Synthesis of Isothianaphthene (ITN) and 3,4-Ethylenedioxy-Thiophene (EDOT)-Based Low-Bandgap Liquid Crystalline Conjugated Polymers.
Ontology highlight
ABSTRACT:
SUBMITTER: Wang A
PROVIDER: S-EPMC5458956 | biostudies-other | 2013 May
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Directed alignment of polymer chains plays an indispensable role in charge transport properties. We focus not only on a specific method to induce the alignment but also on the design of a liquid crystalline (LC) conjugated polymer to take advantage of an intrinsic self-assembly characteristic. We synthesized a lyotropic LC conjugated polymer, CP1-P, having o-nitrobenzyl (ONB) esters as photocleavable side chains and adopted a floating film transfer method to induce the polymer chain alignment through a lyotropic LC phase transition. An optimum amount of a high boiling point solvent (1,2-dichlorobenzene) in chloroform turned out to be an important factor to maximize the polymer chain alignment. The hole transport mobility along the polymer chain alignment direction was 13-14 times higher than that in the direction perpendicular to the alignment. In addition, the removal of side chains resulted in the solvent resistivity while maintaining the alignment feature in organic thin-film transistors.
| S-EPMC6643927 | biostudies-literature
Project description:Two novel aromatic imides, diarylcyclopentadienone-fused naphthalimides (BCPONI-2Br and TCPONI-2Br), are designed and synthesized by condensation coupling cyclopentadienone derivatives at the lateral position of naphthalimide skeleton. It has been found that BCPONI-2Br and TCPONI-2Br are highly electron-withdrawing acceptor moieties, which possess broad absorption bands and very low-lying LUMO energy levels, as low as -4.02 eV. On the basis of both building blocks, six low bandgap D-A copolymers (P1-P6) are prepared via Suzuki or Stille coupling reactions. The optical and electrochemical properties of the polymers are fine-tuned by the variations of donors (carbazole, benzodithiophene, and dithienopyrrole) and π-conjugation linkers (thiophene and benzene). All polymers exhibit several attractive photophysical and electrochemical properties, i.e., broad near-infrared (NIR) absorption, deep-lying LUMO levels (between -3.88 and -3.76 eV), and a very small optical bandgap ( E g opt ) as low as 0.81 eV, which represents the first aromatic diimide-based polymer with an E g opt of <1.0 eV. An investigation of charge carrier transport properties shows that P5 exhibits a moderately high hole mobility of 0.02 cm2 V-1 s-1 in bottom-gate field-effect transistors (FETs) and a typical ambipolar transport behavior in top-gate FETs. The findings suggest that BCPONI-2Br, TCPONI-2Br, and the other similar acceptor units are promising building blocks for novel organic semiconductors with outstanding NIR activity, high electron affinity, and low bandgap, which can be extended to various next-generation optoelectronic devices.
| S-EPMC6549120 | biostudies-literature
Project description:In this study, we reported the synthesis of a new tribranched macromolecule liquid crystal with triazine in the centre. The central triazine core is bonded via sequences of Sonigashira coupling to 3 triazine unites through acetylenic bridges. The triazines at the periphery are substituted with 2 chiral citronellyloxy side groups. The salt of the resulting star-shaped macromolecule, which was oily at room temperature, with 4-dodecyloxybenzoic acid at 1:1 ratio exhibited a Smectic C (SmC) mesophase. The liquid crystalline properties of organic salt were investigated using DSC (differential scanning calorimetry) and POM (polarizing optical microscopy).
| S-EPMC7671215 | biostudies-literature
Project description:The syntheses of new thermotropic liquid crystalline polymers (TLCPs) were carried out via the polyaddition reactions of diepoxy-containing mesogens and a monoamine (1-naphthylamine). Both bulk polymerization and reactive extrusion were tested. The reaction between the two epoxy rings on the mesogen unit and the primary amine produces a thermotropic liquid crystalline polymer in the extruder. The amine group combines with the two epoxy rings in a single step via a polyaddition reaction to produce thermotropic liquid crystalline polymers without the formation of any by-products. Both polymers were found to exhibit nematic mesophase characteristics, which were examined by using polarized optical microscopy. The new thermotropic liquid crystalline polymers obtained with the bulk reaction have high molecular weights, whereas the polymers synthesized by using reactive extrusion have low molar mass due to their short residence times in the extruder. All the synthesized TLCPs were found to exhibit high thermal stability. Their decomposition temperatures were found to be above 350 °C, but their melting temperatures are low (below 250 °C). The liquid crystalline structures of the TLCPs were verified by performing 2D X-ray diffraction measurements. Scanning electron micrographs of the drawn polymer fibers show that the orientation of their morphologies lies predominantly along the direction of the fibers. The polymers synthesized with the reactive extrusion process have the same physical properties as those obtained with the bulk polyaddition reaction. This observation demonstrates the feasibility of the mass production of new TLCPs through reactive extrusion.
