Radical‐Mediated Dispersion Breaks Aggregation Limits in Carbon Thermoelectrics

ABSTRACT

Carbon‐based materials, particularly single‐walled carbon nanotubes (SWCNTs), are promising candidates for flexible thermoelectric applications due to their excellent electrical conductivity and mechanical robustness. However, severe self‐aggregation of SWCNTs leads to suboptimal and degraded thermoelectric performance. Conventional dispersion strategies have proved largely ineffective in overcoming this limitation. Here, we present a pioneered radical‐mediated dispersion (RMD) strategy, enabled by a rationally designed small molecule, OTN, which incorporates a donor‐acceptor conjugated backbone and pendant free‐radical terminals. The RMD strategy mechanism functions through dual interactions: The donor‐acceptor backbone enhances π‐interactions with SWCNTs, while the pendant radicals facilitate radical‐radical interactions to further suppress nanotube aggregation. This synergistic molecular design enables OTN‐SWCNT hybrid films to achieve a high power factor of 30.1 µW cm ⁻¹ K ⁻² , far exceeding previous reports, while maintaining excellent free‐standing mechanical flexibility. Furthermore, a nine‐leg thermoelectric device assembled from these films delivers a normalized power density of 0.653 µW cm ⁻² K ⁻² , representing one of the best performances for CNT‐based thermoelectrics to date. This pioneering molecular design and derived innovative RMD strategy overcomes the long‐standing aggregation of SWCNTs and is anticipated to open new avenues for advancing carbon‐based thermoelectric materials toward practical, flexible energy‐harvesting applications.