Browse Articles

Filter By:

  • Fused π−conjugated molecules have been utilized as key components in organic semiconductors due to their high charge-transport characteristics. In this study, we designed and synthesized a novel fused π−conjugated molecule composed of electron-donating benzodithiophene and electron-accepting naphthobisthiadiazole units and investigated its photo/electrochemical properties and semiconducting characteristics. The fused donor-acceptor-donor (DAD) molecule showed typical p-type characteristics with a hole mobility of 1.1 × 10−3 cm2 V−1 s−1. We also achieved the synthesis of a D-A type copolymer containing the fused DAD structure as an electron donor unit.

    • Ryo Asakawa
    • Takuji Seo
    • Yutaka Ie
    Original Article
  • As the performance of organic semiconductors has increased so has their molecular structure. In this focused review, we introduce the concept of synergistic catalysis, which involves the use of two or more catalysts with orthogonal reactivity to enable reactions that are not possible with the use of a single catalyst, to synthesize π-conjugated polymers. Synergistic catalysis allows for controlled polymerizations, room-temperature reactions, and/or polymerizations with greater regioselectivity, opening the door to more time-, labor-, cost-, and energy-saving synthetic methods.

    • C. K. Luscombe
    • S. Phan
    • I. Sanskriti
    Focus Review Open Access
  • Ternary phase diagrams of the solvent/donor/acceptor system were studied to discuss the relationship between the photovoltaic properties of polymer solar cells and the phase-separated structures. The downshifted intersection points between the solvent drying pathway and binodal lines suggest the smaller domain sizes, and hence the higher exciton diffusion efficiency. The appropriate acceptor volume fraction close to the percolation threshold in mixed-phase shows high charge collection efficiency due to an effective charge transport and a suppressed bimolecular recombination.

    • Jihun Jeon
    • Kiyotaka Doi
    • Hideo Ohkita
    Original Article
  • By integrating the strongly electron-deficient building blocks cyano-substituted benzochalcogenadiazole and diketopyrrolopyrrole, two A-A polymers were constructed and exhibited decent solubilities, low-lying LUMOs, and ultra-narrow bandgaps, thus leading to a predominant n-type transporting characteristics. When n-type doped with N-DMBI-H, the A-A polymers delivered an n-type performance with a power factor of 9.22 μW m−1 K−2. The design strategy is highly informative for further developing n-type organic thermoelectric materials.

    • Junwei Wang
    • Kui Feng
    • Xugang Guo
    Original Article
  • A better understanding of the carrier formation process for semiconducting polymers, especially in thin films, is essential for designing and constructing highly-functionalized polymeric optoelectronic devices. We herein examined effects of the crystalline structure and thermal molecular motion on photo-carrier formation for melt-crystalized thin films of monodisperse poly(3-hexylthiophene) (P3HT) with various molecular weights (MWs), which were prepared from polydisperse sample by preparative chromatography.

    • Daisuke Kawaguchi
    • Ayano Higasayama
    • Keiji Tanaka
    Original Article
  • C–H/C–I direct arylation reactions for monomer synthesis and C–H/C–Br direct arylation polycondensation were investigated for the short-step synthesis of promising medium-bandgap polymers (PBDB-T) for OPV applications. Polycondensation and end-capping reactions using direct arylation have been established, enabling the synthesis of polymers without Br termini. The OPV performance of the synthesized polymer was lower than that of the benchmark polymer synthesized using the conventional method, despite having similar molecular weights. Possible factors for low OPV performance and future challenges include structural defects, impurities, and large molecular weight distribution.

    • Junpei Kuwabara
    • Kota Hiyaji
    • Takaki Kanbara
    Original Article
  • The 2D WAXD/SAXS data collected using a synchrotron X-ray microbeam technique revealed the details of the lamellar twisting phenomenon of high-density polyethylene spherulites. The molecular mechanics calculation, performed for large aggregation models of alkane chains having bulky head groups or folded polyethylene chains, has successfully reproduced the lamellar twisting pitch of a few μm, as extracted from the X–ray data analysis.

