Solution-Phase Conformation and Dynamics of Conjugated Isoindigo-Based Donor–Acceptor Polymer Single Chains

Conjugated polymers
are the key material in thin-film organic optoelectronic
devices due to the versatility of these molecules combined with their
semiconducting properties. A molecular-scale understanding of conjugated
polymers is important to the optimization of the thin-film morphology.
We examine the solution-phase behavior of conjugated isoindigo-based
donor–acceptor polymer single chains of various chain lengths
using atomistic molecular dynamics simulations. Our simulations elucidate
the transition from a rod-like to a coil-like conformation from an
analysis of normal modes and persistence length. In addition, we find
another transition based on the solvent environment, contrasting the
coil-like conformation in a good solvent with a globule-like conformation
in a poor solvent. Overall, our results provide valuable insights
into the transition between conformational regimes for conjugated
polymers as a function of both the chain length and the solvent environment,
which will help to accurately parametrize higher level models.