Toward improved trade-off between thermoelectric and mechanical performances in polycarbonate/single-walled carbon nanotube composite films

Polymer thermoelectric (TE) composites have witnessed explosive developments in recent years, arising from their promising prospect for lightweight flexible electronics and capability of harvesting waste-heat. In sharp contrast with intrinsically conducting polymers (CPs), the insulating thermoplastics have seldom been employed as the matrices for flexible TE composites despite their advantages of low costs, controllable melt-flowing behaviors and excellent mechanical properties. Here, we report flexible films of polycarbonate/single-walled carbon nanotube (PC/SWCNT) composites with improved trade-off between TE and mechanical performances. The SWCNTs with 1D nanostructure were dramatically aligned by PC melt-flowing under hot-pressing in the radial direction. The composite maximum power factor reaches 4.8 ± 0.8 μW m−1 K−2 at 10 wt% SWCNTs in the aligned direction, which is higher than most previously reported thermoplastics-based TE composites at the same SWCNT loading and even comparable to some intrinsically CPs and their composites. In addition, these composites display significantly higher tensile modulus and strength than CPs and their composites. This study paves an effective way to fabricate flexible films of polymer composites with simultaneously high TE and mechanical performances via judicious alignment of SWCNTs in thermoplastic polymers.