| S-EPMC9063539 | biostudies-literature
Project description:Low-bandgap diketopyrrolopyrrole- and carbazole-based polymer bulk-heterojunction solar cells exhibit much faster charge carrier recombination kinetics than that encountered for less-recombining poly(3-hexylthiophene). Solar cells comprising these polymers exhibit energy losses caused by carrier recombination of approximately 100 mV, expressed as reduction in open-circuit voltage, and consequently photovoltaic conversion efficiency lowers in more than 20%. The analysis presented here unravels the origin of that energy loss by connecting the limiting mechanism governing recombination dynamics to the electronic coupling occurring at the donor polymer and acceptor fullerene interfaces. Previous approaches correlate carrier transport properties and recombination kinetics by means of Langevin-like mechanisms. However, neither carrier mobility nor polymer ionization energy helps understanding the variation of the recombination coefficient among the studied polymers. In the framework of the charge transfer Marcus theory, it is proposed that recombination time scale is linked with charge transfer molecular mechanisms at the polymer/fullerene interfaces. As expected for efficient organic solar cells, small electronic coupling existing between donor polymers and acceptor fullerene (Vif < 1 meV) and large reorganization energy (? ? 0.7 eV) are encountered. Differences in the electronic coupling among polymer/fullerene blends suffice to explain the slowest recombination exhibited by poly(3-hexylthiophene)-based solar cells. Our approach reveals how to directly connect photovoltaic parameters as open-circuit voltage to molecular properties of blended materials.
| S-EPMC3646405 | biostudies-literature
Project description:To address the limitations of conventional Pd catalysts in the polymerization of thiophene-containing conjugated polymers, an active catalyst system based on Pd (0) and a phosphine-based bulky ligand, L1, is explored systematically in Suzuki-Miyaura polymerizations using thiophene boronic acid pinacol ester as one of the monomers. This active catalyst is found very efficient in synthesizing a series of thiophene-containing linear and hyperbranched conjugated polymers. First, as a model example, coupling reactions between electron-rich/moderately hindered aryl or thienyl halides and thiophene boronic acid pinacol ester give excellent yields with lower catalyst loading and can be completed in a shorter reaction time relative to Pd(PPh3)4. Notably, high molecular weight thiophene-containing polymers are successfully synthesized by Suzuki-Miyaura polycondensation of 2,5-thiophene bis(boronic acid) derivatives with different dibromo- and triple bromo-substituted aromatics in 5-15 min.
| S-EPMC8452923 | biostudies-literature
Project description:A total of six conjugated polymers, namely PDBT-Th, PDBT-Th:Th, PDBT-2Th, PDBT-Th:2Th, PDBT-2Th:Th, and PDBT-2Th:2Th, consisting of dibenzothiophene, thiophene, and bithiophene were electrochemically synthesized. Their electrochemical and electrochromic properties were investigated in relation to the conjugation chain lengths of the thiophene units in the conjugated backbones. Density functional theory (DFT) calculations showed that longer conjugation lengths resulted in decreased HOMO-LUMO gaps in the polymers. The optical band gaps (E g,opt) and electrochemical band gaps (E g,cv) were decreased from PDBT-Th to PDBT-Th:Th, however, PDBT-Th:2Th, PDBT-2Th, PDBT-2Th:Th and PDBT-2Th:2Th displayed the similar band gaps. The conjugation length increments significantly improved the electrochemical stability of the conjugated polymers and exhibited reversible color changes due to the formation of polarons and bipolarons. The results suggest that the conjugated polymers prepared herein are promising candidates for fabricating flexible organic electrochromic devices.
