Theoretical Designing of Novel Donor Acceptor Type Copolymer Comprising of Thiophene

Using ab initio band structure results of three novel donor acceptor polymers (A)x PCDT, (B)x PMCT and (C)x PFTh as the input, the electronic structures and conduction properties of their periodic and aperiodic copolymer (AmBnCk)x have been investigated. The method involves using negative factor counting method based on Dean’s negative eigenvalue theorem. In this article, the quasi-one-dimensional Type II staggered copolymers comprising of thiophene units on the basis of the band alignments of the constituent homopolymers were studied. The trends in their electronic structures and conduction properties as a function of (i) block sizes (m, n, k) and (ii) arrangement of the blocks (periodic or aperiodic) in the various copolymer chains are discussed. These trends are important guidelines to the experimentalists for designing novel electrically conducting polymers with tailor made conduction properties.

Electrospinning Graphene – Retention of Anisotropy

Realization of the full potential of 2D nanosheet materials in energy storage and conversion devices requires heterogeneously structured electrodes having good electrical conductivity and large mean free paths for ion diffusion. Electrospinning of anisotropic objects usually obscures this anisotropy because of a large amount of carrier polymer typically required to form fibers. We demonstrate electrospinning of graphene with nearly quantitative retention of flake anisotropy to provide low to moderate density coatings of randomly oriented flakes having very large inter-flake mean free paths for ionic diffusion. Polyvinyl alcohol (PVA) is used as a carrier polymer and yields graphene anisotropy retention over an instability domain wherein electrospinning transitions to electrospraying. Graphene is deposited in polymer-encapsulated films at weight concentrations up to 50%, almost an order of magnitude higher than previously reported. Electrode applications will require at least partial replacement of PVA by electrically conducting polymers, and such polyelectrolytes should also suppress this electrospraying instability. We believe that large-scale electrospinning of graphene nanosheets will accelerate development of 2D materials in the fields of energy storage and conversion, catalysis, and tissue engineering.

On the anomalous optical conductivity dispersion of electrically conducting polymers: ultra-wide spectral range ellipsometry combined with a Drude–Lorentz model

Ultra-wide range spectral range ellipsometry sheds light on the anomalous optical conductivity of conducting polymers.

Conduction Mechanism in Electrically Conducting Polymers

The conduction mechanism in conducting polymers is reviewed and experimental results of temperature dependence of electrical conductivity of PF6 doped polypyrrole in temperature range of 77 to 300 K are discussed. The room-temperature conductivitywas experimentally determined to be 73 ± 3.4 S/m and temperature dependence follows the Mott’s variable range hopping model. The average hopping distance at 298 K was (6.75 ± 0.97) ×10-8 cm. The coefficient of decay of the localized states, the density states at the Fermi level, and the hopping activation energy were calculated to be (3.5±0.51) ×107 cm-1, (1.92 ± 0.83) ×1022 cm-3 eV-1, and 0.040 ± 0.001 eV respectively. KEYWORDS: Electrically Conducting Polymers; Doped Polypyrrole; Temperature Dependence of Conductivity; Hopping Activation Energy; Density of State at Fermi level