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Supramolecular Functionalization for Improving Thermoelectric Properties of Single-Walled Carbon Nanotubes–Small Organic Molecule Hybrids

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journal contribution
posted on 09.11.2020, 20:14 by Jae Gyu Jang, Sun Young Woo, Hwankyu Lee, Eunji Lee, Sung Hyun Kim, Jong-In Hong
Single-walled carbon nanotube (SWCNTs-P)–small organic molecule hybrid materials are promising candidates for achieving high thermoelectric (TE) performance. In this study, we synthesized rod-coil amphiphilic molecules, that is, tri­(ethylene oxide) chain-attached bis­(bithiophenyl)-terphenyl derivatives (1 and 2). Supramolecular functionalization of SWCNTs-P with 1 or 2 induced charge-transfer interactions between them. Improved TE properties of the supramolecular hybrids (SWCNTs-1 and SWCNTs-2) are attributed to increased charge-carrier concentration (electrical conductivity), interfacial phonon scattering (thermal conductivity), and energy difference between the transport and Fermi levels (ETrEF; Seebeck coefficient). SWCNTs-2 exhibited a ZT of 0.42 × 10–2 at 300 K, which is 350% larger than that of SWCNTs-P. Furthermore, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ)-doped SWCNTs-2 showed the highest ZT value of 1.96 × 10–2 at 300 K among SWCNTs-P/small organic molecule hybrids known until now. These results demonstrated that the supramolecular functionalization of SWCNTs-P with small organic molecules could be useful for enhancement of TE performance and applications in wearable/flexible thermoelectrics.