Improved interaction between semiconducting polymer and carbon nanotubes in thermoelectric composites through covalent grafting

We developed an unconventional route to produce uniform and intimately interfaced nanocomposite films for their potential application in thermoelectric (TE) devices. Here, amino-terminated poly(3-hexylthiophene-2,5-diyl) (P3HT) was chemically adhered onto the surface of a functionalized double-walled carbon nanotube (DWCNT), via an amidation reaction, to form P3HT-grafted DWCNT (P3HT-g-DWCNT). As the P3HT chains are intimately and permanently tethered on the DWCNT surface, a well-defined P3HT/DWCNT interface prevents the DWCNT from aggregating by promoting the solubility of P3HT-g-DWCNT nanocomposites in organic solvent. Such characteristic changes in DWCNT by polymer grafting can improve the thermoelectric properties of DWCNT films. The covalently grafted P3HT-g-DWCNT film exhibits a significantly enhanced Seebeck coefficient of 116. 6 μV K−1, as compared to a physically mixed P3HT/DWCNT composite (69.2 μV K−1), in conjunction with a high power output in TE modules. This facile approach would open a new way to synthesize intimately connected nanocomposites made up of conductive polymers and carbon materials for high performance thermoelectrics.

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