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A polyurethane foam (PUF) loaded with poly(3‐hexylthiophene) (P3HT) nanofibers is fabricated as a thermoelectric (TE) material with low‐thermal conductivity. To date, there have been no reports on PUFs loaded with organic fillers, including conducting polymers, exhibiting TE properties. The P3HT nanofibers do not affect the polyurethane foaming reaction and are uniformly dispersed in the PUF. Generally, conductive fillers, including carbon fillers, result in brittle PUFs. However, the PUFs loaded with P3HT nanofibers exhibit mechanical strength and Young's modulus comparable to the PUFs without fillers, and the thickness can be completely restored even after compressing 20 times. Finally, it is confirmed that the PUF loaded with P3HT nanofibers exhibits TE properties, and the Seebeck coefficient is approximately 3 mV K−1, which is comparable to that of the conventional P3HT film reported previously. The soft PUF loaded with P3HT nanofibers can be regarded as a TE material with flexibility, mechanical toughness, and low‐thermal conductivity. [ABSTRACT FROM AUTHOR]

We study the initial nucleation dynamics of poly (3-hexylthiophene) (P3HT) in solution, with particular regard to the effect of rigid backbone length on the ordering dynamics. We carried out Langevin dynamics simulation, and found that the initial nucleation processes of P3HT in solution begin with the ring ordering, followed by the main chain ordering. In the meantime, ordering of side chains was slow and induced by the packing of main chains. This basic ordering mechanism is common regardless of chain length of P3HT in this study, although the longer chain systems showed slower growth than the shorter chain systems. Our simulation results demonstrated the unique and universal ordering features of comb-like polymers with flexible side chains and rigid main chains in the initial crystallization processes. [ABSTRACT FROM AUTHOR]

We study the initial nucleation dynamicsof poly(3-hexylthiophene)(P3HT) in solution, focusing on the relationship between the orderingprocess of main chains and that of side chains. We carried out Langevindynamics simulation and found that the initial nucleation processesconsist of three steps: the ordering of ring orientation, the orderingof main-chain vectors, and the ordering of side chains. At the start,the normal vectors of thiophene rings aligned in a very short time,followed by alignment of main-chain end-to-end vectors. The flexibleside-chain ordering took almost 5 times longer than the rigid-main-chainordering. The simulation results indicated that the ordering of sidechains was induced after the formation of the regular stack structureof main chains. This slow ordering dynamics of flexible side chainsis one of the factors that cause anisotropic nuclei growth, whichwould be closely related to the formation of nanofiber structureswithout external flow field. Our simulation results revealed how thecombined structure of the planar and rigid-main-chain backbones andthe sparse flexible side chains lead to specific ordering behaviorsthat are not observed in ordinary linear polymer crystallization processes. [ABSTRACT FROM AUTHOR]

Our study is focused on the relationship between the structural coherence and intrinsic carrier transport in a regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofiber, particularly in an isolated nanofiber, formed in various ratios of good and poor solvent mixtures. The P3HT nanofiber, which is formed in solvent mixtures, had a whisker structure with the length of several μm, the height decreased from 9 to 2 nm as estimated by scanning force microscope observation, and the structural coherent length along the longitudinal axis increased from 40 to 59 Å as determined by x-ray-diffraction measurement, with increasing ratio of the good solvent. The I-V characteristics measured by the four-probe method showed that the activation energy of hopping conduction, which was considerably related with the structural disorder, decreased with increasing ratio of the good solvent. Moreover, the field-effect-transistor characteristics of the nanofiber showed that the carrier mobility increased with increasing ratio of the good solvent, and the nanofiber formed under the good-solvent-rich condition showed the mobility from 3.8×10-2 to 5.6×10-2 cm² V-1 s-1. The tendency of the mobility to increase has been explained on the basis of the change in the structural coherent length and thermal activation energy, assuming the model that regarded the nanofiber as a one-dimensional array of electronically coherent regions and incoherent defects, and hence the relationship between the structural coherence and carrier transport has been clarified. [ABSTRACT FROM AUTHOR]