    • Hiroko Yamamoto
    • Taiyo Yoshioka
    • Kohji Tashiro
    Original Article
  • Reversible complexation mediated polymerization (RCMP) was demonstrated in the presence of an aqueous phase using various amine catalysts and monomers to investigate the effect of hydrophobicity of amine catalysts and monomers on the polymerization control of RCMP in aqueous heterogeneous systems. The essential criteria for polymerization control were (i) sufficient hydrophobicity of initiators and catalysts to enable partitioning into monomer phases, (ii) a suitable I2 concentration and temperature for improving polymerization control using long-alkyl chain amine catalysts, and (iii) sufficient monomer hydrophobicity to suppress water solubilization into monomer phase.

    • Yukiya Kitayama
    • Daiki Tokura
    • Atsushi Harada
    Original Article
  • Azide-substituted polystyrene was reacted at both terminals of a poly(thieno[3,2-b]thiophen-2,5-diylbutadiynelene) derivative by a Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click postfunctionalization to form a coil-rod-coil type triblock copolymer. The resulting block copolymer exhibited higher solubilities than the precursor polymer, but the electronic properties of the conjugated polymer main chain were retained in the solid thin film state.

    • Kosuke Ogita
    • Naomasa Yomogita
    • Tsuyoshi Michinobu
    Original Article
  • Graphene-doped ZnO nanoplates (G-ZNPs) were incorporated as a reinforcing material into polyvinyl alcohol (PVA) to prepare nanocomposite PVA/G-ZNP hydrogels by forming a network structure of hydrogen and coordination bonding. G-ZNP improves the tensile property, swelling degree and dye adsorption capacity of PVA hydrogel, and also endows the hydrogel with excellent antibacterial properties.

    • Shuang Chen
    • Manuel Reyes De Guzman
    • Chih-Yuan Tsou
    Original Article
  • We describe here the new concept of developing stimuli-responsive luminochromic materials based on frustrated element-blocks. We termed “frustrated” element-blocks as those that show a relatively larger degree of structural relaxation in the excited state but are structurally restricted. Enhanced sensitivity toward environmental changes and external stimuli can be observed.

    • Kazuo Tanaka
    • Yoshiki Chujo
    Focus Review
  • Performance limiting factors in three end-group-brominated ITIC (β, γ, δ):PM6 bulk-heterojunction (BHJ) organic solar cells (OSCs) were investigated. The charge carrier dynamics (mobility and its relaxation) in these OSCs were evaluated by simultaneous time-of-flight (TOF)-time-resolved microwave conductivity (TRMC) measurement and photoinduced charge extraction by linearly increasing voltage (photo-CELIV) technique. The charge separation and recombination were found to be stronger power conversion efficiency-governing factors than mobilities and their balance, as suggested by regression analyses.

    • Shaoxian Li
    • Ryosuke Nishikubo
    • Akinori Saeki
    Original Article
  • We demonstrate the synthesis of head-to-tail (HT) regioregular poly(3-hexylthiophene) (P3HT) with controlled molecular weight via direct arylation polymerization (DArP). The key to control is using 2-phenylthiazole (2), which has a C–H bond with high reactivity for direct arylation, as the end-capping reagent. The DArP of 2-bromo-3-hexylthiophene (1) in the presence of 2 ([1]0/[2]0 = 10–80), Herrmann-Beller catalyst, and P(o-Me2NC6H4)3 afforded HT-regioregular P3HT (HT = 99%) capped with a 2-phenylthiazole-5-yl group. The number-average molecular weight (Mn) of P3HT agreed well with the value calculated by assuming the formation of one polymer chain per molecule of 2 (polydispersity index: Ð = 1.8–2.1).

    • Masayuki Wakioka
    • Kai Xu
    • Fumiyuki Ozawa
    Original Article
  • Vinylene-bridged 5-alkoxy-6-fluorobenzo[c][1,2,5]thiadiazole (FOBTzE) as a novel acceptor unit and its copolymer PFOE4T were designed and synthesized. The incorporation of an electron-donating alkoxy group instead of a fluorine atom prevented strong aggregation tendency and changed the molecular orientation of the polymers from edge-on to bimodal orientation, which was expected to provide uniform thin-film with PC61BM and promoted carrier transport. However, since PFOE4T has still strong aggregation ability and low solubility, the PFOE4T/PC61BM blended film formed a large phase separation, resulting in a power conversion efficiency of only 4.52%.

