The impact of molecular weight on nanoscale supramolecular structure of semiconducting poly(3-hexylthiophene) on carbon nanotubes and photophysical properties

The present study is in sequel to the previous research (Phys. Chem. Chem. Phys. 16 (2014) p. 19122), where a solution-based nucleation and growth approach that involved direct epitaxial nucleation of nanofibres of poly(3-hexylthiophene) (P3HT) on carbon nanotubes (CNTs) for potential use as next-generation building blocks for applications including field-effect transistors and photovoltaic devices, was described. Also presented was a theoretical analysis of epitaxial mechanism of nucleation and growth of semiconducting conjugated polymers notably, P3HT on CNTs. In the present study, we elucidate the impact of molecular weight of P3HT on structural morphology and photophysical properties. The change in average molecular weight of P3HT from ~14 to ~60 kDa resulted in several structural changes, even though the mechanism of nucleation and growth continued to be epitaxial process. In the case of high-molecular weight P3HT, the crystallized fibrils were ~200–400 nm in length and ~2–3-nm thick. In contrast, fo...