Study of effect of coupling geometry in improvement of thermoelectric properties of polyaniline molecular junction

In this paper, we investigate thermoelectric properties of polyaniline molecular junction for three different coupling geometries of the coupling of the molecule to the electrodes including para (symmetric), meta and ortho (asymmetric) configurations. The selected electrodes are three dimensional and face center cubic (FCC) similar to the experimental works. The nonequilibrium Green function formalism is used to obtain thermoelectric coefficients in nonlinear response regime. The Hamiltonian of the system is described by tight binding method. The results show, in asymmetric coupling, the electrical conductance and thermal conductance decrease whereas thermopower and figure of merit show better behavior and increase in meta and ortho configurations. Therefore asymmetry in polyaniline molecular junction causes an improvement in thermoelectric efficiency of the junction that is a desirable result for scientists. On the other hand, the oscillating behavior of thermopower indicates the kind of carriers and the place of molecular energy levels relative to the Fermi energy change during the thermal tunneling.