Enhancement of Thermoelectric Performance of DPP based Polymer by Introducing 3,4-Ethylenedioxythiophene Electron-rich Building Block
Donor−acceptor (D−A) type conjugated polymers are promising high performance thermoelectric (TE) materials due to their high carrier mobility, versatile structure and easily tuneable doping level. In this work, we demonstrate significant enhancement in TE performance of diketopyrrolopyrrole (DPP) based D-A conjugated polymers through incorporation of 3,4-ethylenedioxythiophene (EDOT) building block. With one thiophene building block of PDPP-5T was substituted by EDOT, the HOMO level of PDPP-4T-EDOT could be increased and the coplanarity of the conjugated backbone was slightly enhanced, which could facilitate the efficient p-doping of the conjugated polymer. Compared with PDPP-5T, PDPP-4T-EDOT exhibited much higher optimal TE power factor of 298.2 μW m-1K-2 at lower doping level, which is among the highest value for p-type organic thermoelectric materials based on D-A conjugated polymers. The results provie an attractive guidance to design and develop high performance thermoelectric conjugated polymers.