| S-EPMC7505771 | biostudies-literature
Project description:A new series of thiophene-based azomethines differing in the core structure was synthesized. The effect of the central core structure in azomethines on the thermal, optical and electrochemical properties was investigated. The obtained compounds exhibited the ability to form a stable amorphous phase with a high glass transition temperature above 100 °C. They were electrochemically active and undergo oxidation and reduction processes. The highest occupied (HOMO) and the lowest unoccupied molecular (LUMO) orbitals were in the range of -3.86--3.60 eV and -5.46--5.17 eV, respectively, resulting in a very low energy band gap below 1.7 eV. Optical investigations were performed in the solvents with various polarity and in the solid state as a thin film deposited on a glass substrate. The synthesized imines absorbed radiation from 350 to 600 nm, depending on its structure and showed weak emission with a photoluminescence quantum yield below 2.5%. The photophysical investigations were supported by theoretical calculations using the density functional theory. The synthesized imines doped with lithium bis-(trifluoromethanesulfonyl)imide were examined as hole transporting materials (HTM) in hybrid inorganic-organic perovskite solar cells. It was found that both a volume of lithium salt and core imine structure significantly impact device performance. The best power conversion efficiency (PCE), being about 35-63% higher compared to other devices, exhibited cells based on the imine containing a core tiphenylamine unit.
| S-EPMC9330727 | biostudies-literature
Project description:This paper describes effects of the flexibility, length, and branching of side chains on the mechanical properties of low-bandgap semiconducting polymers. The backbones of the polymer chains comprise a diketopyrrolopyrrole (DPP) motif flanked by two furan rings and copolymerized by Stille polycondensation with thiophene (DPP2FT). The side chains of the DPP fall into three categories: linear alkyl (C8, C14, or C16), branched alkyl (ethylhexyl, EH, or hexyldecyl, HD), and linear oligo(ethylene oxide) (EO3, EO4, or EO5). Polymers bearing C8 and C14 side chains are obtained in low yields and thus not pursued. Thermal, mechanical, and electronic properties are plotted against the number of carbon and oxygen atoms in the side chain. We obtain consistent trends in the thermal and mechanical properties for branched alkyl and linear oligo(ethylene oxide) side chains. For example, the glass transition temperature (T g) and elastic modulus decrease with increasing number of carbon and oxygen atoms, whereas the crack-onset strain increases. Among polymers with side chains of 16 carbon and oxygen atoms (C16, HD, and EO5), C16 exhibits the highest T g and the greatest susceptibility to fracture. Hole mobility, as measured in thin-film transistors, appears to be a poor predictor of electronic performance for polymers blended with [60]PCBM in bulk heterojunction (BHJ) solar cells. For example, while EO3 and EO4 exhibit the lowest mobilities (< 10-2 cm2 V-1 s-1) in thin-film transistors, solar cells made using these materials performed the best (efficiency > 2.6%) in unoptimized devices. Conversely, C16 exhibits the highest mobility (≈ 0.2 cm2 V-1 s-1) but produces poor solar cells (efficiency < 0.01%). We attribute the lack of correlation between mobility and power conversion efficiency to unfavorable morphology in the BHJ solar cells. Given the desirable properties measured for EO3 and EO4, the use of flexible oligo(ethylene oxide) side chains is a successful strategy to impart mechanical deformability to organic solar cells, without sacrificing electronic performance.
| S-EPMC6411084 | biostudies-literature
Project description:Narrow bandgap conjugated polymers are a heavily studied class of organic semiconductors, but their excited states usually have a very short lifetime, limiting their scope for applications. One approach to overcome the short lifetime is to populate long-lived triplet states for which relaxation to the ground state is forbidden. However, the triplet lifetime of narrow bandgap polymer films is typically limited to a few microseconds. Here, we investigated the effect of film morphology on triplet dynamics in red-emitting conjugated polymers based on the classic benzodithiophene monomer unit with the solubilizing alkyl side chains C16 and C2C6 and then used Pd porphyrin sensitization as a further strategy to change the triplet dynamics. Using transient absorption spectroscopy, we demonstrated a 0.45 ms triplet lifetime for the more crystalline nonsensitized polymer C2C6, 2-3 orders of magnitude longer than typically reported, while the amorphous C16 had only a 5 μs lifetime. The increase is partly due to delaying bimolecular electron-hole recombination in the more crystalline C2C6, where a higher energy barrier for charge recombination is expected. A triplet lifetime of 0.4 ms was also achieved by covalently incorporating 5% of Pd porphyrin into the C16 polymer, which introduced extra energy transfer steps between the polymer and porphyrin that delayed triplet dynamics and increased the polymer triplet yield by 7.9 times. This work demonstrates two synthetic approaches to generate the longest-lived triplet excited states in narrow bandgap conjugated polymers, which is of necessity in a wide range of fields that range from organic electronics to sensors and bioapplications.
| S-EPMC9936540 | biostudies-literature