Covalent interactions between carbon nanotubes and P3HT by thiol-ene click chemistry towards improved thermoelectric performance

A new covalent functionalization method is developed to produce a uniform multiwalled carbon nanotube/poly(3-hexylthiophene) (MWCNT-P3HT) nanocomposite via a thiol-ene click reaction between vinyl-terminated P3HT and thiol-functionalized MWCNTs. Microscopic and spectroscopic measurements confirm the covalent grafting of P3HT onto the surface of the MWCNTs. The covalently P3HT-functionalized MWCNTs show good dispersibility in hydrophobic solution. The intimate and permanent connection between the two components in the MWCNT-P3HT nanocomposite allowed the enhancement of charge transfer from P3HT to the MWCNTs. Relying on this unique feature, MWCNT-P3HT nanocomposite films for use in thermoelectric devices were fabricated, and the power generation characteristics were measured. Significantly, such MWCNT-P3HT nanocomposites showed more than twice the improved thermoelectric performance, as compared to directly mixed MWCNT/P3HT blends. This covalent grafting approach achieved via thiol-ene click chemistry offers a robust strategy for the synthesis of a variety of CNT-conductive polymer nanocomposites with an intimate contact interface for their potential application in energy conversion devices.