Formally Exact Simulations of Mesoscale Exciton Diffusion in a Photosynthetic Aggregate

TL;DR

This paper uses a highly accurate simulation method to study exciton diffusion in artificial light-harvesting complexes, revealing large diffusion lengths influenced by packing density, which advances understanding of energy transfer in biohybrid materials.

Contribution

It introduces the use of the adaptive Hierarchy of Pure States (adHOPS) for exact simulation of exciton dynamics in artificial aggregates, demonstrating its effectiveness and revealing new insights into exciton diffusion lengths.

Findings

Exciton diffusion length ranges from 100 nm to 300 nm depending on packing density.

adHOPS enables formally exact simulations of excited-state processes in complex molecular systems.

Artificial aggregates can support significantly longer exciton diffusion than biological counterparts.

Abstract

The photosynthetic apparatus of plants and bacteria combine atomically precise pigment-protein complexes with dynamic membrane architectures to control energy transfer on the 10-100 nm length scales. Recently, synthetic materials have integrated photosynthetic antennae proteins to enhance exciton transport, though the influence of artificial packing on the excited-state dynamics in these biohybrid materials remains unclear. Here, we use the adaptive Hierarchy of Pure States (adHOPS) to perform a formally exact simulation of excitation energy transfer within artificial aggregates of light harvesting complex 2 (LH2) with a range of packing densities. We find that LH2 aggregates support a remarkable exciton diffusion length ranging from 100 nm at a biological packing density to 300 nm at the densest packing previously suggested in an artificial aggregate. The unprecedented scale of these calculations also underscores the efficiency with which adHOPS simulates excited-state processes in realistic molecular materials.