Influence of the thermal contact resistance on the thermoelectric property of PANI/Ag nanocomposites

In this paper, the experimental electrical conductivity and the thermal conductivity of PANI/Ag nanocomposites are firstly measured, both of which increases with the increase of the Ag nanoparticle content while the percolation phenomenon is only exhibited clearly for the electrical conductivity. The electrical conductivity increase much fast than that of the thermal conductivity, which leads to the ratio between the electrical and thermal conductivities enlarged about 100 times with the increase of the filler content. To reveal the underlying mechanism of the different percolation threshold for the electrical and thermal conductivities, the thermal contact resistance between Ag nanoparticles is calculated with our improved Agari's model. It reveals that: with the increase of the filler content, the thermal contact resistance should be responsible for the different increasing tendencies or percolation threshold of the electrical and thermal conductivities. The measurement of the Seebeck coefficient shows that the incorporation of Ag nanoparticles in the PANI matrix has little effect on the Seebeck coefficient of PANI. The large figure-of-merit enhancement of the PANI/Ag nanocomposites should result from the larger percolation threshold of the thermal conductivity than that of the electrical conductivity due to the thermal contact resistance.