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This is a In Vitro Study study.

August 21, 2025

Tuning Exciton Diffusion in Organic Semiconductors through Hybridization with Charge-Transfer Excitations.

JCJesús CerdáUniversity of Mons SGSamuele GianniniUniversity of Pisa LXLai XuInstitute of Molecular Functional Materials

Key Points

Exciton diffusion can improve significantly, with coefficients increasing by up to an order of magnitude when optimized.
Exciton transport is influenced by the energy offset and coupling patterns between Frenkel and charge-transfer states.
Large-scale nonadiabatic surface hopping dynamics were used to simulate interactions in realistic organic materials.
Hybridization effects reveal key design principles for enhancing exciton mobility that could influence future organic semiconductor development.

Abstract

The interplay between Frenkel (FE) excitons and charge-transfer (CT) states crucially impacts exciton transport in organic molecular aggregates. Using large-scale nonadiabatic surface hopping dynamics on Holstein-type Hamiltonians parametrized for realistic systems, we here show that exciton diffusion strongly depends on the FE-CT energy offset (ΔE) and the sign pattern of excitonic and electronic couplings. Hybridization at the bottom of the exciton band (H- and J+) promotes delocalized states with moderate CT character (30-50%), boosting diffusion coefficients by up to an order of magnitude. In contrast, hybridization at the top of the band (H+ and J-) leads to stronger localization and reduced transport. These trends persist even under strong vibronic coupling, where band-based descriptions fail, highlighting robust design principles for enhancing exciton mobility in organic materials.

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