Background: Recently it was for the first time found by us, that completely insulating
Halloysite nanotubes significantly enhance electrical conductivity of PEDOT/PSS films by simply
mixing. Based on this interesting finding highly porous and conductive PEDOT/PSS films hybridized
with the Halloysite nanotubes (HNTs) were prepared. The highly porous morphology of the
hybrid films would hinder thermal conduction, resulting in lower thermal conductivity which is an
advantage for thermoelectric materials. Herein thermoelectric properties of the hybrid films are reported.
Methods: The PEDOT/PSS-HNTs film was prepared using PEDOT/PSS dispersion containing 4wt%
HNTs and 7wt% ethylene glycol (EG). The PEDOT/PSS-HNTs hybrid films were further treated
with ammonium formate (AF) or poly(ethylene glycol) (PEG). The hybrid films were used for measurements
of the thermoelectric performance. The electrical conductivity and Seebeck coefficient
were measured by using a Ulvac ZEM-3 instrument while the thermal conductivity was measured
with a Netzsch LFA 447/2-4/InSb NanoFlash TH Xe flash analyzer and with a Netzsch DSC 204F1
Phoenix differential analyzer, respectively.
Results: The PEDOT/PSS-HNTs film, prepared using PEDOT/PSS dispersion containing 4wt%
HNTs and 7wt% EG, had moderately high electrical conductivity and Seebeck coefficient, i.e., 46 S
cm-1 and 19 μV K-1 at 300 K, respectively, coupled with a quite low thermal conductivity, i.e., 0.16
W m-1 K-1 at 300 K. On the other hand, the PEDOT/PSS-HNTs hybrid films treated with AF or PEG,
also showed similar thermoelectric performance.
Conclusion: All figure of merit (ZT) values of the hybrid films, which were calculated using corresponding
electrical conductivity, Seebeck coefficient and thermal conductivity, were in the range of
1.3-5.5 x 10-3 at 300 K, comparable with those of conventional conducting polymers although the
hybrid films composed of insulating HNTs in 75.5 wt%.