Postdeposition Processing Influences the Relative Contributions of Electronic and Ionic Seebeck Effects in the Thermoelectric Response of Conducting Polymers

The postdeposition solvent annealing of PEDOT:PSS and PANI–PAAMPSA thin films with dichloroacetic acid (DCA) induces structural modification that dramatically increases the electrical conductivity of these conducting polymers. Herein, we studied how such structural modification impacts the thermoelectric properties of PEDOT:PSS and PANI–PAAMPSA. DCA treatment increases the electronic Seebeck contribution to thermopower relative to the ionic Seebeck contribution for both conducting polymers. Interestingly, DCA treatment also induces a change in the sign of the electronic Seebeck coefficient of PANI–PAAMPSA from negative to positive. This switch in polarity of the Seebeck coefficient is likely to stem from an alteration of PANI’s electronic structure with the morphological reorganization of PANI–PAAMPSA that takes place on DCA annealing. By relating the thermoelectric properties of PEDOT:PSS and PANI–PAAMPSA to the induced structural changes on DCA treatment, design rules have been generated to guide the optimization of thermoelectric response of conducting polymers per device architecture specification and application needs.