Effect of π-conjugation on electrochemical properties of poly(terthiophene)s 3′-substituted with fullerene C60 (original) (raw)
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Electrochemical and photoelectronic studies on C60-pyrrolidine-functionalised poly(terthiophene)
Electrochimica Acta, 2014
A novel donor-acceptor poly(terthiophene) derivative bearing a C 60 pendant was electropolymerizated from N-methyl-2-(2-[4,4 '-didecyloxy-2,2 ;5 ,2 ']terthiophen-3 -yl-ethenyl)fullero[3,4]pyrrolidine (TTh-C 60 ) solution. The electroreduction of TTh-C 60 and poly(TTh-C 60 ) showed the presence of complex peaks related to fulleropyrrolidine reduction. The dual nature of these redox couples may be related to increasing Coulombic repulsion or coupling between C 60 substituents. Electrochemical, X-Ray photoelectron spectroscopy (XPS), Ultra-Violet photoelectron (UPS) and UV-Vis spectroscopy also confirm the nature of poly(TTh-C 60 ). Electrochemical band gap of poly(TTh-C 60 ) is 0.63 ± 0.20 eV in TBAP electrolyte and propylene carbonate (PC) solution. Furthermore, we obtained the value of optical energy band gap (E opt = 0.59 ± 0.03 eV), the transport energy band gap (E g trans = 1.17 ± 0.20 eV) and the exciton binding energy (E b = 0.58 ± 0.20 eV) for poly(TTh-C 60 ). The ionization energy values (IE) were determined using UPS spectroscopy (IE = 4.92 ± 0.10 eV) and electrochemical investigations of the poly(TTh-C 60 ) polarized in TBAP/DCM (IE = 5.01 ± 0.10 eV) and TBAP/PC solution (IE = 4.95 ± 0.10 eV) demonstrating good coincidence of the value. The electrochemical method revealed, that the location of the Fermi level relative to the valence and conduction bands indicates p-type character of semiconducting poly(TTh-C 60 ). On the other hand photoemission spectroscopy manifests n-type behavior of examined sample. In turn, the UV-Vis result showed that the charge transfer (CT) between poly(TTh) and C 60 unit can suggest, that these chromophores are not entirely independent.
Novel fullerene-functionalised poly(terthiophenes)
Journal of Electroanalytical Chemistry, 2007
A novel fullerene-functionalised terthiophene monomer, N-methyl-2-(2-[2,2 0 ;5 0 ,2 00-terthiophen-3 0-yl]ethenyl)fullero [3,4]pyrrolidine (TTh-BB), has been successfully electropolymerised to form the homopolymer, P(TTh-BB). The polymer has been characterised using cyclic voltammetry (CV), UV-Vis spectroscopy, scanning electron microscopy (SEM) and Raman spectroscopy. Preliminary studies into the use of this novel polymer as a cathode material in a lithium battery have been carried out here.
Electrochimica Acta, 2014
In this work we report electrochemical copolymerization of thiophene (Th) with thiophene-substituted fulleropyrrolidine (C 60 -ThFP) on Pt electrode from dichloromethane solution. A structure of the resultant donor-acceptor copolymer with high fullerene content, corresponding to one C 60 -ThFP per two thiophene units was determined by XPS and FTIR spectroscopy. The ratio of the two monomers in the polymer film was independently determined by electrochemical quartz crystal microbalance. Electroactivity of C 60 -ThFP and copolymer film in p-and n-doping ranges was studied by cyclic voltammetry. Geometry of a representative fragment of the synthesized copolymer was simulated by means of DFT calculations.
Photoelectrochemical properties of poly(terthiophene) films modified with a fullerene derivative
Thin Solid Films, 2006
This work reports on the photoelectrochemical properties of an interface comprised by poly(terthiophene) films electrochemically synthesized onto indium-tin oxide substrates and modified with 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C 61. Important photoelectrical parameters, such as flat band potential, density of charge carriers and depletion layer width were determined for the pristine and hybrid films. The cathodic photocurrent reflected the p-type semiconducting behavior of the electrosynthesized poly(terthiophene)s. Addition of the acceptor molecule improves the photocurrent at zero bias (∼ 6 μA cm − 2 at 100 mW cm − 2) indicating the fullerene derivative acts as an exciton dissociation center, improving the number of charge carriers transported through the polymer to reach the solid-liquid electrolyte interface.
Polythiophene regular copolymers bearing amino or nitro moieties directly linked to the conjugated backbone are produced by anodic coupling of 3 ,4-diamino-or 3 ,4-dinitro-terthiophenes. The polymers are characterized by cyclic voltammetry, FTIR reflection–absorption and UV–vis spectroscopy and in situ conductivity. Post-polymerization functionalization of polymer films leads to the quantitative transformation of the diamine to pyrazine and of the dinitro to diamine and subsequently pyrazine moieties. Conjugation of starting and ending functionalizations with the polythiophene backbone produces dramatic changes in electronic (electrochemical and optical) properties.
