Enhancement of the Electrical Conductivity and Thermoelectric Performance of Single-Walled Carbon Nanotubes by the Introduction of Conjugated Small Molecules with Cation Groups

Abstract

Organic conjugated small molecules (OCSMs)-based single-walled carbon nanotube (SWCNT) composites have received great attention as potential thermoelectric (TE) materials. The studies show that both π–π and cation−π interactions between OCSMs and SWCNTs obviously improve the TE performance. However, up to now, few OCSMs containing both cation groups and π structures have been combined with SWCNTs as TE materials. In this work, an organic conjugated small molecule with a cation group, (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (PyBOP), was applied to combine with SWCNTs for the first time due to π–π and cation−π interactions between PyBOP and SWCNTs, which are beneficial to improving the electrical conductivity and thermoelectric (TE) performance. The highest electrical conductivity of 3731.5 S cm–1 was achieved for SWCNT/PyBOP, which was 6.59 times larger than that of the pristine SWCNTs, and also one of the highest values for OCSM-based SWCNT composites reported up to date. Among all of the composites, SWCNT/PyBOP displays the maximum power factor of 279.5 μW m–1 K–2 at 403 K. The results demonstrate that the electrical conductivity of SWCNT composites can be dramatically improved by tuning the structure of the OCSMs, which points out a new direction for the rapid development of high-performance TE composite materials.