The critical phenomena of double percolation on polybutadiene (PB)/polyethylene glycol (PEG) blends loaded with poly-3-hexylthiophene (P3HT) nanofibers is investigated. P3HT nanofibers are selectively localized in the PB phase of the PB/PEG blend, as observed by scanning force microscopy (SFM). Moreover, double percolation is observed, i.e., the percolation of the PB phase in PB/PEG blends and that of the P3HT nanofibers in the PB phase. The percolation threshold (φcI) and critical exponent (tI) of the percolation of the PB phase in PB/PEG blends are estimated to be 0.57 and 1.3, respectively, indicating that the percolation exhibits two-dimensional properties. For the percolation of P3HT nanofibers in the PB phase, the percolation threshold (φcII) and critical exponent (tII) are estimated to be 0.02 and 1.7, respectively. In this case, the percolation exhibits properties in between two and three dimensions. In addition, we investigated the dimensionality with respect to the carrier transport in the P3HT nanofiber network. From the temperature dependence of the field-effect mobility estimated by field-effect transistor (FET) measurements, the carrier transport was explained by a three-dimensional variable range hopping (VRH) model. [ABSTRACT FROM AUTHOR]

We investigated the electrical properties of a composite film loaded with semi-conductive poly(3-hexylthiophene) (P3HT) nanofibers dispersed in poly(styrene-b-butadiene-b-styrene) (SBS). This structure can be regarded as the hybrid of SBS matrix with elastic mechanical properties and P3HT nanofibers with semiconducting properties. The P3HT nanofibers were embedded in the fingerprint pattern of microphase-separated SBS, as observed by scanning force microscopy. Furthermore, the electrical conductivity and field-effect mobility of the composite films were evaluated. The field-effect mobility was estimated to be 6.96 × 10−3 cm2 V−1 s−1, which is consistent with the results of previous studies on P3HT nanofibers dispersed in an amorphous polymer matrix including poly(methyl methacrylate) and polystyrene, and we found that the P3HT nanofiber network was connected in the SBS bulk matrix. The film was stretchable; however, at elongation by two times, the nanofiber network could not follow the elongation of the SBS matrix, and the conductivity decreased drastically. The field-effect transistor of this film was operated by bending deformation with a radius of curvature of 1.75 cm, though we could not obtain an off-state and the device operated in a normally-on state. [ABSTRACT FROM AUTHOR]

We investigated the field-effect mobility of regioregular poly(3-hexylthiophene) (P3HT) and N , N ′-ditridecyl-3,4,9,10-perylenetetracarboxyl diimide (PTCDI-C13) nanofibers composited in poly(methyl methacrylate) (PMMA) with varying P3HT/PMMA or PTCDI-C13/PMMA ratio, solvent species, and doping concentration by fabricating the field effect transistor (FET) of these composite films. Both composite films functioned as a p- or n-type semiconducting layer of FET, and the apparent field-effect mobility gradually increased with increasing P3HT or PTCDI-C13 ratio, and was estimated to be about 4.7 × 10 −3 cm 2 V −1 s −1 (P3HT nanofiber/PMMA composite, P3HT weight ratio = 10%) and 2.0 × 10 −5 cm 2 V −1 s −1 (PTCDI-C13 nanofiber/PMMA composite, PTCDI-C13 weight ratio = 20%). In addition, a pn junction between P3HT nanofiber/PMMA and PTCDI-C13 nanofiber/PMMA composite films was fabricated to examine the rectifying effect. The rectifying effect was obtained and an appropriate diode region was observed in the forward current with the ideal factor n of 2.30. The rectifying effect can be derived by a simple fabrication method, i.e., simply pasting n- and p-type flexible films together, which gives us a novel methodology for fabricating flexible semiconducting devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] Insulator surface modification of FET using P3HT nanofibers was investigated. [•] The FET of nanofiber mat on fluoro-modified surface was in a normally-on state. [•] The mobility was larger than that on other modified surface. [•] The mobility of isolated nanofibers on fluoro-modified surface was much larger. [Copyright &y& Elsevier]