Enhancing Predictive Simulations of Conjugated Polymers through Exciton-Coupled Dynamics

Abstract Among the semiconducting conjugated polymers (CPs), cis-polyacetylene (cis-PA) has recently received attention due to its advances in organic electronics applications. Excitonic effects and energy dissipation affect the critical properties of these materials. Here, cis-PA oligomers are studied in two different forms: (a) pristine cis-PA (undoped) and (b) cis-PA codoped with sodium and phosphorus fluoride. We introduce the Bethe–Salpeter equation (BSE) + Redfield framework for converting nonradiative energy dissipation channels from an independent orbital approximation (IOA) framework to an excitonic basis. The excitonic nonradiative and radiative channels are used to calculate rates for photoluminescence quantum yield (PLQY). Excitonic effects produce system-dependent changes in phonon-mediated relaxation. They accelerate relaxation and reduce the PLQY in undoped cis-PA, while slowing relaxation and increasing the PLQY relative to the IOA description in codoped cis-PA. These findings emphasize the influence of state degeneracy and electron–hole (e–h) interactions, which are inherently captured within the exciton framework.