High thermoelectric performance of spray-coated Poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) films enabled by two-step post-treatment process

Herein, poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) films with improved thermoelectric properties are fabricated via spray coating followed by a sequential, two-step post-treatment process with ethylene glycol (EG) and a methylammonium iodide (MAI) solution. The EG treatment greatly increases the electrical con-ductivity of the PEDOT-PSS film up to 1752.1 S cm -1, with an unchanged Seebeck coefficient of 15-17 mu V K- 1, while the optimal use of 0.05 M MAI in DMSO/DI water for the second step provides a high power factor of 122.3 mu Wm- 1 K- 2, along with an increased conductivity of 2226.8 S cm -1 and Seebeck coefficient of 22.8 mu V K- 1. Notably, the obtained power factor is among the highest reported for spray-coated polymer-based thermoelectric devices. The performance enhancement is attributed to phase separation of the non-conductive PSS from the PEDOT, the change in chain conformation, the preferential orientation of the PEDOT crystallites, and the manipulation of energy levels. High thermoelectric performance of the as-fabricated PEDOT:PSS on a plastic substrate is established by using a facile proof-of-concept thermoelectric generator to generate a maximum power density of 12.1 nW cm-2. The fabrication approach developed herein provides an essential paradigm for the production of polymer thermoelectric materials with great potential for application in wearable thermoelectric devices.

Automated summary

In this study, poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) films with improved thermoelectric properties were fabricated using spray coating and a sequential two-step post-treatment process. The electrical conductivity of the PEDOT-PSS film was greatly increased up to 1752.1 S cm-1 through EG treatment, while the use of 0.05 M MAI in the second step provided a high power factor of 122.3 mu Wm-1 K-2. The fabrication approach developed in this study provides a paradigm for producing polymer thermoelectric materials with great potential for application in wearable thermoelectric devices.