Yifan Lv, Yunfei Cai, J. Dong, Yiyang Li, Baolin Li, Cun‐Yue Guo
Composites of organic small molecules (OSMs) with single-walled carbon nanotubes (SWCNTs) have attracted considerable attention in thermoelectrics, because of their intrinsic flexibility and tunable energy levels. In this work, thieno[2′,3′:4,5]thieno[3,2- b ]thieno[2,3- d ]thiophene (TTA)-based OSMs including 2,6-bis(benzo[ b ]thiophen-2-yl)thieno[2′,3′:4,5]thieno[3,2- b ]thieno[2,3- d ]thiophene (2BT-TTA), 2,6-bis(benzo[ b ]furan-2-yl)thieno[2′,3′:4,5]thieno[3,2- b ]thieno[2,3- d ]thiophene (2BF-TTA), and 2,6-bis(4-octylphenyl)thieno[2′,3′:4,5]thieno[3,2- b ]thieno[2,3- d ]thiophene (2(C 8 Ph)-TTA) were designed and synthesized to construct flexible thermoelectric films. The modulation of molecular energy levels in 2(C 8 Ph)-TTA facilitates effective p-type doping, while the alkylphenyl side chains enhance intermolecular π–π interactions with SWCNTs, synergistically improving the thermoelectric performance of the composite films. The optimized composite film containing 10 wt % 2(C 8 Ph)-TTA exhibited the best thermoelectric performance, achieving a power factor of 372.66 ± 4.12 μW m –1 K –2 at room temperature, along with high thermal stability and flexibility. Furthermore, a thermoelectric generator consisting of seven pairs of p-n legs of this composite and n-type SWCNT film generates a maximum power density output of 26.64 μW g –1 at Δ T = 60 K. This study provides new insights into the design of high-performance OSM/SWCNT thermoelectric materials.