Enhanced Thermoelectric Performance of Vapor Phase Polymerized PEDOT‐Tos via Ionic Liquid Post‐Treatment

Abstract Thermoelectric (TE) materials can effectively convert waste heat into electricity, which is a key technology for solving energy shortage problems. Poly(3,4‐ethylenedioxythiophene) (PEDOT), as a promising energy conversion material, has attracted much attention due to its easy doping, low toxicity, and high flexibility. However, the TE performance of PEDOT still needs further improvement. In this work, vapor phase polymerization (VPP) and ionic liquid (IL) post‐treatment are combined to obtain high‐performance PEDOT film. It is demonstrated that by varying the polymerization conditions, the optimal conductivity and Seebeck coefficient of PEDOT‐Tos are 947 S cm⁻¹ and 18.3 µV K⁻¹, respectively. Furthermore, after treatment with 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIM BF₄), its power factor can be further enhanced to a maximum value of 154.58 µW m⁻¹ K⁻², which is 4.9 times higher than that without treatment (31.67 µW m⁻¹ K⁻²). The enhanced TE performance of PEDOT is largely due to changes in doping levels and morphology, which have been confirmed through different characterization methods. These results will contribute to the preparation of high‐performance PEDOT films by the VPP method.