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Red-shifted delayed fluorescence at the expense of photoluminescence quantum efficiency ‒ an intramolecular charge-transfer molecule based on a benzodithiophene-4,8-dione acceptor

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posted on 20.05.2019, 13:59 by Stephanie Montanaro, Alexander J. Gillett, Sascha Feldmann, Emrys W. Evans, Felix PlasserFelix Plasser, Richard H. Friend, Iain WrightIain Wright
Employing the thiophene based quinone, benzo[1,2-b:4,5-b′]dithiophene-4,8-dione, as the electron-accepting moiety alongside N-phenylcarbazole donors to produce a donor–π–acceptor–π–donor (D–π–A–π–D) molecule has yielded a new red emitter displaying delayed fluorescence. This new molecule shows strongly (over 100 nm) red-shifted emission when compared to an anthraquinone based analogue. Cyclic voltammetry complemented by computational insights prove that this red-shift is due to the significantly stronger electron-accepting ability of the thiophene quinone compared to anthraquinone. Photophysical and computational studies of this molecule have revealed that while the presence of the thiophene containing acceptor facilitates rapid intersystem crossing which is comparable to anthraquinone analogues, the reverse intersystem crossing rate is slow and non-radiative decay is rapid which we can attribute to low-lying locally excited states. This limits the total photoluminescence quantum efficiency to less than 10% in both solution and the solid state. These results provide a useful example of how very minor structural variations can have a defining impact on the photophysical properties of new molecular materials.

Funding

I. A. W. thanks Loughborough University for support and the Royal Society of Chemistry Research Fund (RF18-5353) for funding. I. A. W. also thanks the Durham University Mass Spectrometry Service for ASAP-MS. S. M. acknowledges Loughborough University for providing a PhD studentship. A. J. G and R. H. F. thank the EPSRC for support. S. F. acknowledges funding from the Studienstiftung des deutschen Volkes and the EPSRC.

History

School

  • Science

Department

  • Chemistry

Published in

Physical Chemistry Chemical Physics

Volume

21

Issue

20

Pages

10580-10586

Citation

MONTANARO, S. ... et al, 2019. Red-shifted delayed fluorescence at the expense of photoluminescence quantum efficiency ‒ an intramolecular charge-transfer molecule based on a benzodithiophene-4,8-dione acceptor. Physical Chemistry Chemical Physics, 21 (20), pp.10580-10586.

Publisher

Royal Society of Chemistry (RSC) © the Owner Societies

Version

AM (Accepted Manuscript)

Publisher statement

This paper was accepted for publication in the journal Physical Chemistry Chemical Physics and the definitive published version is available at https://doi.org/10.1039/c9cp02186h.

Acceptance date

03/05/2019

Publication date

2019-05-06

ISSN

1463-9076

eISSN

1463-9084

Language

en

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