Fullerene polymers: synthesis and properties.

Poly(1,6-heptadiyne)-Based Materials by Metathesis Polymerization.

The most efficient organic solar cells produced to date are bulk heterojunction (BHJ) photovoltaic devices based on blends of semiconducting polymers such as poly(3-hexylthiophene-2,5-diyl) (P3HT) with fullerene derivatives such as [6,6]-penyl-C61-butyric-acid-methyl-ester (PCBM). The need for blending the two components is based on the idea that the exciton diffusion length in polymers like P3HT is only ∼10 nm, so that the polymer and fullerene components must be mixed on this length scale to efficiently split the excitons into charge carriers. In this paper, we show that the BHJ geometry is not necessary for high efficiency, and that all-solution-processed P3HT/PCBM bilayer solar cells can be nearly as efficient as BHJ solar cells fabricated from the same materials. We demonstrate that o-dichlorobenzene (ODCB) and dichloromethane serve nicely as a pair of orthogonal solvents from which sequential layers of P3HT and PCBM, respectively, can be spin-cast. Atomic force microscopy, various optical spectrosco...

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Reappraising the Need for Bulk Heterojunctions in Polymer−Fullerene Photovoltaics: The Role of Carrier Transport in All-Solution-Processed P3HT/PCBM Bilayer Solar Cells

The electrochemical bandgaps for different soluble substituted polythiophenes have been measured by cyclic voltammetry. The effect of substituents on the oxidation/reduction potentials is discussed. Bandgaps obtained by cyclic voltammetry have been found to be in general higher than optical bandgaps. Among regioregular polymers substituted with a phenyl group at position 3 of the thiophene ring, examples are found that give very symmetric voltammograms. Rationalization for this behaviour is discussed from a conformational point of view.

Electrochemical bandgaps of substituted polythiophenes

A review of the current state of understanding of dielectric mixture properties, and approaches to use numerical calculations for their modeling are presented. It is shown that interfacial polarization can yield different non-Debye dielectric responses depending on the properties of the constituents, their concentrations and geometrical arrangements. Future challenges on the subject are also discussed.

Dielectric mixtures: electrical properties and modeling

Photoconductivity in C60 doped polyacetylene derivative

Novel properties of recently developed conducting and insulating polymers and their composites are discussed. Properties of conducting polymer whose main chains are composed of unsaturated /spl pi/-bonds depend strongly on the main chain structure, substituent and also molecular dopants. Various applications of conducting polymers such as electroluminescence (EL) elements, electrolyte capacitors, photoconductors, photovoltaic cells, superconductors and insulators at cryogenic temperature, are discussed by taking effects of molecular dopants such as C/sub 60/ into consideration. A new type of insulating polymer, syndiotactic polypropylene prepared by newly developed metallocene catalysts has been studied and found to exhibit much superior electrical, thermal and mechanical characteristics compared with those of conventional isotactic polypropylene, atactic polypropylene and polyethylene. These excellent characteristics originate from lower crystallinity, smaller spherulites and different crystal lattice than in isotactic polypropylene. Negligible degradation of syndiotactic polypropylene by contact with copper is interpreted in terms of difference of catalysts and suppression of diffusion of copper cation. New types of conducting polymer, insulating polymer composites were prepared. Their conductivity was controlled over more than 10 orders of magnitude by small amounts of a conducting polymer, polypyrrole, which can be interpreted in terms of the percolation model depending on the shape and density of polypyrrole coated insulating polymer particles. Nonlinear current-voltage characteristics were also studied.

Novel properties of new type conducting and insulating polymers and their composites

The electrochemical characteristics of fullerene and its derivative polymers were investigated for use as electrode-active material in rechargeable batteries. These polymer electrodes showed good potential stability and high Coulombic efficiencies in charge-discharge cycles in LiClO4/PC. The charge-discharge capacity of C60O polymer was as high as 340 mAh/g.

https://iopscience.iop.org/article/10.1143/JJAP.36.L1055/pdf

Electrochemical Properties of Fullerene Derivative Polymers as Electrode Materials

Activation phenomena have been observed in the cyclic voltammogram of the film of poly(o-trimethylsilylphenylacetylene) (PTMSiPA) prepared by the solution casting method. Upon electrochemical doping in PTMSiPA the absorption peak in the visible range due to the interband transition is suppressed and a new broad peak appears in the infrared range. Corresponding to this spectral change, the film changes from red to colorless. Spin density evaluated by ESR decreases with electrochemical doping and becomes negligibly small. These doping characteristics have been interpreted in terms of the soliton model just as for the case of nonsubstituted polyacetylene, and the electronic energy scheme of this polymer has been evaluated. A relatively large diffusion coefficient ( 9.2×10-8 cm2/s) of anion dopant ( BF4-) was obtained in this film. It was also found to exhibit high Coulombic efficiency in the charge-discharge characteristics as a secondary battery.

R. Sugimoto

Papers

Photoconductivity in C60 doped polyacetylene derivative

Novel properties of new type conducting and insulating polymers and their composites

Electrochemical Properties of Fullerene Derivative Polymers as Electrode Materials

Electrochemical Characteristics of Stable Polyacetylene Derivatives: Poly(o-trimethylsilylphenylacetylene).

Change in crystal structure of poly(3-alkylthiophene) upon doping