Excitons: Energetics and spatio-temporal dynamics

TL;DR

This paper reviews recent advances in understanding excitons in complex systems, highlighting the limitations of traditional models and emphasizing the roles of vibronic coupling, charge transfer, and electronic correlation in excitonic behavior.

Contribution

It provides a comprehensive overview of new experimental and theoretical approaches addressing complex excitonic phenomena beyond classical models.

Findings

Traditional Wannier and Frenkel models are insufficient for complex systems.

Vibronic coupling and charge transfer significantly influence excitonic properties.

Advanced methods reveal detailed excitonic dynamics in nano-structured and molecular systems.

Abstract

The concept of an exciton as a quasiparticle that represents collective excited states was originally adapted from solid-state physics and has been successfully applied to molecular aggregates by relying on the well-established limits of the Wannier exciton and the Frenkel exciton. However, the study of excitons in more complex chemical systems and solid materials over the past two decades has made it clear that simple concepts based on Wannier or Frenkel excitons are not sufficient to describe detailed excitonic behavior, especially in nano-structured solid materials, multichromophoric macromolecules, and complex molecular aggregates. In addition, important effects such as vibronic coupling, the influence of charge-transfer (CT) components, spin-state interconversion, and electronic correlation, which had long been studied but not fully understood, have turned out to play a central role in many systems. This has motivated new experimental approaches and theoretical studies of increasing sophistication. This article provides an overview of works addressing these issues that were published for A Special Topic of the Journal of Chemical Physics on "Excitons: Energetics and spatio-temporal dynamics" and discusses their implications.