Size dependent exciton dynamics in one-dimensional perylene bisimide aggregates

TL;DR

This study investigates how the size of one-dimensional perylene bisimide aggregates affects exciton dynamics, revealing temperature-dependent behavior from infinite chains to small fragments through spectroscopy and simulations.

Contribution

It introduces a combined experimental and computational approach to analyze size-dependent exciton dynamics in perylene bisimide aggregates across temperatures.

Findings

At low temperatures, aggregates behave as infinite chains with diffusion-driven exciton-exciton annihilation.

Increasing temperature causes aggregates to break into small fragments.

Time-dependent anisotropy supports the temperature-induced decomposition scenario.

Abstract

The size dependent exciton dynamics of one-dimensional aggregates of substituted perylene bisimides are studied by ultrafast transient absorption spectroscopy and kinetic Monte-Carlo simulations in dependence on the temperature and the excitation density. For low temperatures the aggregates can be treated as infinite chains and the dynamics is dominated by diffusion driven exciton-exciton annihilation. With increasing temperature the aggregates decompose into small fragments consisting of very few monomers. This scenario is also supported by the time dependent anisotropy deduced from polarization dependent experiments.