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1.
Shear moduli were determined for chemically polymerized and solvent cast regioregular poly(3-hexylthiophene) films, using thickness shear mode acoustic wave resonators. The results are strikingly different to those for electropolymerized regiorandom poly(3-hexylthiophene) films. The time scale of the measurement was varied directly by use of higher harmonics of the acoustic wave resonator and indirectly via temperature. The significant variations in shear modulus with effective time scale can be "normalized"onto a stress master relaxation curve by using the concept of time-temperature superposition; this is the first time this has been demonstrated for electroactive films. The shift factors required to effect this normalization do not follow the classical Williams-Landel-Ferry (WLF) equation developed for long-range backbone motions of bulk polymers. Instead, they follow an Arrhenius-like behavior, commonly used to describe secondary motions of polymer side-chains. The activation enthalpy associated with this is independent of applied potential, is the same as for as cast (undoped) films, and is similar to that for rotation about a carbon-carbon single bond. These all point to the hexyl side-chains as the origins of the observed phenomena, consistent with the "melting point" separating two temperature-dependent phases and with the different molecular packing arrangements that would necessarily apply to regioregular and regiorandom materials. 相似文献
2.
Kyle N. Baustert Ashkan Abtahi Ahmed N. Ayyash Kenneth R. Graham 《Journal of polymer science. Part A, Polymer chemistry》2022,60(3):602-609
Chemical and electrochemical doping of π-conjugated polymers is an important aspect in determining the performance and enabling the operation of many organic electronic devices, from organic light emitting diodes and thermoelectrics to organic electrochemical transistors. In both chemical doping and electrochemical doping an ionized dopant or counterion is present along with the doped π-conjugated polymer. This dopant or counterion is not a benign spectator, rather, its presence can significantly impact the optical, electronic, and thermoelectric properties of the resulting material. Here, we investigate how counterion structure impacts the electrochemical doping ability, oxidation potential, ionization energy, and polaron absorbance of regioregular (rr) and regiorandom (rra) P3HT. We find that in most cases the anion has a small effect on the polymer oxidation potential, except for in the case of rr-P3HT with the large tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion. We propose that this large anion is excluded from the crystalline regions and thus the oxidation potential is similar to that of rra-P3HT. The anions also result in significant differences in polaron absorbance and ionization energies, thereby emphasizing the important role of the counterion in determining the optical and electronic properties of doped π-conjugated polymers. 相似文献
3.
Radano CP Scherman OA Stingelin-Stutzmann N Müller C Breiby DW Smith P Janssen RA Meijer EW 《Journal of the American Chemical Society》2005,127(36):12502-12503
Block copolymers of regioregular poly(3-hexylthiophene) (P3HT) and polyethylene (PE) were synthesized through the chain transfer of olefin-terminated P3HT in the presence of cyclooctene via ring-opening metathesis polymerization (ROMP). Subsequent hydrogenation of the poly(cyclooctene) block yielded high molecular weight, crystalline-crystalline P3HT-PE block copolymers, which are thermally stable and resistant to solvents under ambient conditions. These copolymers were characterized by 1H NMR, DSC, and WAXS and represent the first materials of a class of crystalline-crystalline semiconducting-insulating block copolymers. 相似文献
4.
Matsui J Yoshida S Mikayama T Aoki A Miyashita T 《Langmuir : the ACS journal of surfaces and colloids》2005,21(12):5343-5348
Semiconducting thin films consisting of regioregular poly(3-hexylthiophene) (RR-PHT) and poly(N-dodecylacrylamide) (pDDA) were constructed by the Langmuir-Blodgett (LB) technique. A mixture of RR-PHT and pDDA spread from a chloroform solution on a water surface forms a stable monolayer, which can be transferred onto solid substrates by the LB method, yielding a well-defined polymer LB film. Surface morphology studies of the LB film indicate that the RR-PHT is dispersed uniformly throughout the surface. The polymer thin film was chemically doped by contacting with FeCl3 acetonitrile solution, and a conductivity of 5.6 S/cm was achieved. Further, the LB film was utilized as the semiconducting film in the field-effect transistor (FET), and mobilities of 2.2 x 10(-4) and 4.4 x 10(-4) cm2 V(-1) s(-1) were obtained by analyzing the saturated and linear regions of the current-voltage characteristic, respectively. 相似文献
5.
