Artificial Photosynthesis: Is Computation Ready for the Challenge Ahead?

Abstract

A tremendous effort is currently devoted to the generation of novel hybrid materials with enhanced electronic properties for the creation of artificial photosynthetic systems. This compelling and challenging problem is well-defined from an experimental point of view, as the design of such materials relies on combining organic materials or metals with biological systems like light harvesting and redox-active proteins. Such hybrid systems can be used, e.g., as bio-sensors, bio-fuel cells, biohybrid photoelectrochemical cells, and nanostructured photoelectronic devices. Despite these efforts, the main bottleneck is the formation of efficient interfaces between the biological and the organic/metal counterparts for efficient electron transfer (ET). It is within this aspect that computation can make the difference and improve the current understanding of the mechanisms underneath the interface formation and the charge transfer efficiency. Yet, the systems considered (i.e., light harvesting protein, self-assembly monolayer and surface assembly) are more and more complex, reaching (and often passing) the limit of current computation power. In this review, recent developments in computational methods for studying complex interfaces for artificial photosynthesis will be provided and selected cases discussed, to assess the inherent ability of computation to leave a mark in this field of research.

Thermal site energy fluctuations in photosystem I: new insights from MD/QM/MM calculations

“…An in-depth understanding of this remarkably high efficiency may guide future designs of articial light harvesting (LH) systems. [2][3][4] The cyanobacterial (T. elongatus) PSI is a trimeric transmembrane protein supercomplex. [5][6][7] Each monomer comprises twelve protein subunits, 96 chlorophylls, 22 carotenoids, four lipids, three iron-sulfur clusters and two phylloquinones.…”

“…PSI also presents signicant challenges to computational methods, especially regarding the chlorophylls governing the energy and charge transfer. 4,18,33 The protein environment in pigment-protein complexes such as PSI is specic for each chlorophyll, which leads to individual absorption spectra or site energies for each chromophore. 32,34 In accordance with the Gouterman-model, 35 these site energies correspond to the Q y state as the lowest excited state of chlorophyll.…”

The extended star graph as a light-harvesting-complex prototype: excitonic absorption speedup by peripheral energy defect tuning

“…As a consequence, photosynthesis has recently attracted a large amount of research interest. More precisely, a special attention has been paid to elaborate artificial LHCs that could be able to mimic natural photosynthesis to efficiently convert the energy of light into chemical fuel [6][7][8][9].…”

Role of Dark Excitons in the Excitation Energy Transfer of Carbon Nanotubes

“…We think that the information got from 3T can be applicable to sexithiophene. For SWNTs, we choose a zigzag one, (7,0), and a helical one, (6,2), to inspect the influence of helicity on EET. In section 3.1, we will first discuss electronic couplings in the SQ dimer and in the 3T dimer, emphasizing the dominant role of high multipole interactions when the separation between donor and acceptor is around 3.4 Å, which is the typical separation between molecules and SWNTs.…”

“…Electronic excitation energy can be transferred from donor to acceptor through the coupling of excitons in these two systems. Excitation energy transfer (EET) is an important process in many natural and artificial systems, e.g., EET from carotenoids to chlorophylls in the photosynthetic systems of plants and EET among the donor molecules in organic photovoltaic cells. − The mechanism for EET between molecular systems is well-studied and well-understood. EET between the singlet excitons of molecules which are separated by a long distance can be described well by the Förster theory .…”