High performance of p-type and n-type thermoelectric materials based on liquid crystal mixture and single-walled carbon nanotube composites

Organic small molecule (OSM)/single-walled carbon nanotube (SWCNT) composites are promising thermoelectric (TE) materials, however the low Seebeck coefficient (S) limits their application. Here, a eutectic nematic mixture E7 was chosen to improve the S and power factor (PF) of SWCNTs by energy filtering process. As a result, the introduction of E7 can significantly decrease the carrier concentration of the composite with the mobility greatly enhanced, leading to an improved S (2.23 times of that of pristine SWCNTs). At the mass ratio of 1:0.25, the p-type SWCNT/E7 composites displayed a maximum PF of 428.59 ± 58.15 μW m−1 K−2, which was one of the highest values among OSM-based TE composites reported so far. In addition, after doped with triethylamine, SWCNT/E7 can convert from p-type to n-type. This study demonstrated that SWCNT/E7 composites showed great promise in TE materials and opened up a new avenue for the development of TE materials.