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.