High-performance Y5–SWCNT thermoelectric alloy produced via pre-crystallization filtration†

Organic thermoelectric materials have attracted tremendous attention owing to their heat-harvesting capability, solution processability, and mechanical flexibility. Moreover, molecular engineering allows the facile and convenient tuning of the thermal conductivity and conductivity of organic materials, thereby generating high-performance thermoelectric modules. A model featuring a blend of organic small molecules (OSMs) with single-walled carbon nanotubes (SWCNTs) is presented herein as an effective protocol to produce solution-processed thermoelectric materials with high performances and well defined structures. A fascinating aspect of organic conjugated systems is the dependence of their thermoelectric characteristics on their molecular packing and self-assembly, and the latter can be determined using composite preparation techniques. Herein, we synthesized a pre-crystallization filtration-derived Y5-SWCNT alloy that exhibits high thermoelectric performances. Using the method proposed herein, OSMs were purified and well-retained in the alloy and reduced material loss, thereby contributing to thermoelectric metrics. The as-fabricated pellet-type Y5-SWCNT alloy displayed a Seebeck coefficient of 54.53 μV K⁻¹ and a high power factor of up to 257.52 μW m⁻¹ K⁻². Extremely high mechanical stability was achieved using our method, as demonstrated through multi-cycle bending tests. Based on the inherent flexibility of SWCNTs, we extended the applicability of our method to the preparation of other common OSM/SWCNT systems and demonstrated profoundly improved thermoelectric performances compared with conventional blending methods.