Fujita, TatsumaTatsumaFujitaMatsuda, MegumiMegumiMatsudaLin, Po-ShenPo-ShenLinChou, Che-AnChe-AnChouLin, Jhih-MinJhih-MinLinCHENG-LIANG LIUHigashihara, TomoyaTomoyaHigashihara2025-07-312025-07-312025-06-2900219797https://www.scopus.com/record/display.uri?eid=2-s2.0-105009596117&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/730829This study systematically investigated the effect of phenylalkyl side chains on the thermoelectric (TE) properties of polythiophene (PT) derivatives/single-walled carbon nanotube (SWCNT) nanocomposite films. A series of six regioregular poly[3-(phenylalkyl)thiophene]s (P3PATs) bearing phenylalkyl side chains with different methylene spacer lengths (m = 2, 3, 4, 6, 8, and 12), designated P3PET, P3PPT, P3PBT, P3PHT, P3POT, and P3PDT, respectively, were synthesized via Kumada–Tamao–Corriu catalyst-transfer polymerization. Spectroscopic analyses revealed efficient energy transfer from P3PATs to SWCNTs, facilitated by strong polymer–CNT interactions, as evidenced by red-shifted ultraviolet–visible absorption and substantial photoluminescence quenching. Morphological characterization demonstrated that longer phenylalkyl side chains promoted more effective wrapping and debundling of SWCNTs, resulting in smaller bundle diameters and better dispersion. Among the series, the P3PDT/SWCNT nanocomposite achieved a maximum power factor of 165 ± 22 μW m−1 K−2, ∼2.5 times higher than that of poly(3-hexylthiophene)/SWCNT nanocomposites. These results highlight the critical role of phenylalkyl side chains and their length in modulating P3PAT/SWCNT interactions, nanocomposite morphologies, and TE performance. This work offers valuable guidance for the molecular engineering of high-performance TE nanocomposites via strategic side-chain design of PTs.falseCarbon nanotubesNanocompositePolythiopheneSide-chain engineeringThermoelectricsjournal article10.1016/j.jcis.2025.1382992-s2.0-105009596117