Synergistic effect of graphene oxide and wet-chemical hydrazine/deionized water solution treatment on the thermoelectric properties of PEDOT:PSS sprayed films

Abstract

The study of thermoelectric materials based on conductive polymers has been reinvigorated because of the hope of improving the thermoelectric properties and, therefore, the thermoelectric efficiency of these materials using nanostructures and nanoengineering. This work, shows the results of flexible thin film composites of graphene oxide and poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), processed by simple and industrially scalable spray coating on polyethylene terephthalate substrates and subsequently treated with hydrazine (Hz) water solution. The power factor of PEDOT:PSS pristine films was found to be 14.3 μWm−1 K−2. On one hand, this power factor was increased to 21.3 μWm−1 K−2 (1.49 times higher) when 3 wt.% of graphene oxide (GO) was present in the PEDOT:PSS film. On the other hand, the power factor (PF) was increased to 35.7 μWm−1 K−2 (2.59 times higher) when a very simple Hz water solution treatment was performed to the neat PEDOT:PSS pristine film. Nevertheless, the best power factor is attained when both, addition of GO and treatment with Hz are performed, obtaining a PF of 47.4 μWm−1 K−2 (3.31 times higher). Furthermore the optimum Hz water solution concentration is reduced by 10 times when GO is present. We report a ZT of 0.084 at 300 K if a thermal conductivity of 0.17 Wm−1 K−1 is assumed. These results remark the importance of studying nanomaterials addition and reduction treatments at the same time when trying to enhance the thermoelectric performance of conductive polymers.