Thermoelectric properties of poly(3,4-ethylenedioxythiophene) with fluorine-containing polyanion as dopant

Abstract

While organic thermoelectric materials are more affordable, flexible, and accessible than their inorganic counterparts, some of these conducting polymers are brittle, impeding their practical application. For addressing this problem, free-standing poly(3,4-ethylenedioxythiophene) (PEDOT) films were synthesized by the galvanostatic polymerization of 3,4-ethylenedioxythiophene in a polymer electrolyte, which consisted of sulfonated polyhydroxy ether with fluorine groups (S-PHEF) dissolved in propylene carbonate. The thermoelectric properties of these films, such as electrical conductivity, Seebeck coefficient, and power factor, were investigated in relation to the polymerization conditions. These included current density, polymerization temperature, and the molecular weight of S-PHEF. The results indicated that the thermoelectric properties of the synthesized films improved by approximately three times when compared with those of the PEDOT films doped by sulfonated polyhydroxy ether without fluorine groups (S-PHE), which were prepared under the same polymerization conditions. Further, it was observed that with an increase in the molecular weight of the dopant polyanion, the quality of the film improved and the charge mobility was enhanced.