Great Enhancement in the Seebeck Coefficient and Thermoelectric Properties of Solid PEDOT:PSS Films Through Molecular Energy Filtering by Zwitterions

Organic thermoelectric (TE) materials are considered as the next-generation TE owing to their merits including high mechanical flexibility, low cost, abundant elements, and nontoxicity. However, Seebeck coefficient is lower than that of inorganic counterparts by around one order magnitude, thus they have a dimensionless figure merit (ZT) value. Herein, significant enhancement in overall properties poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) most popular polymer adding zwitterion like rhodamine 101 (R101), N-dodecyl-N,N-dimethyl-3-ammonio-1-propane-sulfonate (DDMAP), or 1-(N,N-dimethylcarbamoyl)-4-(2-sulfoethyl) pyridinium hydroxide (DMCSP) reported. In particular, R101 can enhance acid-then-base-treated PEDOT:PSS from 21.2 61.6 μV K−1. The PEDOT:PSS/R101 film exhibit power factor 546 μW m−1 K−2 ZT 0.46 highest for pure organic solid films. ascribed energy filtering induced dipole moment π–π overlapping between conjugated PEDOT:PSS. To distinguish it conventional methods, this method named molecular filtering.