Zhang R Li B Iovu MC Jeffries-El M Sauvé G Cooper J Jia S Tristram-Nagle S Smilgies DM Lambeth DN McCullough RD Kowalewski T 《Journal of the American Chemical Society》2006,128(11):3480-3481
Low polydispersity regioregular polythiophenes with number average molecular weights ranging from 2 to 13 kDa were cast under the same conditions from solution to form a series of field effect transistors (FETs). Tapping mode AFM and grazing incidence small-angle X-ray scattering revealed that in all cases the polymers formed regular nanofibrillar morphologies with the width of nanofibrils proportional to the weight average contour length of polymer chains, indicating that conjugated backbones were oriented perpendicular to the nanofibril axes. FET charge carrier mobilities exhibited exponential dependence on nanofibril width, pointing to the decisive role of extended conjugated pathways in charge transport. 相似文献
6.
Spano FC 《The Journal of chemical physics》2005,122(23):234701
Absorption and emission in polymer aggregates is studied theoretically, taking into account excitonic (intermolecular) coupling, exciton-phonon (EP) coupling, and disorder, all treated on equal footing within a generalized Holstein Hamiltonian with numerically generated eigenmodes and energies. The disorder is modeled as a Gaussian distribution of molecular transition frequency offsets of width sigma and spatial correlation length l(0). Both herringbone (HB) and lamellar aggregate morphologies are considered. The emission spectral line shape is shown to undergo marked changes in response to increasing disorder, with the intensity of the ac-polarized 0-0 emission peak generally increasing relative to the replica intensities (0-1,0-2,[ellipsis (horizontal)]) as sigma increases and/or as l(0) decreases. This is contrary to the behavior of the b-polarized component of the 0-0 intensity, which, in HB aggregates, decreases with increasing disorder. Comparisons are made to analogous trends in oligomer aggregates. Analytical results are obtained in the strong EP coupling regime appropriate for conjugated polymers while treating the disorder perturbatively. A method for uniquely determining sigma and l(0) from the emission and absorption spectra is presented. Applications are made to absorption and low-temperature emission in thin films of regioregular poly(3-hexylthiophene), with excellent agreement between theory and experiment obtained for a spatial correlation length of only 3-4 molecules. 相似文献
7.
Acevedo-Peña Próspero Baray-Calderón Alejandro Hu Hailin González Ignacio Ugalde-Saldivar Víctor M. 《Journal of Solid State Electrochemistry》2017,21(8):2407-2414
Journal of Solid State Electrochemistry - Though poly(3-hexylthiophene) (P3HT) is one of the most commonly used polymers in organic solar cells, a broad range of values, derived from cyclic... 相似文献
8.
Bontempo D Li RC Ly T Brubaker CE Maynard HD 《Chemical communications (Cambridge, England)》2005,(37):4702-4704
Low polydispersity poly(N-isopropylacrylamide) with a biotin end-group was obtained in one step from a biotinylated initiator for atom transfer radical polymerization and interacted with streptavidin to generate the thermosensitive polymer-protein conjugate. 相似文献
9.
Stefopoulos AA Chochos CL Bokias G Kallitsis JK 《Langmuir : the ACS journal of surfaces and colloids》2008,24(19):11103-11110
The synthesis of a random copolymer through free radical copolymerization of a properly vinyl monofunctionalized regioregular poly(3-octylthiophene) (rrP3OT) macromonomer and N,N'-dimethylacrylamide (DMAM) is presented. The optical properties of the copolymer in water and in several organic solvents of varying polarity, as well as in THF/water and THF/methanol mixtures, were explored using UV-vis and photoluminescence spectroscopy. It is demonstrated that the rrP3OT chains adopt a coil conformation in solvents such as tetrahydrofuran (THF) and chloroform with the appearance of the absorption and emission maxima at 439 and 565 nm, respectively. On the contrary, the rrP3OT chains are organized on a single chain packing form (intrachain interactions) in polar solvents such as ethanol and methanol, as it is verified with the observation of the characteristic three vibronic features of the absorption spectra of the copolymer with maxima at 513, 550, and 603 nm and emission maxima at 560 nm. However, when water is used as solvent, the rrP3OT chains self-assemble into a stacklike structure due to the increased interchain interactions, as confirmed by the different aggregation process of the rrP3OT chains in the THF/water mixture, the broader absorption spectrum in water compared to those recorded in ethanol and methanol, and the 80 nm red-shifted emission maximum, centered at 640 nm. 相似文献
10.
