Lowering of the singlet-triplet energy gap via intramolecular exciton-exciton coupling
Journal article, 2024

Organic dyes typically have electronically excited states of both singlet and triplet multiplicity. Controlling the energy difference between these states is a key factor for making efficient organic light emitting diodes and triplet sensitizers, which fulfill essential functions in chemistry, physics, and medicine. Here, we propose a strategy to shift the singlet excited state of a known sensitizer to lower energies without shifting the energy of the triplet state, thus without compromising the ability of the sensitizer to do work. We covalently connect two to four sensitizers in such a way that their transition dipole moments are aligned in a head-to-tail fashion, but, through steric encumbrance, the delocalization is minimized between each moiety. Exciton coupling between the singlet excited states considerably lowers the first excited singlet state energy. However, the energy of the lowest triplet excited state is unperturbed because the exciton coupling strength depends on the magnitude of the transition dipole moments, which for triplets are very small. We expect that the presented strategy of designed intramolecular exciton coupling will be a useful concept in the design of both photosensitizers and emitters for organic light emitting diodes as both benefits from a small singlet-triplet energy gap.

Author

Clara Schäfer

University of Gothenburg

Rasmus Ringström

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Jörg Hanrieder

University of Gothenburg

University College London (UCL)

Martin Rahm

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Bo Albinsson

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Karl Börjesson

University of Gothenburg

Nature Communications

2041-1723 (ISSN) 20411723 (eISSN)

Vol. 15 1 8705

Subject Categories

Organic Chemistry

DOI

10.1038/s41467-024-53122-7

PubMed

39379375

More information

Latest update

10/18/2024