Preparation and properties of a new conducting polyheterocycle: Polydithieno [3, 4-b : 3′, 4′-d] thiophene (PDTT) (original) (raw)
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New low-gap thiophene-based regular copolymers are produced by anodic coupling of 3,4ethylenedioxythiophene-2,5-substituted thieno[3,4-b]pyrazine (TP), cyclopenta[2,1-b;3,4-b′]dithiophen-4-one (CO), and 4-dicyanomethylene-4H-cyclopenta[2,1-b;3,4-b′]dithiophene (CN). The copolymers are characterized by cyclic voltammetry, FTIR reflection-absorption and UV-vis spectroscopy, electrochemical quartz crystal microbalance analysis, and in situ pand n-conductivity measurement. The copolymers show low optical gaps (measured at the maximum absorption) and electrochemical gaps (measured from redox potentials) in the range 0.8-1.3 eV. The CN-based polymer displays the lowest reported electrochemical gap (0.8 V). Random copolymers of CO and 3,4-ethylenedioxythiophene (EDT) have also been produced and compared with the relevant regular copolymer. Copolymerization of CO with increasing amounts of EDT decreases the gap. From an analysis of redox potential as a function of EDT fraction, it is found that the gap is limited by the redox potentials of the individual homopolymers. Localization of n-doping carriers in the polythiophene chains is progressively increased by donor-acceptor alternation and then by copolymerization till the expected intrinsic conductivity is made completely p-type. Figure 9. Cyclic voltammograms of (a) poly(3-octylthiophene) and (b) poly(dithienylvinylene) in acetonitrile + 0.1 M Bu4NClO4. Scan rate: 0.1 V s -1 .
The routes towards processible and stable conducting poly(thiophene)s
Synthetic Metals, 1993
The underlying nature of the thermal instability of doped poly(3alkylthiophene)s, a fatal problem for their application, is discussed. The so-called "thermal undoping" is attributed to interactions due to steric hindrance of the long flexible side chains, which twist the conjugated main chain and kick out the dopants. Thus the routes to suppress thermal undoping are to avoid or alleviate the side chain interactions by separating the side chains from each other, or from the main chains, and also leaving space around the main chains to accommodate dopants. Accordingly, poly(3-(4-octylphenyl)thiophene), random copolymers of 3methylthiophene and 3-octylthiophene, and regular copolymers of thiophene and 3octylthiophene are prepared. Thermal undoping is significantly suppressed in these polymers. Some of these polymers are soluble and fusible in the neutral state. After doping they become highly conductive, yet remain stable even at elevated temperatures. Thermochromism, solvatochromism and thermal undoping are thus all related to side chain mobility.
Synthetic Metals, 1986
Passive, ultra-thin dielectric films (5-7 nm) of poly(phenylene oxide), PPO, are formed by the anodic electropolymerization of tetramethylammonium phenoxide from acetonitrile onto Pt or Au electrodes. These films can have exceptionally low permeabilities to solution redox species, depending on electrcpolymerization potential, the time of deposition, and cross-linking reactions. The latter becomes evident at +0.4 V vs. SSCE and in the presence of electrogenerated mediator-oxidant. PPO blocks the cyclic voltammetry of ferrocene carboxylic acid and Cl-oxidations in acetonitrile by > 99% and 922, respectively, and reduction of [Fe(CN)JM3 and oxidation of the sodium salt of ferrocene carboxylic acid in water by > 99%. By rotating disk voltammetry, the permeability PDs.poL of the film to FeCp,* in CH,CN is as low as 8 x lo-" cm2/s. Films prepared from alkyl substituted phenolates are thicker, more hydrophobic, but also more permeable owing to less efficient cross-linking. Film thicknesses were obtained by profilometry, ellipsometry, XPS, and high frequency electrical capacitance measurements, and physical and structural information by use of contact angle measurements and attenuated total reflectance FTIR.
