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    • Keywords

       

      Quasi-one dimensional conductivity; thermoelectric power; discotic liquid crystals

    • Abstract

       

      We have studied the electrical conductivity of well aligned samples of hexahexylthiotriphenylene (HHTT) in the pure as well as doped states. The dopant used was a small concentration (0.62 mole %) of the electron acceptor trinitrofluorenone (TNF). In the columnar phases, doping causes the AC(1 kHz) conductivity along the columnar axis (σ) to increase by a factor of 107 or more relative to that in undoped samples; σ attains a value of 10−2S/m, which was the maximum measurable limit of our experimental set up. On the other hand, in the isotropic phase doping makes hardly any difference to the conductivity. The frequency dependence of the conductivity has been investigated. The DC conductivity of doped samples exhibits an enormous anisotropy, σ/σ ≥ 1010, which is 7 orders higher than that reported for any liquid crystalline system, and, to our knowledge, the largest observed in an organic conductor.

      We also report the first thermoelectric power studies on these ‘molecular wires’. The sign of the thermoelectric power is in conformity with the expected nature of the charge carriers, namely, holes.

    • Author Affiliations

       

      V S K Balagurusamy1 S Krishna Prasad1 S Chandrasekhar1 2 Sandeep Kumar1 M Manickam1 C V Yelamaggad1

      1. Centre for Liquid Crystal Research, P.B. No. 1329, Jalahalli, Bangalore - 560 013, India
      2. Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore - 560 064, India
    • Dates

       
  • Pramana – Journal of Physics | News

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