Controlling Poly(3-hexythiophene) Hierarchical Polymer/SWCNT Nanohybrid Shish-Kebab Morphologies in Marginal Solvents

Abstract

In organic optoelectronic devices, the self-assembly behavior of the conjugated polymer poly(3-hexylthiophene) (P3HT) into structured aggregates significantly influences the device’s performance, with processing conditions playing a key role. Incorporating carbon nanotubes (CNTs) into a P3HT solution can form hierarchical supramolecular structures known as nanohybrid shish-kebabs (NHSKs). These structures alter the morphology of polymer aggregates and provide an alternative pathway for improved charge transport in thin film devices. Herein, we investigated the impact of solvent quality using different combinations of chloroform and anisole during the quasi-isothermal crystallization of P3HT:CNTs. We found that NHSKs of different nanowire lengths can be formed through changing solvent quality while maintaining a constant P3HT:SWCNT ratio and a constant SWCNT concentration. Optical absorbance measurements showed that increasing the amount of the good solvent (chloroform) to 10.19% (v/v) reduced the exciton bandwidth by 36.4% compared to the NHSK solution that only contained ~2.37% (v/v). This observation demonstrates the importance of solvent quality and how this processing parameter directly leads to the enhanced crystallization of supramolecular structures.