Thermoelectric Properties of Hybrid Thin Films of PEDOT-PSS and Silver Nanowires

We report the thermoelectric (TE) properties of organic-inorganic hybrid thin films composed of conductive polymer, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS), and inorganic silver nanowire (AgNW). Two kinds of AgNW with different wire length, 3 mu m and 27 mu m, were used in this study. The AgNW/PEDOT-PSS hybrid films showed an increase in electrical conductivity (sigma) with increase in AgNW concentration. The maximum value of sigma obtained in this system was ca. 10,000 S cm(-1). The films containing long AgNWs (L-AgNWs) showed higher sigma relative to short AgNWs (S-AgNWs) at given concentration, which results from the fact that longer nanowires can easily form a percolated structure. The formation of a percolated structure was confirmed by scanning electron microscopy (SEM) observation. On the other hand, the Seebeck coefficient (S) of the hybrid films showed the opposite dependence on AgNW concentration. This decrease in S with increasing AgNW concentration is probably because of increase in carrier number due to the AgNWs. These results suggest that the presented organic-inorganic hybrid system is one example where the electrical conductivity and TE properties can be tuned by use of a nanocomposite.