Chain Conformations and Photoluminescence in Poly(di-n-octylfluorene)

TL;DR

This paper investigates the molecular conformations and photoluminescent properties of poly(di-n-octylfluorene), revealing distinct conformational isomers and providing a detailed theoretical analysis that matches experimental spectra.

Contribution

It combines molecular modeling and spectroscopic analysis to identify conformational isomers and accurately reproduce photoluminescence spectra of the polymer.

Findings

Identification of three conformational isomers with different torsion angles

Confirmation of the beta phase as a distinct conformational class

Accurate reproduction of absorption and emission spectra through theoretical modeling

Abstract

The diverse steady-state spectroscopic properties of poly(di-n-octylfluorene) are addressed from a molecular-level perspective. Modeling of representative oligomers support the experimental observation of at least three distinguishable classes of conformational isomers with differing chain torsion angles. One class appears to be populated by a single compact structural isomer and this conforms to the so called beta phase. A rigorous Franck-Condon analysis of the photoluminescence in conjunction with Frenkel-type exciton band structure calculations are performed. These results accurately reproduce all major spectral features of the photoabsorption and those of singlet exciton emission.