High‐Power‐Density and Excellent‐Flexibility Thermoelectric Generator Based on All‐SWCNTs/PVP Composites

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-07, Vol.20 (27), p.e2306125-n/a
• Main Authors: Zhang, Lin, Shang, Hongjing, Zou, Qi, Feng, Changping, Gu, Hongwei, Ding, Fazhu
• Format: Article
• Language: English
• Subjects: Bonding strength; Composite materials; Electron transfer; Electron tunneling; Flexibility; Hydrogen bonds; Modules; n‐type unconjugated polymer/SWCNT; Oxygen atoms; Polymers; PVP; Single wall carbon nanotubes; Temperature gradients; thermoelectric; Thermoelectric generators; Thermoelectricity
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202306125

Flexible polymer/single‐wall carbon nanotube (SWCNT) composites are a vital component for wearable/portable electronics, but the development of their n‐type counterpart is laggard. Furthermore, little attention is paid to the interaction between SWCNT and polymers, especially the unconjugated polymers, as well as the conversion mechanism of conduction characteristics. Here, the n‐type flexible SWCNTs/Polyvinyl Pyrrolidone (PVP) films are successfully fabricated, where the oxygen atoms in PVP interacted with SWCNT via hydrogen bonds, which can lower the energy barrier of electron tunneling, providing the pathway for the electron transfer. Furthermore, with the increasing synthesis temperature, the hydrogen bonds strengthened and the thermal activation energy further improved, both of which enhanced the electron‐donating ability of PVP, resulting in a high‐power‐factor value of 260 µW m−1 K−2. Based on the optimized SWCNTs/PVP films, a thermoelectric module is assembled, which achieved a power density of 400 µW cm−2 at a temperature difference of 56 K, coupled with excellent flexibility, showing a less than 1% variation of resistance after 5000 bending cycles. It shows the highest output‐performance and the best flexibility among the reported SWCNT‐based thermoelectric modules. This work provides significant insights into the interaction mechanism and performance optimization of hybrid thermoelectric composites, based on SWCNTs/unconjugated polymers. N‐type single‐wall carbon nanotubes (SWCNTs)/Polyvinyl Pyrrolidone (PVP) composite films with high thermoelectric performance are fabricated by the chemical solution method. Using these films, a thermoelectric module with all‐SWCNTs/PVP composites is assembled, which shows a power density of 400 µW cm‐2 at a temperature difference of 56 K, and there is a less than 1% variation of resistance after 5000 bending cycles, showing excellent flexibility.