Thermoelectric transport in ultrathin poly(3,4-ethylenedioxythiophene) nanowire assembly

With the highly ordered structure and thus probably fast carrier transport, one-dimensional (1D) conducting polymers are very promising as organic thermoelectric (TE) materials. Many efforts have been made toward the elucidation of TE transport in polymer nanowires assembly; however, the mechanism for the improvement in thermoelectric property is still far from clear. Here, we systematically investigate the TE transport in 12-nanometer-wide poly(3,4-ethylenedioxythiophene) nanowires (PEDOT NWs) assembly. The iron (III) chloride oxidized PEDOT NWs shows high electrical conductivity σ (∼540 S/cm), an enhanced Seebeck coefficient S that is 2.6 times of that of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and tuned power factor (PF∼35.8 μW/m·K2). To the best of our knowledge, it outperforms the TE performance of all reported 1D conducing polymers based films. More importantly, we carefully interpret the origin of σ and S enhancements in PEDOT NWs-based films. The high σ mainly results from the significant increment of carrier mobility μ, which is mainly due to preferred edge-on orientation and high crystallinity of PEDOT chains. The large S in PEDOT NWs-based films stem from the sharp feature of the density of states at Fermi level.