Photo-excitation of a light-harvesting supra-molecular triad: a Time-Dependent DFT study

TL;DR

This study uses time-dependent density-functional theory to analyze the excited state properties and photo-excitation mechanisms of a complex light-harvesting triad, providing insights consistent with experimental data.

Contribution

First TDDFT calculation on a large light-harvesting triad revealing accurate excited state properties and photo-excitation mechanisms.

Findings

Photo-absorption spectrum matches experimental data

Provides insight into charge transfer mechanisms

Demonstrates TDDFT's effectiveness for large systems

Abstract

We present the first time-dependent density-functional theory (TDDFT) calculation on a light harvesting triad carotenoid-diaryl-porphyrin-C60. Besides the numerical challenge that the ab initio study of the electronic structure of such a large system presents, we show that TDDFT is able to provide an accurate description of the excited state properties of the system. In particular we calculate the photo-absorption spectrum of the supra-molecular assembly, and we provide an interpretation of the photo-excitation mechanism in terms of the properties of the component moieties. The spectrum is in good agreement with experimental data, and provides useful insight on the photo-induced charge transfer mechanism which characterizes the system.