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π-Helical push–pull dyes were prepared and their (chir)optical properties were investigated both experimentally and computationally. Specific fluorescent behaviour of bis-substituted system was observed with unprecedented solvent effect on the intensity of circularly polarized luminescence (CPL, dissymmetry factor decreasing from 10 −2 to 10 −3 with an increase in solvent polarity) that was linked to a change in symmetry of chiral excited state and suppression of interbranched exciton coupling. The results highlight the potential of CPL spectroscopy to study and provide a deeper understanding of electronic photophysical processes in chiral π-conjugated molecules.
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Exciton Bimolecular Annihilation Dynamics in Push–Pull Semiconductor Polymers
Exciton−exciton annihilation is a ubiquitous nonlinear dynamic phenomenon in materials hosting Frenkel excitons. In this work, we investigate the nonlinear exciton dynamics of an electron push−pull conjugated polymer by fluence-dependent transient absorption and excitation-correlation photoluminescence spectroscopy, where we can quantitatively show the latter to be a more selective probe of the nonlinear dynamics. Simulations based on a time-independent exciton annihilation model show a decreasing trend for the extracted annihilation rates with excitation0 fluence. Further investigation of the fluence-dependent transients suggests that the exciton−exciton annihilation bimolecular rates are not constant in time, displaying a t−1/2 time dependence, which we rationalize as reflective of one-dimensional exciton diffusion, with a length estimated to be 9 ± 2 nm. In addition, exciton annihilation gives rise to a long-lived species that recombines on a nanosecond time scale. Our conclusions shed broad light onto nonlinear exciton dynamics in push−pull conjugated polymers.
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- Award ID(s):
- 1922111
- PAR ID:
- 10531360
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry Letters
- Edition / Version:
- 1
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 1948-7185
- Page Range / eLocation ID:
- 272 to 280
- Subject(s) / Keyword(s):
- exciton-exciton annihilation push-pull polymers DPP-DTT photophysical spectroscopy
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1021/acs.jpclett.3c03094
