Phonon-driven ultrafast exciton dissociation at donor-acceptor polymer heterojunctions

TL;DR

This study presents a quantum-dynamical analysis of phonon-driven exciton dissociation at polymer heterojunctions, revealing two decay pathways influenced by vibrational modes, aligning with spectroscopic observations.

Contribution

It introduces a hierarchical electron-phonon model for analyzing exciton dissociation, identifying two key decay pathways and their dependence on vibrational mode interplay.

Findings

Identified direct and indirect exciton dissociation pathways.

Demonstrated the critical role of vibrational mode interplay.

Results align with time-resolved spectroscopic data.

Abstract

A quantum-dynamical analysis of phonon-driven exciton dissociation at polymer heterojunctions is presented, using a hierarchical electron-phonon model parameterized for three electronic states and 24 vibrational modes. Two interfering decay pathways are identified: a direct charge separation, and an indirect pathway via an intermediate bridge state. Both pathways depend critically on the dynamical interplay of high-frequency C=C stretch modes and low-frequency ring-torsional modes. The ultrafast, highly non-equilibrium dynamics is consistent with time-resolved spectroscopic observations.