Wang X Ederth T Inganäs O 《Langmuir : the ACS journal of surfaces and colloids》2006,22(22):9287-9294
Changes in the contact angle between conjugated polymers surface poly(3-hexylthiophene) [P3HT] and poly(3,4-ethylenedioxythiophene) (PEDOT) upon electrochemical doping-dedoping in aqueous electrolyte were determined in situ using a Wilhelmy plate tensiometer in an electrochemical cell. The hydrophobic P3HT was less hydrophobic in the oxidized state than in the neutral state; the more hydrophilic PEDOT was less hydrophilic in the oxidized state than when neutral. The tensiometry results were in good agreement with those measured by contact angle goniometry, and further corroborated by the capillary rise upon doping in a fluid cell with two parallel polymer coated plates, another in situ dynamic determination method. The contact angle changes depend on doping potential, electrolyte type, and concentration. We also deconvoluted the surface energy into components of van der Waals and acid-base interactions, using three probe liquids on the polymer surfaces, ex situ the electrochemical cell. The methods and the obtained results are relevant for the science and technology areas of printed electronics and electrochemical devices and for the understanding of surface energy modification by electrochemical doping. 相似文献
11.
The measurement of crystallinity and orientation in poly(ethylene terephthalate) is discussed. A simple procedure is given for the estimation of orientation from the (1 05) plane, and it is shown that methods which use the equatorial planes are subject to certain disadvantages. In addition a method is given for the measurement of x-ray crystallinity. The technique is applied to fibers and films of various treatments and a linear relation is found between density and x-ray crystallinity. 相似文献
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15.
Aurélie Dupuis Pascal Wong-Wah-Chung Agnès Rivaton Jean-Luc Gardette 《Polymer Degradation and Stability》2012,97(3):366-374
The influence of the microstructure of poly(3-hexylthiophene) (P3HT) on its photodegradation upon exposure to UV-visible light was studied. High-regioregular (>98%) and low-regioregular (<95%) P3HTs with different molecular weights, dispersities and purities were submitted to irradiation under accelerated artificial ageing conditions. While the molecular weight had no effect on the photodegradation rate, a linear relationship was observed between the photodegradation rate and the regioregularity. The higher photo-instability of low-regioregular P3HTs, which have low crystalline phase content, could be due to the fact that the radical chain oxidation occurs predominantly in the amorphous phase of the polymer. Low-regioregular P3HTs also have a higher number of impurities, especially Fe residues, which are well known for their photocatalytic effect. The results also show that, at low concentrations, oxidation products are able to quench the singlet state of P3HT by acting as electron traps, and that the shortest wavelengths of solar light are the most harmful. Finally, the photooxidation of P3HT leads to the formation of low-molecular-weight carboxylic acids that can easily diffuse and migrate out of low-regioregular P3HT thin films. These results are therefore relevant to the preparation, storage and lifetimes of P3HT-based organic solar cells. 相似文献
16.
With the objective of developing new biodegradable materials, the miscibility and the crystallinity of blends of poly(3-hydroxybutyrate), P(3HB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV), have been studied. P(3HB) (300 kg mol−1)/P(3HB-co-3HV)–10% 3HV (340 kg mol−1) blends were prepared by casting in a wide range of proportions, and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The experimental values for the glass transition temperatures (Tg) are in good agreement with the values provided by the Fox equation, showing that the blends are miscible. It was observed that the Tg and the melting temperature (Tm) decreases with the increase in the P(3HB-co-3HV)–10% 3HV content, while the crystallization temperature (Tc) increases. FT-IR analyses confirmed the decrease on the crystallinity of P(3HB)/P(3HB-co-3HV)–10% 3HV blends with higher copolymer contents. Bands related to the crystallinity were changed, due to the copolymer content that produced miscible and less crystalline blends. 相似文献
17.
Two regioregular poly(p-phenyleneethynylene-alter-m-phenyleneethynylene)s bearing (−)-trans-myrtanoxyl side groups with different substitution patterns were designed and synthesized, e.g. Myr-PMPE-1 and Myr-PMPE-2.
