Solution-based assembly of conjugated polymers into nanowires for organic electronics


Daniel E. Acevedo Cartagena


Daniel E. Acevedo Cartagena, Jiaxin Zhu, Aditi Naik, David L. Gonzalez Arellano, Alejandro L. Briseno, James Watkins, Stephen Nonnenmann, Ryan C. Hayward

Author Affiliation: 

University of Massachusetts Amherst


Solution-based crystallization of conjugated polymers offers a scalable and attractive route to develop hierarchical structures for electronic devices. The introduction of well-defined nucleation sites into metastable solutions provides a way to regulate the crystallization behavior, and therefore the morphology of the material. I established a method focused on metastable solutions of poly(3-hexylthiophene) (P3HT). These metastable solutions allow P3HT to selectively crystallize into nanowires (NWs) on graphene-coated surfaces. It was found that the crystallization kinetics are faster with increasing P3HT molecular weight and concentration. Through in situ atomic force microscopy, I confirmed that nanowires grow vertically in a face-on orientation (i.e. the pi orbitals parallel to the substrate normal) from highly oriented pyrolytic graphite and graphene. However, as confirmed by X-ray scattering and scanning electron microscopy the face-on oriented crystals transitions from a face-on to an edge-on orientation (i.e. the _ orbitals perpendicular to the substrate normal) as the film grew thicker. Moreover, the transistors prepared by selectively crystallizing P3HT on graphene electrodes showed a film mobility two orders of magnitude higher than their spin-casted equivalents.