Charge carrier dynamics in phonon-induced fluctuation systems from time-dependent wavepacket diffusion approach

Abstract

A time-dependent wavepacket diffusion method is proposed to deal with charge transport in organic crystals. The electron-phonon interactions in both site energies and electronic couplings are incorporated by the time-dependent fluctuations which are generated from the corresponding spectral density functions. The numerical demonstrations reveal that the present approach predicts the consistent charge carrier dynamics with the rigorous quantum approaches. In addition, the diffusion coefficients obtained from the Marcus formula are well reproduced at the weak electronic coupling and high temperature limits. It is also found that the charge mobility feature of the crossover from the band-like to the hopping-type cannot be predicted from the fluctuations induced by the linear electron-phonon interactions with an Ohmic spectral density; however, it indeed appears as the electronic coupling fluctuation exponentially depends on the nuclear coordinates. Finally, it should be noted that although the present approach neglects the imaginary fluctuation, it essentially incorporates the coherent motion of the charge carrier and quantum effect of the phonon motion with a broad regime of the fluctuations for symmetric systems. Besides, the approach can easily be applied to systems having thousands of sites, which allows one to investigate charge transport in nanoscale organic crystals.

Engineering nanometre-scale coherence in soft matter

“…However, this current computational approach largely underestimates the resistance enhancement in evenlength sequences, as discussed below. SSE analysis using classic (pure real-valued) noise violates detailed balance 21 and charge equally populates monomers with different energies in the long-time limit. SSE approaches work well for chains of identical monomer units (as demonstrated by path-integral analysis), but overestimate CT rates in systems with heterogeneous chains 21 .…”

“…We assumed that gold is able to oxidize guanine, consistent with experimental 16 and theoretical findings 17 . We used a time-dependent stochastic Schrödinger equation (SSE) model [18][19][20][21] to simulate transport through fluctuating molecular assemblies built of repeating units with mean energies that are degenerate with the Fermi energy of the electrodes (see Methods and Supplementary Section 3).…”

Effects of Charge Transfer State and Exciton Migration on Singlet Fission Dynamics in Organic Aggregates

“…(14) can correctly predict exact carrier dynamics for most of realistic organic aggregates. [53][54][55][56][57][58] F α,β (t) is the so-called stochastic force in numerical simulations as we take α and β as random variables, it is generated by the following expression…”

Juxtaposing density matrix and classical path-based wave packet dynamics

“…A comparison of Ehrenfest dynamics and exact quantum dynamics has been performed earlier 28 showing a good performance of the Ehrenfest dynamics concerning coherent dynamics. In addition to some recent reports, 29,30 a more detailed analysis is performed in the present study. To be able to perform these tests, we generate random site energies based on a Drude spectral density.…”