Modeling of the thermoelectric properties of quasi-one-dimensional organic semiconductors

Electrical conductivity sigma, Seebeck coefficient S, electronic thermal conductivity kappa(e) and the thermoelectric figure of merit ZT are investigated theoretically in quasi-one-dimensional (Q1D) organic semiconductors that consist of linear conducting chains of molecules. Two main electron-phonon interaction mechanisms are considered simultaneously. It is shown that under certain conditions the interference between these interactions can occur. As a result, the relaxation time tau(E) as a function of carrier energy takes the form of a Lorentzian peak, which can be rather sharp. The increase of tau(E) leads to the increase of sigma, and the strong dependence of tau(E) on E ensures, simultaneously, the growth of S, at relatively low values of thermal conductivity. Unusually high values of ZT are predicted in such Q1D organic semiconductors.