Flexible Thermoelectric Device Based on Poly(ether-b-amide12) and High-Purity Carbon Nanotubes Mixed Bilayer Heterogeneous Films

Thermoelectric (TE) generators are an appealing, ecofriendly energy harvesting technology capable of converting temperature gradients into electricity. Carbon nanotube (CNT) filled organic composites typically offer the best potential for making cheaper TE materials. In this study, a block copolymer poly(ether-b-amide12) (PEBA) with excellent flexibility and mechanical properties was used to fabricate TE materials via blending CNTs. After doping PEBA with lithium chloride (PEBA-Li+), two types (p-type and n-type) of CNT filled PEBA-Li+ (CNT-PEBA-Li+) TE composites were obtained via a simple one-step casting method. Here, the n-type CNT is prepared by diethylenetriamine doping treatment of the pristine CNT (p-type). The resultant TE materials exhibited a bilayer heterogeneous (BH) structure comprised of a thermally nonconductive layer and a conductive layer. The Seebeck coefficient (S) and electrical conductivity (σ) (under the application of temperature gradient 20 K) for the obtained p-type CNT-PEBA-Li+ bilayer heterogeneous film (BHF) are 36.88 μV/K and 456 S/m and for the n-type CNT-PEBA-Li+ BHF are −33.25 μV/K and 492 S/m, respectively. We constructed this novel TE device by integrating p- and n-type elements. The results showed that generated TE voltages for the module made of three TE couples were able to reach 120 mV for a temperature gradient of 60 K. The TE device construction was more efficient and simpler due to the BH structure, as only two BHF types were needed and no thermal insulating layer was necessary. In addition, our TE device is flexible throughout the entire structure. These novel flexible TE composites may benefit future organic TE materials research and promote the application of flexible and wearable power-conversion devices for next-generation power generators and waste-heat-recovery systems.