Theoretical Treatment of 3-Phenylsubstituted Thiophenes and Their Intrinsically Conducting Polymers
ECS Transactions, 2007
A series of 3-(p-X-phenyl) thiophene monomers (X= -H, -CH3, - OCH3, -COOC2H5, -COCH3,-NO2) was electrochemically polym-erized to furnish polymer films that could be reversibly reduced and oxidized (n- and p-doped). The oxidation potentials of the monomers and formal potentials of the n- and p-doping processes of polymers were correlated with resonance and inductive effects of the substituents on the phenyl ring as well as the semiempirically calculated heats of formation of the monomer radical cations. Moreover, the oxidation potentials of the monomers were correlated with the ionization potentials of the monomers calculated using density functional theory. The reactivity for coupling reactions and the major regioselective products of the polymerization reaction of mono- and oligo-3- phenylthiophenes are inferred from the calculated lone electron spin densities of the respective radical cations. The ionization potentials, which correspond to the energies for generating radical catio...
Electrochromic properties of poly(diphenyldithieno[3,2-b;2′,3′-d]thiophene
Journal of Electroanalytical Chemistry, 2006
A conducting polymer of diphenyldithieno[3,2-b;2 0 ,3 0 -d]thiophene (DPhDTT) was synthesized via potentiodynamic method in dichloromethane (DCM)/acetonitrile (AN) (1:9 (v/v))-NaClO 4 /LiClO 4 (0.1:0.1 M) solvent-electrolyte couple. Characterizations of the resulting homopolymer were performed by cyclic voltammetry (CV), Fourier transform infrared (FTIR) and UV-Vis spectroscopy. Moreover, the spectroelectrochemical and electrochromic properties of the homopolymer films were investigated. Consequently, P(DPhDTT)/ PEDOT device was constructed and their characteristics were examined in detail. A potential range of 0.0-2.0 V was found to be suitable for operating the P(DPhDTT)/PEDOT device between yellow and blue colors. The device reveals good open circuit memory and stability.
Macromolecules
The synthesis, electrochemical and spectroscopic properties of a series of thiophene-substituted 1,3-dithiole-2-ones is described. The derivatives Th-3,3, Th-2,2, Th-2,3, Th-3,3(2,2′-Me), and Th3,3-(2,5,2′,5′-Me), have been successfully polymerized by cyclic voltammetry. From the UV−visible spectra of the neutral films, it was determined that PTh-3,3, PTh-2,2 and PTh-2,3 have a bandgap of 2.04, 2.30, and 2.18 eV, respectively. The voltammetric response of Th-3,3(2,2′-Me) was noticeably different from the other polymers. The SNIFTIRS data suggested that Th-3,3(2,2′-Me) was formed by bonding via the β-positions of the thiophene ring, resulting in a poorly conductive polymer. The in situ solid-state modification of PTh-3,3 to produce a new TTF-derivatized polythiophene was carried out. The cyclic voltammetry of the modified polymer confirmed the inclusion of TTF into the backbone of the film.