    • Hiroki Mori
    • Yuya Asanuma
    • Yasushi Nishihara
    Original Article
  • The folding behavior of a 2-dimethylaminoethyl methacrylate oligomer with alternately protonated side chains surrounded by water molecules was evaluated using molecular dynamics simulations in the temperature range of 280–360 K. Radial distribution functions (RDFs) around the geometric center of the oligomer were evaluated; they indicated that protonated amine groups surrounded the aggregating deprotonated amine groups in the globule state. The calculation of RDFs around the geometric center is a highly reliable strategy to evaluate the folding behavior of stimuli-responsive polymer gels during the coil-to-globule transition.

    • Ryo Nagumo
    • Kazuma Nishikawa
    • Shuichi Iwata
    Original Article
  • Optically active through-space conjugated polymers were prepared from planar chiral pseudo-meta-disubstituted [2.2]paracyclophane. The corresponding optically active pseudo-meta-linked dimers were also prepared, and their optical and chiroptical properties were compared with those of the pseudo-para- and pseudo-ortho-linked dimers. Optically active pseudo-meta-linked dimers and polymers emitted intense circularly polarized luminescence with good anisotropy factors on the order of 10–3. The electrical photoconductivities of the racemic pseudo-meta- and pseudo-para-linked polymers were also evaluated. A number of properties were explained by using time-dependent density functional theory calculations.

    • Hazuki Maeda
    • Ryo Inoue
    • Yasuhiro Morisaki
    Original Article
  • The effects of incorporating poly(d,l-lactide) (PDLLA) and solvent on the stereocomplex (SC) crystallization and homocrystallization of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) chains were explored using linear one-armed PLLA (1-L)/PDLA (1-D) and linear one-armed PDLLA (1-DL) as an unconstrained system and using four-armed PLLA-b-PDLA (4-L-D) and linear one-armed 1-DL as a constrained system. The dilution effects of PDLLA and solvent enhanced SC crystallization and suppressed homocrystallization, with the exception of the constrained 4-L-D/1-DL blends in the presence of both PDLLA and solvent.

    • Hideto Tsuji
    • Sena Nogata
    • Yuki Arakawa
    Original Article
  • In situ infrared spectroscopy and two-dimensional (2D) correlation analysis was applied to research the chemical changes and curing reaction mechanism of epoxy resin and amine curing agents. The curing reaction mechanism can be deeply understood from the results. Due to the nucleophilic addition reaction of amino and epoxy groups, the nitrogen atoms easily combine with the carbon atoms, which forms new C-N groups. Then, the C-O bonds break; finally, as the N-H bonds in primary amines break, the hydrogen atoms combine with the oxygen atoms to form new hydroxyl groups.

    • Zhipeng He
    • Wei Lv
    • Qinwei Yin
    Original Article
  • We investigated the hydration behaviors of PEG and PEGylated dendrimer using X-ray diffraction, infrared spectroscopy, and differential scanning calorimetry analysis in the range of −80 °C to 80 °C. At 20% water content, ice crystals were formed and melted during the heating. At 70% water content, however, PEG crystals were formed and melted. In the mixture of the PEGylated dendrimer with 20% water content, ice formation was suppressed. Comparative analyses are important for the evaluation of such eutectic mixtures of PEG compounds and water.

    • Chie Kojima
    • Yasuhito Suzuki
    • Akikazu Matsumoto
    Original Article
  • Conducting polymer support with atomically dispersed metal centers for oxygen reduction and evolution reaction catalysis is a promising strategy to enhance the cyclability of Li–O2 battery. We present a novel, reliable and highly efficient noble metal free polymer catalyst for Li air battery application. Novel cathode catalyst found to be very efficient for nearly 160 cycles with limiting the capacity to 500 mAh/g with relatively lower overpotential.

    • Rajashekar Badam
    • Mayu Shibuya
    • Noriyoshi Matsumi
    Original Article