‘Metal-Like’ Semiconductors — Role of Mobility in Molecular Conductors
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”.
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.
KeywordsCharge Carrier Concentration Large Temperature Range Axis Conductivity Room Temperature Conductivity Molecular Conductor
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