| مستخلص: |
Investigating to the quantum regime of excitation energy transfer (EET) is one of the promising ways to reveal the photosynthetic efficiency close to one unit. However, the majority of studies have concluded that different pigment molecules contribute equally, rather than differently to EET. In this work, we explore the roles of different site energies in EET via evaluating the correlated fluctuations of site energies in two adjacent pigment molecules, and attempt to demonstrate different site roles in EET with the j-V characteristics and power through a photosynthetic quantum heat engine (QHE) model. The results show that the ascending and then descending EET is provided by fluctuations at Site 1, the pigment molecule absorbing solar photons. While the reducing EET process is achieved with the increments of correlated fluctuations at Site 2, the pigment molecule acting as the charge-transfer excited state. In addition to these, the different gap differences of the output terminal play a positive role in EET when investigating the correlated fluctuations at Site 2, but a sharply decreasing EET process is also achieved with a less correlated fluctuations at Site 2 compared with those at Site 1. The results demonstrate the unequal contributions of different pigment molecules to EET. The significance of this work is not only to clarify the roles of different pigment molecules in EET, but also deepen the understanding of the fundamental physics in EET where the EET transports through the molecular chain in photosynthetic light-harvesting complexes. In addition to this, the results also are appropriate for the EET in organic semiconductor, photovoltaic devices and quantum networks, when these systems couple to photons environment by vibrational motion of sites in the molecular chain |
