The thermoelectric behaviour of disordered systems

Abstract

A very general approach is used to derive formulae for the thermopower and the electronic thermal conductivity in terms of the electrical conductivity taken as a function of energy [sgrave](E). It depends on two assumptions: (1) the electrical conductivity can be properly considered to be the sum of processes at specific energies, justifying the expression [sgrave](E), and (2) each electron carries with it an energy E when it moves. The resulting formulae are particularly useful for disordered systems, where the transport mechanisms are poorly understood, and for which different modes of behaviour may occur at different energies, such as hopping in localized states or diffusive motion in extended states.