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‘Metal-Like’ Semiconductors — Role of Mobility in Molecular Conductors

  • Arthur J. Epstein
Part of the Nato Conference Series book series (NATOCS, volume 1)

Abstract

In recent years, much work has focused on understanding charge transport in molecular conductors.1–4 There are many similarities in the temperature (T) dependence of the conductivity (a) of many quasi-one-dimensional (1-D) materials which contain parallel segregated chains of large, planar, open-shell molecules, such as TCNQ-(TCNQ = 7,7,8,8-tetracyano-p-quinodimethane).5 The g(T) behavior for these molecular conductors falls into three general classes:
  1. I.

    Materials with strongly activated a, such as (alkali+)-(TCNQ-).6 In general, σ(295K) is in the range of 10-66-100 Ω-1cm-1. These materials are usually characterized as “semiconductors”.

     
  2. II.

    Those systems with a broad weak maximum, σm, in the temperature dependence of their dc conductivity at a temperature Tm. For these systems usually σm/σ(295K) ≲ 2 and σ(295K) ~ 100 Ω-1cm-1. The a versus T curves for these systems generally show negative curvature (d2σ/dT2 < 0) over a large temperature range around Tm. This class is typified by the a versus T behavior of (NMP)(TCNQ)7 (NMP = N-methylphenazinium), Figure la. Numerous prior models have been used to characterize σ(T) for this class of materials (see below). It is shown below how this broad group of materials can be understood in terms of ‘metal-like’ semiconductors with a large strongly T-dependent mobility.

     

Keywords

Charge Carrier Concentration Large Temperature Range Axis Conductivity Room Temperature Conductivity Molecular Conductor 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1979

Authors and Affiliations

  • Arthur J. Epstein
    • 1
  1. 1.Xerox Webster Research CenterRochesterNew YorkUSA

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