In Myr-PMPE-1, the side chiral groups are distributed uniformly along the backbone. In Myr-PMPE-2, the distribution of the
side chiral groups is alternatively crowded and loose. Both of these two polymers show no CD signal in solutions because of
their good solubility. The investigations of chiroptical properties of these two polymers were carried out in the form of
spin-coated films. The films were annealed above the glass temperature of the corresponding polymer, and the effects of annealing
temperature and time on the properties of the films were investigated by UV-Vis absorption, fluorescence and circular dichroism
spectra. The results show that annealing treatment had no significant effect on the properties of Myr-PMPE-1, including UV-Vis
absorption, fluorescence and optical activity. The maximum absolute value of dissymmetry factor (|g
max|) was 1.62 × 10−4. On the other hand, annealing treatment significantly affected the properties of Myr-PMPE-2. Without annealing or being annealed
below 100°C, Myr-PMPE-2 films show almost no Cotton effect. In contrast, when annealed above 120°C, the absorption and emission
of Myr-PMPE-2 films slightly red shifted with increasing annealing temperature and annealing time. Most importantly, the intensity
of CD signals increased significantly and the optical activity of Myr-PMPE-2 films markedly increased. After annealing at
140°C for 4 h, the |g
max| of Myr-PMPE-2 films was increased up to 3.07 × 10−3, about one order of magnitude higher than that of Myr-PMPE-1 films.
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Translated from Acta Polymeric Sinica, 2008, 3 (in Chinese) 相似文献
18.
Matthieu Manceau Agnès Rivaton Stéphane Guillerez 《Polymer Degradation and Stability》2009,94(6):898-907
Poly(3-hexylthiophene) (P3HT) has been the focus of great interest as it is widely used in organic solar cells. However, P3HT has relatively poor photochemical and thermal stability under ambient atmosphere, which leads to a reduced lifetime of the solar cells. It was therefore necessary to study the photo- and thermooxidation of P3HT. Thin P3HT films were exposed to UV-visible light irradiation and thermal ageing, both in the presence of air. Changes in the infrared spectra of the aged samples were recorded, and the oxidation products were identified. A degradation mechanism that accounted for the modifications in the infrared spectra was then developed. This mechanism confirmed that singlet oxygen plays no decisive role, as previously reported. Oxidation was shown to involve the radical oxidation of the n-hexyl side-chains and the subsequent degradation of the thiophene rings. The breaking of the macromolecular backbone resulted in a loss of π-conjugation, provoking the bleaching of the sample. 相似文献
19.
Magnetic, relaxation, and dynamic parameters of radical pairs of positively charged polarons and negatively charged anion
radicals of fullerene that are induced by photons with an energy of 1.7–3.4 eV are studied by the methods of photoinduced
electron paramagnetic resonance for the poly(3-hexylthiophene)fullerene composite. The above charge carriers show mutual independence,
which is provided by a different interaction with their microenvironment. The paramagnetic susceptibility of spin pairs reflects
the dipoledipole interaction and activation dynamics of paramagnetic sites in the polymer-fullerene system. The rate of recombination
of radical pairs is controlled by the mutual space distribution of carriers of various charges and by the energy of excitation
photons. Quasi-one-dimensional diffusion of polarons along polymer chains and rotational diffusion of fullerene molecules
about the selected molecular axis are likewise controlled by the energy of photons and can be described in terms of the activation
Elliott hopping model. The dependence of the main values of magnetic, relaxation, and dynamic parameters of charge carriers
on the energy of photons is explained by the inhomogeneous distribution of molecular clusters in the polymer-fullerene composite.
The annealing of this composite leads to an enhanced formation of polymer crystallites and fullerene clusters. Hence, the
effective dimension of the system increases and its electron characteristics are improved. 相似文献
20.
Anton Li David Bilby Ban Xuan Dong Jojo Amonoo Jinsang Kim Peter F. Green 《Journal of polymer science. Part A, Polymer chemistry》2016,54(2):180-188
An epitaxy-directing solvent additive 1,3,5-trichlorobenzene is combined with an off-center spin-casting technique to produce poly(3-hexylthiophene) (P3HT) fibers with uniaxial in-plane alignment on the centimeter scale. Photoconductive atomic force microscopy (pc-AFM) is used to characterize planar heterojunction devices assembled from phenyl-C61 butyric acid methyl ester (PCBM) acceptor and both aligned and unaligned P3HT donor. By varying the relative positions of the laser spot (site of carrier generation) and probe (site of hole extraction), it is found that devices with aligned P3HT exhibit anisotropic and greatly enhanced long-range photocarrier transport, with nearly 10% of original photocurrent measured 400 µm from the laser spot along the direction parallel to the alignment. Complementary thin film transistor (TFT) measurements reveal a factor of ∼3.5 difference in the hole mobilities parallel and perpendicular to the direction of alignment. Together, these findings highlight the importance of macroscopic alignment as a strategy to overcome the low mobilities of disordered polymer semiconductors.1 © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 180–188 相似文献