Low-temperature quenching of one-dimensional localised Frenkel excitons

TL;DR

This paper provides a theoretical model for low-temperature exciton quenching in one-dimensional disordered systems, highlighting the role of intra-segment scattering and comparing with experimental data.

Contribution

It introduces a rate equation approach to analyze exciton diffusion and quenching, emphasizing the importance of intra-segment scattering in localized Frenkel excitons.

Findings

Activation temperature is comparable to the absorption band width.

Intra-segment scattering significantly influences exciton diffusion.

The model aligns with experimental observations of exciton-exciton annihilation.

Abstract

We present a theoretical analysis of low-temperature quenching of one-dimensional Frenkel excitons that are localised by moderate on-site (diagonal) uncorrelated disorder. Exciton diffusion is considered as an incoherent hopping over localization segments and is probed by the exciton fluorescence quenching at point traps. The rate equation is used to calculate the temperature dependence of the exciton quenching. The activation temperature of the diffusion is found to be of the order of the width of the exciton absorption band. We demonstrate that the intra-segment scattering is extremely important for the exciton diffusion. We discuss also experimental data on the fast exciton-exciton annihilation in linear molecular aggregates at low temperatures.