Artificial photosynthetic reaction centers coupled to light-harvesting antennas

TL;DR

This paper presents a theoretical analysis of artificial photosynthetic systems with different antenna arrangements, demonstrating that cascade energy transfer can outperform direct coupling in photon absorption and energy conversion efficiency.

Contribution

It introduces a comparative model of two antenna arrangements, showing cascade transfer enhances broad-spectrum absorption and efficiency over direct coupling.

Findings

Cascade energy transfer absorbs a broader wavelength range.

Cascade configuration achieves higher energy conversion efficiency.

Direct coupling arrangement is less effective in broad-spectrum absorption.

Abstract

We analyze a theoretical model for energy and electron transfer in an artificial photosynthetic system. The photosystem consists of a molecular triad (i.e., with a donor, a photosensitive unit, and an acceptor) coupled to four accessory light-harvesting antennas pigments. The excitation energy transfer from the antennas to the artificial reaction center (the molecular triad) is here described by the F\"{o}rster mechanism. We consider two different kinds of arrangements of the accessory light-harvesting pigments around the reaction center. The first arrangement allows direct excitation transfer to the reaction center from all the surrounding pigments. The second configuration transmits energy via a cascade mechanism along a chain of light-harvesting chromophores, where only one chromophore is connected to the reaction center. At first sight, it would appear that the star-shaped configuration, with all the antennas directly coupled to the photosensitive center, would be more efficient. However, we show that the artificial photosynthetic system using the cascade energy transfer absorbs photons in a broader wavelength range and converts their energy into electricity with a higher efficiency than the system based on direct couplings between all the antenna chromophores and the reaction center.