Impact of Fluorine Substituents on π‐Conjugated Polymer Main‐Chain Conformations, Packing, and Electronic Couplings

Abstract

Taking the π-conjugated polymers PBDT[2X]T (X = H, F) as model systems, the effects of fluorine substitution on main-chain conformations, packing, and electronic couplings are examined. This combination of molecular dynamics simulations and solid-state NMR shows that a higher propensity for backbone planarity in PBDT[2F]T leads to more pronounced, yet staggered, chain stacking, which generally leads to higher electronic couplings and binding energy between neighboring chains.

Donor–acceptor stacking arrangements in bulk and thin-film high-mobility conjugated polymers characterized using molecular modelling and MAS and surface-enhanced solid-state NMR spectroscopy

“…15–18 However, there remains a lack of experimental techniques that can provide structural information on the atomic level to test or verify theoretically-predicted structures. Some of the most widely used techniques have been grazing incidence wide-angle X-ray scattering (GIWAXS) 6,7,9,19–22 and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, 23–25 which can provide information on the molecular orientations and spacing of the polymer backbones.…”

On the Physical Origins of Charge Separation at Donor–Acceptor Interfaces in Organic Solar Cells: Energy Bending versus Energy Disorder

“…An example of such structural impact of non‐covalent (weak) intramolecular interaction was shown by Conboy et al . Accordingly, the important positive impact on the OSC efficiency found for several fluorinated polymers as compared to the non‐fluorinated analogs could constitute a possible example; while efforts to explain the positive impact of the fluorine atoms were principally based on the improved packing in these materials, an important part of the impact may stem from their double potential to be easily deformable at the interface and easily planarizable in the bulk.…”

Impact of Fluorine Atoms on Perylene Diimide Derivative for Fullerene‐Free Organic Photovoltaics

“…among the molecules . Such interactions can push F‐containing molecules more closely packed and facilitate effective energy transfer and charge transport in the films . Additionally, strong electron affinity of F atom is an impelling source to tune the energy levels of organic semiconductors.…”

“…[32][33][34] Such interactions can push F-containing molecules more closely packed and facilitatee ffective energy transfer and charge transport in the films. [35][36][37][38] Additionally,s trong electron affinity of Fa tom is an impelling sourcet ot une the energyl evels of organic semiconductors. Recently,f luorinated conjugated polymers exhibited high chargem obilities, and weak bimolecular recombination when incorporated into OPVs.…”