Simultaneous increase in conductivity and Seebeck coefficient in a polyaniline/graphene nanosheets thermoelectric nanocomposite

Polyaniline/graphene nanosheets (PANI/GNs) thermoelectric (TE) bulk composite pellets and films have been prepared with PANI to GNs weight ratios ranging from 4:1 to 1:1. Their structure and morphology have been investigated by Raman spectroscopy, thermogravimetric analysis and field emission scanning electron microscopy. The TE properties of the pellets and films were measured at room temperature. As the weight ratio of PANI to GNs decreased from 4:1 to 1:1, both the electrical conductivity and the Seebeck coefficient of pellets and the films increased. This was attributed to a substantial increase in carrier mobility while carrier concentration was not significantly changed. As a result, the power factor of the pellets and films increased from 0.64 to 5.60 and 0.05 to 1.47 μW m−1 K−2, respectively. This is the first time the TE properties of PANI/GNs nanocomposites were reported.