45: Reorganization energy calculations of poly(phenylene sulfide), a case study in organic semiconductor charge mobility prediction

Abstract: Aerospace composites of carbon fibers embedded in poly(phenylene sulfide) can be welded together with induction coils. However, the prevailing model of Joule heating from the fibers does not explain polymer melting at the weld interface. Kinetic Monte Carlo simulations of semiconducting polymers give insight to the path of charge carriers as a function of molecular configuration. This path in various configurations reveals whether eddy currents of charges in the neat polymer could explain this anomalous heating. Here we perform the first density functional theory calculations of reorganization energies of poly(phenylene sulfide) to enable eddy currents to be investigated via kinetic Monte Carlo simulations. We evaluate functionals (b3lyp, pbe, wb97xd, b3lyp-d3(bj)), basis sets (6-31G, 6-31G*, def2-TZVP), and show that while there is a factor of 2 variance across functionals, all combinations report reorganization energies consistent with poly(3-hexylthiophene). We aim to generalize this case study workflow to arbitrary thermoplastic chemistries. By using and contributing to software infrastructure such as the Multiscale Polymer Toolkit, flowerMD, and morphCT, we make this complex simulation workflow transparent, reproducible, usable, and extensible for the prediction of electronic properties of semiconducting polymers.