High-performance ladder-type conjugated polymer/carbon nanotube nanocomposites blended with elastomers for stretchable thermoelectric thin films

Stretchable thermoelectric thin films have attracted considerable attention due to their prospective applications in wearable electronics. Nevertheless, targeted resolutions are required for persistent challenges such as the increased resistance and diminished electrical conductivity under strain. The present study focuses on the development of high-performance thermoelectric nanocomposites via the blending of thienyl-phenylene-thienylene-phenylene-thienyl (TPT) nonacyclic fused ring-based conjugated polymers with single-walled carbon nanotubes (CNTs). To disperse the CNTs, three TPT-based ladder-type random conjugated copolymers featuring distinct acceptor units are investigated, namely (i) thieno[3,4-c]pyrrole-4,6(5H)-dione (TPD), (ii) diphenylquinoxaline (QX), and (iii) thieno[3,4-b]thiophene (TT). Notably, the highly planar backbone structure of TPT-TT efficiently wraps around the surfaces of the CNTs, thus facilitating their uniform dispersion within the nanocomposite film. Consequently, the TPT-TT/CNT nanocomposite exhibits superior thermoelectric properties, including a power factor (PF) of up to 678.8 μW m⁻¹ K⁻². In addition, stretchable thermoelectric thin films are fabricated on a poly(dimethylsiloxane) (PDMS) substrate by incorporating various amounts of the styrene-ethylene-butylene-styrene (SEBS) elastomer into the TPT-TT/CNT nanocomposite. The ternary TPT-TT/CNT/SEBS25 (containing 25 wt% SEBS) nanocomposite film maintains a PF of 372.79 μW m⁻¹ K⁻² (73.2% of its initial value) at 50% strain. The present study introduces a straightforward approach for fabricating stretchable thermoelectric thin films with commendable thermoelectric performance under strains of up to 50% by blending the high-performance ladder-type conjugated-polymer/CNT nanocomposite with SEBS.