PFO-BPy Solubilizers for SWNTs: Modelling of Polymers from Oligomers

TL;DR

This study uses TDDFT to identify the smallest oligomer model that accurately represents the electronic and optical properties of PFO-BPy polymers, aiding in the modeling of polymer-SWNT hybrid systems for photovoltaic applications.

Contribution

It demonstrates that the Py-PFO-Py monomer with shortened side chains can effectively model the PFO-BPy polymer, simplifying computational studies.

Findings

Py-PFO-Py monomer accurately models the polymer

Shortened side chains do not significantly affect properties

Modeling with monomers reduces computational complexity

Abstract

Due to their exeptional physical properties, single walled carbon nanotubes (SWNTs) embedded in organic polymers (polymer-SWNT hybrid systems) are promising materials for organic photovoltaic (OPV) devices. Already at the SWNT sorting and debundling step, polymers such as the copolymer of 9,9-dioctylfluorenyl-2,7-diyl and bipyridine (PFO-BPy) are used as solubilizers. However, to model polymer-SWNT hybrid systems, we must first determine the smallest oligomer needed to sufficiently describe the electronic and optical absorption properties of the polymer. To do so, we use time dependent density functional theory (TDDFT) to model the PFO-BPy polymer using the monomers, dimers and trimers of the PFO-BPy and Py-PFO-Py building blocks, which are also compared to the infinitely long polymer. We find the Py-PFO-Py monomer, with shortened side chains, already describes the PFO-BPy polymer within the expected accuracies of TDDFT.