A Rational Ternary Design of P3HT/Insulating Polymers–CNTs/P3HT for the Enhanced Thermoelectric Performances

Abstract

ABSTRACT This work shows the design and development of ternary layer thermoelectric composites based on semiconducting polymer P3HT, insulating polymers, and carbon nanotubes. The ternary layer composite film is prepared by a straightforward drop‒cast deposition. The design consists of sandwiching an insulating polymer‒CNTs layer between two layers of a semiconducting polymer P3HT. A systematic investigation is employed by optimizing various features including the type of insulating polymers and CNTs (SWNT vs. MWNT), and doping. The electrical conductivity of the doped ternary composites is improved up to 265 S cm−1, with minimal loss in the Seebeck coefficient, leading to power factors (PF) up to ~30 μW m−1 K−2, however electrical conductivity of single‒layer doped P3HT is only 39.1 S cm−1 with a PF of 7.6 μW m−1 K−2 at room temperature. The enhancement in the TE properties can be ascribed to the formation of more efficient charge transport between the layers due to the rearrangement of the polymer chains and the generation of more junctions at the interface during the sequential layer deposition. The results also reveal that this method gives n‒type materials from intrinsically p‒type P3HT, and it switches to p‒type after doping.