Boosting the Thermoelectric Performance of the Doped DPP‐EDOT Conjugated Polymer by Incorporating an Ionic Additive

The thermoelectric (TE) performance of organic materials is limited by the coupling of Seebeck coefficient and electrical conductivity. Herein a new strategy is reported to boost the Seebeck coefficient of conjugated polymer without significantly reducing the electrical conductivity by incorporation of an ionic additive DPPNMe3 Br. The doped polymer PDPP-EDOT thin film exhibits high electrical conductivity up to 1377 ± 109 S cm-1 but low Seebeck coefficient below 30 µV K-1 and a maximum power factor of 59 ± 10 µW m-1 K-2 . Interestingly, incorporation of small amount (at a molar ratio of 1:30) of DPPNMe3 Br into PDPP-EDOT results in the significant enhancement of Seebeck coefficient along with the slight decrease of electrical conductivity after doping. Consequently, the power factor (PF) is boosted to 571 ± 38 µW m-1 K-2 and ZT reaches 0.28 ± 0.02 at 130 °C, which is among the highest for the reported organic TE materials. Based on the theoretical calculation, it is assumed that the enhancement of TE performance for the doped PDPP-EDOT by DPPNMe3 Br is mainly attributed to the increase of energetic disorder for PDPP-EDOT.