Quasi-one dimensional electrical conductivity and thermoelectric power studies on a discotic liquid crystal

V. S.K. Balagurusamy, S. Krishna Prasad, S. Chandrasekhar, Sandeep Kumar, M. Manickam, C. V. Yelamaggad

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72 Scopus citations

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; σPLL 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, σPRP≥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.

Original languageEnglish
Pages (from-to)3-11
Number of pages9
JournalPramana - Journal of Physics
Volume53
Issue number1
DOIs
StatePublished - Jul 1999
Externally publishedYes

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