Journal of Materials Chemistry, 2002
A new series of regioregular poly(terthiophenes), bearing bis(thioether) side groups, has been prepared by electrochemical oxidation. Cyclic voltammetry of the parent trimers reveals an increase in electron donating ability in cyclic thioether derivatives. For example, one compound containing a central ethylenedithiothiophene (EDTT) unit gives two irreversible oxidation peaks which are significantly lower than the corresponding values for the structurally analogous bis(methylthio) derivative (DE 1ox~1 70 mV, DE 2ox~3 0 mV). The difference in oxidation potentials of each terthiophene in acetonitrile solution can be explained by examining the highest occupied molecular orbital (HOMO) energies. The electrochemical behaviour of the polymers illustrates the increase in p-doping ability of the EDTT-containing polymer. The cyclic voltammograms and electronic absorption spectra of the polymers show that the polymers containing cyclic thioether units have the lowest bandgap in the series (ca. 1.4 V and 1.5 eV, respectively). Photoinduced IR spectroscopy of poly(dithienyl-3,4ethylenedithiothiophene) provides evidence of a long-living photoexcited charged state in the polymer.
The electrochemical polymerisation of 3-hydroxymethyl-2,2 :5 ,2-terthiophene, afforded a new conducting polymer bearing the nucleophilic –CH 2 OH substituent in-position. The characteristics of the system obtained have been defined through electrochemical and spectroelectrochemical techniques, as a function of the nature of the solvent in which polymerisation has been carried out and in which polymer doping is electrochemically induced. Two different morphological and/or structural fractions are obtained when the polymer is electrogenerated in CH 3 CN solvent, while a more homogeneous deposit, consisting of molecules with shorter conjugation system, forms in CH 2 Cl 2. Marked differences are also evidenced when the polymer is p-doped in the two different solvents.
Electrochemically Polymerized Terthiophene Derivatives Carrying Aromatic Substituents
Macromolecules, 1994
A series of terthiophene derivatives substitituted with an aryl group R at the 3'-position of the central thiophene [R = H (l), phenyl (2), 4-cyanophenyl (3), 4-methoxyphenyl(4), 4-pyridyl(5), 2-thienyl (6), or 3-methyl-2-thienyl (7)] have been polymerized. Although the Substituents force the monomers to a nonplanar conformation, thus preventing the extension of conjugation to the side group, they influence the polymerizability and the properties of the resulting polymers. Solubilities of the oxidation products and inductive effects of the substituents are discussed in order to explain the differences. As-grown films of poly-1,-2,-3,-4, and-6 were soluble in chlorinated organic solvents. Poly-1 consists of monomers and dimers, but the polymerization degree of other soluble polymers was larger, as determined by matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS). The polymers are mixtures of oligomers in all cases, and the highest observed oligomers were heptamers (with poly-2 and-3). With the exception of poly-1,-4, and-5, the films could be both anodically and cathodically doped. A splitting of the cathodic undoping peak in cyclic voltammograms was observed with poly-6 and-7 and polythiophene. This behavior is analogous to the anodic undoping, suggesting a mechanistic symmetry in the doping processes. Spectral changes during undoping are interpreted by reactions of ionic species having different effective conjugation lengths. compartment cell from solutions of the corresponding monomer (0.05 M) and tetrabutylammonium hexafluorophosphate (0.2 M)
Synthesis of New Thienylene Pyrrole Monomers and Their Electropolymerizations
Journal of The Electrochemical Society, 2014
In this study, four new 2,5-dithienylpyrroles (SNS) 1-(3-fluoro-phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole (m-FPTP), 1-(3-chlorophenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole (m-ClPTP),1-(3-bromo-phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole (m-BrPTP) and 1-(4bromo-phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole (p-BrPTP) containing meta and para substituted benzene ring at the nitrogen atom were synthesized via Paal-Knorr condensation of 1,4-di(2-thienyl)-1,4-butanedione with corresponding halo-substituted anilines. The monomers were polymerized via potential cycling in LiClO 4-acetonitrile (ACN) electrolytic solution. The replacement effect of halogen atoms as a substituent from para-to meta-positions and different halogen units (F, Cl, Br) at only meta-/para-positions in the structure on the electrochemical and optical properties of synthesized monomers/polymers were investigated. Computational investigations (M06/TZVP) were also performed on the monomer structures to support the electrochemical behavior of the monomers and to get more insight about the conformation of the structures. Furthermore, the synthesized polymer films exhibited reversible redox behavior accompanied with a reversible electrochromic behavior. It was also observed that the optical contrast value (T%) for polymers was significantly improved when compared with their analogs in the literature.