Comparison of Frenkel and Excimer Exciton Diffusion in Perylene Bisimide Nanoparticles

Chris Rehhagen, Shahnawaz Rafiq, Kyra N. Schwarz, Gregory D. Scholes, Stefan Lochbrunner

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Exciton migration is an important process for light harvesting with organic systems and often the bottleneck. Especially the formation of trap states hinders the mobility considerably. Although excimer excitons are often referred to as traps, their mobility has been demonstrated while their nature is still unclear. Here, we compare the mobility of singlet and excimer excitons in nanoparticles consisting of the same type of perylene bisimide molecules. By changing the preparation conditions, nanoparticles with different intermolecular coupling strengths are prepared. Femtosecond transient absorption spectroscopy reveals the formation of excimer excitons from Frenkel excitons. The mobility of both exciton types is determined by evaluating exciton-exciton annihilation processes. In the lower coupling regime, singlet mobility is observed, whereas for stronger coupling the dynamics is dominated by a 10-fold increased excimer mobility. The excimer mobility can thus even be higher than the singlet mobility and is affected by the intermolecular electronic coupling.

Original languageEnglish (US)
Pages (from-to)4490-4496
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume14
Issue number19
DOIs
StatePublished - May 18 2023

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Physical and Theoretical Chemistry

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