Interfacial enhancement effect of graphene quantum dots on PEDOT:PSS/single-walled carbon nanotubes thermoelectric materials

In the present study, Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS), with the incorporation of graphene quantum dot (GQD)-coated single-walled carbon nanotubes (SWCNTs), has been used in the preparation of PEDOT:PSS/SWCNTs/GQDs thermoelectric films (PSG). The effect of SWCNTs/GQDs (as a nanofiller) on the microstructure and thermoelectric properties of the composite films has been especially investigated. It was observed that the addition of GQDs will induce a phase separation between PEDOT and PSS. Furthermore, the enhanced interfacial bonding induced a microstructure ordering and an accelerated transport of carriers. The in-plane electrical conductivity and Seebeck coefficient of the obtained film reached 1036 S•cm−1 and 13.8 μV•K−1, respectively, for 1 wt% of SWCNTs/GQDs. These results gave a high power factor (PF) of up to 19.9 µW•m−1•K−2, which is about six times as high as for pristine PEDOT:PSS and also higher than that of PEDOT:PSS/SWCNTs. The obtained maximum ZT reaches 3.22 × 10−3 with high PF value and low in-plane thermal conductivity. The present research provided a new strategy for developing high performance organic thermoelectric materials.