photocrosslinkable materials provide ready access to efficient bilayer devices thus enabling the fundamental study of photophysical characteristics, charge generation, and transport across a well-defined interface. [source] | |||||||||||||||||||||||||||||||