Axial and helical thermally activated delayed fluorescence bicarbazole emitters: Opposite modulation of circularly polarized luminescence through intramolecular charge-transfer dynamics
Résumé
The rationalization of the molecular parameters that influence the intensity and sign of circularly polarized luminescence (CPL) for chiral emitters is a challenging task and remains of high interest for future chiral optoelectronic applications. In this report, we explore the design of novel chiral donor-acceptor structures based on C2-symmetric bicarbazole systems and compare the influence of the type of chirality, namely axial versus helical, and the electron withdrawing strength of the acceptor units on the resulting photophysical and CPL properties. By using carbonyl-based acceptors with both axial and helical electron donors, CP-Thermally Activated Delayed Fluoresence (TADF) can be obtained, whose efficiency depends on the dihedral angle between the carbazole moieties, related to the axial and helical chirality of the compounds. The latter also impacts the intensity of the CPL, which shows an opposite trend in function of the polarity of the solvent, with notably a strong increase of the luminescence dissymmetry factor, glum, for the helical donor-acceptor compoundsrelated to a subtle reoarganization of the intramolecular charge-transfer process.
Domaines
ChimieOrigine | Fichiers produits par l'(les) auteur(s) |
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