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Pivotal role of transition density in circularly polarized luminescence† † Electronic supplementary information (ESI) available: Theoretical background, electric dipole transition moment, magnetic dipole transition moment, transition density distribution, natural transition orbital and structural data. List of compounds include representative organic chiral emitters explored in this study. See DOI: https://doi.org/10.1039/d3sc01809a

ABSTRACT: Realizing high luminescence dissymmetry factor (g) in circularly polarized luminescence (CPL) materials remains a big challenge, which necessitates understanding systematically how their molecular structure controls the CPL. Here we investigate representative organic chiral emitters with different transition density distributions and reveal the pivotal role of transition density in CPL. We rationalize that to obtain large g-factors, two conditions should be simultaneously satisfied: (i) the transition density for the S1 (or T1)-to-S0 emission must be delocalized over the entire chromophore; and (ii) the chromophore inter-segment twisting must be restricted and tuned to an optimal value (∼50°). Our findings offer molecular-level insights into the CPL of organic emitters, with potential applications in the design of chiroptical materials and systems with strong CPL effects. Transition density delocalization allows stable control of CPL by twisting chromophore segments. However, when transition density is localized, CPL cannot be controlled by such twisting and can be weakened by molecular vibrations.

SUBMITTER: Chen Z

PROVIDER: S-EPMC10246659 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature

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