2004
Step towards the realisation of low-cost, allpolymer, flexible OFETs. Charge carrier mobilities comparable to that of amorphous silicon have been obtained. 15 As a demonstrator functional 15-bit programmable code generators are fabricated. generate the electronically excited-state molecule as well as development of new materials with high performance and judicious choice of the combination of emitting and charge transporting materials and the combination of emitting and luminescent dopant molecules, are of vital importance. For this purpose, not only emitting materials but also charge transporting materials are also required. Both polymers and small molecules are candidates for materials in OLEDs. Considering the fact that light-emitting films of plastic materials have been realised, there is also a chance to achieve photovoltaic conversion in such materials. 39 There is no short-term ambition to replace silicon, or thin film technologies (crystalline and amorphous silicon, copper indium diselenide) 40 , but to develop a long-term technology based on organic materials with almost unlimited availability. Before these cells become practical, which at the moment still looks far away, the efficiency will have to be increased further. The long-term Over the last decade, organic polymeric thin films for photonic applications have been a rapidly growing research area. Conjugated polymers 42,54 are the classes of plastic materials, in which semiconducting characteristics can be observed as given in Figure 12. Conjugated polymers become conducting in the doped state. These are polymers that possess a meta-and para-linkages 67b. Suzuki coupling between dibromotriarylamine and phenylene-1,4-diboronic ester also resulted in a sparingly soluble poly(triarylamine) with low molecular weight possessing highly efficient blue photoluminescence 68. All synthetic methods for preparation of polymeric triarylamines described above are illustrated in Scheme 1. Polythiophenes Polythiophenes are an important representative class of conjugated polymers that form some of the most environmentally and thermally stable materials that can be used as electrodes 73 , sensors 74 , transistors 75 , polymer LEDs 76 , solar cells etc. Polythiophene and its derivatives work very well in some of the above applications and less impressively in other devices. Creative new design and development strategies of new polythiophenes has led to interesting new materials and enhanced performance in certain devices. The ability of molecular designers to begin understanding how to gain control over the structure, properties, and function in polythiophenes continue in order to make the synthesis of polythiophenes a critical subject in the development of new advanced materials. Pure polythiophene without side chains is neither soluble nor fusible. Once the polymer is prepared, it's not possible to further process the obtained film or powder. However, side chains, which give solubility and fusibility to the polymer, can be attached to the thiophene ring. The most widely used polymer is the poly(3-hexylthiophene) (P3HT). Since 3-alkylthiophene is not a symmetrical molecule, the band gap and conductivity of poly(3-alkylthiophene)s are strongly dependent on regioregularity of these polymers. There
Electrochimica Acta, 2003
Poly(3,4-dialkoxythiophene) films with different length of alkyl chain (1,3 and 8 carbon atoms) were obtained on Pt and ITO electrodes from the monomer solutions in acetonitrile by cyclic voltammetry (CV). The properties of the resulting films were studied by electrochemical methods, UV Á/Vis, FTIR and NMR spectra. The CVs were correlated with differential cyclic voltabsorptograms (DCVA) recorded at the absorption maxima to explain the shape of the voltammograms of the polymers studied, dependent on the alkyl-chain length in alkoxy group. The presence of the zones of different crystallinity in the polymer film was postulated. Significant influence of the type of the solvent on asymmetry of the cyclic voltammograms for the polymer doping Á/undoping has been discussed in terms of the solvent interaction with radical cation (polaron) delocalized on the alkoxy side groups. The polaron delocalization was proved by 1 H-NMR spectra. Appearance of infrared activated vibrations (IRAVs) in the range 1500 Á/600 cm (1 and a characteristic electronic band at 3300 cm (1 at the polarization potential '/0.25 V versus Ag/Ag ' and their gradual changes upon further polymer oxidation were interpreted in terms of evolution of different charge carriers in lightly and heavily doped polymer.
Electrochemical and optical properties of novel donor-acceptor thiophene-perylene-thiophene polymers
Journal of Polymer Science Part A: Polymer Chemistry, 2008
In this study, donor-acceptor type thiophene-perylene-thiophene monomers were synthesized and polymerized by both oxidative polymerization using FeCl 3 as catalyst and the electrochemical process. UV-vis, FTIR, 1 H NMR, and elemental analysis techniques were used for structural characterization. Thermal behaviors of these compounds were determined by using TGA system. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels and electrochemical and optical band gap values were calculated by using the results of cyclic voltammetry and UV-vis measurements, respectively. The numberaverage molecular weight (M n ), weight-average molecular weight (M w ), and polydispersity index (PDI) values of synthesized polymers were determined by size exclusion chromatography. Conductivity measurements of these polymers were carried out by electrometer by using a four-point probe technique. The conductivity was observed to be increased by iodine doping. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym