Ultrafast time-resolved spectroscopy elucidating photo-driven electron and energy transfer processes in a broadband light-absorbing BODIPY-C60-distyryl BODIPY triad
Institut Des Sciences Moléculaires d’Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
2 Institut Lavoisier de Versailles, Université Paris-Saclay, UVSQ, CNRS, 78000, Versailles, France
3 Fac Phys, Quantum Elec. Lab, Adam Mickiewicz Univ in Poznan, 61614, Poznan, Poland
4 Université Paris-Saclay, ENS Paris-Saclay, CNRS, PPSM, 91190, Gif-Sur-Yvette, France
5 Laboratoire de Spectroscopie Pour Les Interactions, La Réactivité Et L’Environnement, Univ. Lille, CNRS, UMR 8516, LASIRE, 59 000, Lille, France
Accepted: 20 September 2022
Published online: 17 October 2022
Photoinduced electron and energy transfer pathways are elucidated in a panchromatic light-absorbing, covalently linked triad (BODIPY-C60-distyryl BODIPY, noted as BDP-C60-DSBDP) along with the two reference dyads: BODIPY-C60 (BDP-C60) and distyryl-BODIPY-C60 (DSBDP-C60). The flexible linker between the BODIPY and C60 units leads to different possible conformations with varying donor–acceptor distances. Ultrafast transient absorption along with the time-resolved emission spectroscopies revealed the occurrence of different photoinduced electron/energy transfer processes in these conformers. Photoexcitation of the BODIPY units in the two reference dyads leads to one electron and two energy transfer steps from BODIPY to C60. However, in the BDP-C60-DSBDP triad, additional energy transfer processes from BDP to DSBDP were evidenced upon photoexcitation of the BDP unit. The singlet excited state of DSBDP in the triad then follows the same relaxation route as that of the DSBDP-C60 dyad. The intricate photophysics, particularly the formation of radical ion pairs in these flexible covalently linked donor–acceptor systems contribute to our fundamental understanding of electron and energy transfer mechanisms, which is important to build donor–acceptor assemblies for energy applications.
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