  In this paper, we apply the polaron master equation, which offers the
possibilities to interpolate between weak and strong system-bath coupling, to
study how system-bath couplings affect charge transfer processes in Photosystem
II reaction center (PSII RC) inspired quantum heat engine (QHE) model in a wide
parameter range. The effects of bath correlation and temperature, together with
the combined effects of these factors are also discussed in details. The
results show a variety of dynamical behaviours. We interpret these results in
terms of noise-assisted transport effect and dynamical localization which
correspond to two mechanisms underpinning the transfer process in
photosynthetic complexes: One is resonance energy transfer and the other is
dynamical localization effect captured by the polaron master equation. The
effects of system-bath coupling and bath correlation are incorporated in the
effective system-bath coupling strength determining whether noise-assisted
transport effect or dynamical localization dominates the dynamics and
temperature modulates the balance of the two mechanisms. Furthermore, these two
mechanisms can be attributed to one physical origin: bath-induced fluctuations.
The two mechanisms is manifestations of dual role played by bath-induced
fluctuations within respective parameter range. In addition, we find that the
effec- tive voltage of QHE exhibits superior robustness with respect to the
bath noise as long as the system-coupling strength is not too large.
