Optimization of Benzodithiophene-Based Copolymer and SWCNT Composite Films for Flexible Thermoelectric Generators

Abstract

This study investigates the thermoelectric (TE) properties of a benzodithiophene-based conjugated polymer (PBDTT-DPP) combined with single-walled carbon nanotubes (SWCNTs) for flexible, solution-processable thermoelectric generators (TEGs). Composite films are prepared with varying SWCNT content, achieving optimal performance at 50 wt.% SWCNT. Further optimization through FeCl₃ doping and thermal annealing at 200 °C significantly enhanced the electrical conductivity and overall TE performance. The doped and annealed composite film exhibited a power factor of 135 ± 8 µW mK−2 at 253 °C and a maximum ZT value of 0.17. Spectroscopic and electronic analyses revealed that doping and annealing realigned the energy bands and formed charge-transfer complexes, contributing to improved TE properties. Practical application is demonstrated through the fabrication of flexible, arc-shaped TEGs capable of harvesting energy from curved heat sources. The TEGs achieved a peak power output of 0.66 µW at ΔT = 100 K, showcasing its potential for low-grade waste heat recovery in industrial settings. This research advances the understanding of organic TE materials and offers promising solutions for sustainable energy harvesting from waste heat sources.