Electrical conduction in dynamically disordered synthetic semiconductors

Abstract

The two low-dimensional synthetic semiconductors (Et4N)(Ni(dmit)2) and (Et4N)0.5(Pd(dmit)2) exhibit an anomalous temperature dependence of their electrical conductivity: ln( sigma ) varies as T-12/. In the literature, such behaviour is associated with disorder, while in the above-mentioned compounds static disorder is absent. The authors show that in these compounds the disorder is dynamic. The spread in values of the transfer integrals due to thermal vibration of the anions is sufficiently large to shift a significant number of states into the gap region of the rigid lattice and to localise the eigenstates 'dynamically'. With this approach, they reproduce the T-12/-dependence of ln( sigma ), irrespective of the electronic dimensionality of the system.