On the trade-off between processability and opto-electronic properties of single wall carbon nanotube derivatives in thin film heterojunctions

A flow functionalization route has been employed to derivatize single wall carbon nanotubes (SWCNTs) by thienylphenyl groups. The SWCNT derivatives in the most soluble fraction have been characterized by thermogravimetric analysis, DLS analysis, DFT calculations, and UV-vis-NIR, microRaman and IR spectroscopies to study the degree of functionalization, the concentration of SWCNTs in solution, the dimension of the aggregates in solutions, the density of defects, and the presence of the thienylphenyl groups. Thin-film heterojunctions made of SWCNT derivatives and poly(3-hexylthiophene) (P3HT) have been prepared by various methods employing the Langmuir-Schaefer technique, spin-coating and thermal annealing processes. By comparing the batch and the flow functionalizations, a trade-off between solubility, processability and the thin-film opto-electronic properties has been found as a result of the degree of functionalization.