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Lookup NU author(s): Dr Thomas PopeORCiD, Dr Julien EngORCiD, Professor Thomas Penfold
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
We present a detailed investigation into the excited state properties of a planar D3h symmetric azatriangulenetrione, HTANGO, which has received significant interest due to its high solid-state phosphorescence quantum yield and therefore potential as an organic room temperature phosphorescent (ORTP) dye. Using a model linear vibronic coupling Hamiltonian in combination with quantum dynamics simulations, we observe that intersystem crossing (ISC) in HTANGO occurs with a rate of ā¼1010 sā1, comparable to benzophenone, an archetypal molecule for fast ISC in heavy metal free molecules. Our simulations demonstrate that the mechanism for fast ISC is associated with the high density of excited triplet states which lie in close proximity to the lowest singlet states, offering multiple channels into the triplet manifold facilitating rapid population transfer. Finally, to rationalize the solid-state emission properties, we use quantum chemistry to investigate the excited state surfaces of the HTANGO dimer, highlighting the influence and importance of the rotational alignment between the two HTANGO molecules in the solid state and how this contributes to high phosphorescence quantum yield.
Author(s): Pope T, Eng J, Monkman A, Penfold TJ
Publication type: Article
Publication status: Published
Journal: Journal of Chemical Theory and Computation
Year: 2024
Volume: 20
Issue: 3
Pages: 1337ā1346
Online publication date: 25/01/2024
Acceptance date: 04/01/2024
Date deposited: 26/01/2024
ISSN (print): 1549-9618
ISSN (electronic): 1549-9626
Publisher: American Chemical Society
URL: https://doi.org/10.1021/acs.jctc.3c01220
DOI: 10.1021/acs.jctc.3c01220
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