Influence of the incorporation of small conjugated molecules on the thermoelectric properties of carbon nanotubes

Abstract Small-bundled single-walled carbon nanotube (SSWCNT) nanocomposite films made with various small molecules were facilely fabricated using the micronizing mill process. Finely dispersed small molecules in the SSWCNT film can effectively reduce the in-plane thermal conductivity of the nanocomposite due to π-π interactions. Furthermore, the micronizing mill process ensures the uniform distribution of the small molecules and the SSWCNTs in the nanocomposite film without any damage or deformation of the SSWCNT structure. Moreover, the influence of the shape of the small molecules on the thermoelectric properties of SSWCNT nanocomposite was systematically investigated. The thermoelectric properties of the pyrene/SSWCNT nanocomposite were found to have been greatly improved by the planar pyrene molecules with a slightly increased electrical conductivity of 978.6 S cm −1 and a significantly decreased in-plane thermal conductivity of 13.5 W m -1  K -2 . The evaluated ZT value of the pyrene/SSWCNT nanocomposite was 4.4 × 10 −3 and is about 20 times higher than that of the pristine SSWCNT nanocomposite. A planar-type thermoelectric generator (TEG) consisting of 20 legs was also fabricated using this pyrene/SSWCNT nanocomposite. The TEG showed an open circuit voltage of 20 mV and a short circuit current of 350 μA, resulting in a maximum output power of 1.5 μW at ΔT  = 20 °C.