Insight on charge-transfer regimes in electron-phonon coupled molecular systems via numerically exact simulations

Abstract

Abstract Various simulation approaches exist to describe charge transport in organic solids, offering significantly different descriptions of the physics of electron-phonon coupling. This variety introduces method-dependent biases, which inevitably result in difficulties to interpret charge transport processes in a unified picture. Here, we combine numerical and analytical quantum approaches to investigate the charge-transfer dynamics in an unbiased framework. We unveil the fading of transient localisation and the formation of polarons in a broad range of vibrational frequencies and temperatures. By studying the joint electron-phonon dynamics from femtoseconds to nanoseconds, we identify three distinct charge-transport regimes: transient localisation, Soft Gating, and polaron transport. The dynamic transitions between such regimes are ruled by a buildup of the correlations between electronic motion and nuclei, which lead to the crossover between transient localisation and polaron transport. This transition is seamless at all temperatures and adiabaticities, even in the limit of low-frequency vibrational modes.