A Solid Polymer Film with Giant Thermoelectric Properties by Polar Level Splitting with an Organic Donor

Abstract Thermoelectric (TE) materials are significant for sustainable development because they can harvest waste heat into electricity. Here, a treatment of a solid film of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films with a solution of tetrathiafulvalene (TTF) can greatly enhance the Seebeck coefficient while does not affect the electrical conductivity too much, thereby leading to giant enhancement in the overall TE properties. The films can exhibit an electrical conductivity of 2554 ± 161 S cm ⁻¹ and a Seebeck coefficient of 71.0 ± 4.1 µV K ⁻¹ at room temperature. The corresponding power factor is 1285 ± 67 µW m ⁻¹ K ⁻² , and the ZT value can reach 0.80 ± 0.04. The enhancement is attributed to the π–π overlapping between PEDOT and TTF, which causes the splitting of the lower polaron level and lifts the Fermi level of PEDOT.