Effects of second dopants on electrical conductivity and thermopower of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-filled carbon black

• The conductive PEDOT:PSS-filled carbon black composites are investigated.
• Second dopant has a significant effect on the electrical conductivity of composites.
• A slight influence of second dopant is found on thermopower of composites.
• Dimethyl sulfoxide doped composite presents the largest power factor.

The electrical conductivity and thermopower of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) filled carbon black (CB) were investigated with dimethyl sulfoxide, ethylene glycol, and 1-butyl-3-methylimidazolium tetrafluoroborate as second dopants. The electrical conductivity (608 S m−1) and thermopower (6.0 μV K−1) of PEDOT:PSS-filled CB increased three and six times over pure CB, respectively. Dimethyl sulfoxide exhibits a better effect on the enhancement of electrical conductivity (2034 S m−1), while 1-butyl-3-methylimidazolium tetrafluoroborate has a greater influence on thermopower (8.3 μV K−1) of PEDOT:PSS-filled CB. Electrical conductivity and thermopower depend on second dopant contents and 30 vol.% dopants gain the highest power factor (0.75–0.10 μW m−1 K−2) for PEDOT:PSS-filled CB based on electrical conductivity and thermopower. The second dopants represent a great effect on the electrical conductivity of PEDOT:PSS-filled CB, but less influence on thermopower.

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