A twisted polydiacetylene quantum wire: Influence of conformation on excitons in polymeric quasi-1D systems

TL;DR

This study investigates highly luminescent, twisted polydiacetylene chains in a new crystal structure, revealing their behavior as quasi-1D quantum wires and establishing a relationship between twist angle and exciton energy.

Contribution

It demonstrates that non-planar, twisted PDA chains can still act as quantum wires, expanding understanding of structure-property relationships in conjugated polymers.

Findings

Twisted PDA chains behave as quasi-1D quantum wires.

Exciton energy E0 increases with twist angle.

Exciton binding energy and Bohr radius are significantly affected.

Abstract

Highly luminescent isolated polydiacetylene (PDA) chains in a new diacetylene crystal are studied. The diacetylene crystal structure and theoretical calculations suggest that the chains are not planar and more strongly twisted than any known PDA. Yet the chains behave as quasi perfect quantum wires, showing that this behaviour is generic among PDA, provided crystal order is high enough. The exciton energy, E0, is higher than in any other well ordered PDA providing a relationship between E0 and twist angle. On the other hand the exciton binding energy and Bohr radius are significantly affected as demonstrated in electroabsorption experiments (and developed in a companion paper).