Time-convolutionless master equation dynamics for charge-transfer processes between semiconducting polymers

TL;DR

This paper introduces a convolutionless quantum master equation approach for mesoscopic systems, capturing non-exponential relaxation and recurrence phenomena, with applications to charge transfer in semiconducting polymers.

Contribution

The development of a general convolutionless master equation method applicable beyond the golden rule regime, demonstrated on charge transfer in organic semiconductors.

Findings

Recurrent phenomena observed in relaxation dynamics.

Both slow and fast phonon modes influence exciton decay.

Method applicable to a wide range of physical systems.

Abstract

We present here a brief overview of our work in developing a convolutionless quantum master equation approach suitable for mesoscopic sized systems. Our final equation can be used in the regimes where the golden rule approach is not applicable. Here we apply the approach to study the electronic relaxation in several models with the finite number of normal modes. For such mesoscopic systems the relaxation behavior differs substantially from the simple exponential relaxation. In particular, the equation shows the appearance of the recurrence phenomena on a time-scale determined by the slowest mode of the system. The formal results are quite general and can be used for a wide range of physical systems. Numerical results are presented for a two level system coupled to an Ohmic and super-Ohmic baths, as well as for a model of charge-transfer dynamics between semiconducting organic polymers. In this later system, we show how both slow and fast phonon modes contribute to the decay of an exciton across a heterojunction interface.