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- Title
Fast and Tunable Phosphorescence from Organic Ionic Crystals.
- Authors
Partanen, Iida; Al‐Saedy, Omar; Eskelinen, Toni; Karttunen, Antti J.; Saarinen, Jarkko J.; Mrózek, Ondrej; Steffen, Andreas; Belyaev, Andrey; Chou, Pi‐Tai; Koshevoy, Igor O.
- Abstract
Crystalline diphosphonium iodides [MeR2P‐spacer‐R2Me]I with phenylene (1, 2), naphthalene (3, 4), biphenyl (5) and anthracene (6) as aromatic spacers, are photoemissive under ambient conditions. The emission colors (λem values from 550 to 880 nm) and intensities (Φem reaching 0.75) are defined by the composition and substitution geometry of the central conjugated chromophore motif, and the anion‐π interactions. Time‐resolved and variable‐temperature luminescence studies suggest phosphorescence for all the titled compounds, which demonstrate observed lifetimes of 0.46–92.23 μs at 297 K. Radiative rate constants kr as high as 2.8×105 s−1 deduced for salts 1–3 were assigned to strong spin‐orbit coupling enhanced by an external heavy atom effect arising from the anion‐π charge‐transfer character of the triplet excited state. These rates of anomalously fast metal‐free phosphorescence are comparable to those of transition metal complexes and organic luminophores that utilize triplet excitons via a thermally activated delayed fluorescence mechanism, making such ionic luminophores a new paradigm for the design of photofunctional and responsive molecular materials.
- Subjects
DELAYED fluorescence; PHOSPHORESCENCE; IONIC crystals; SPIN-orbit interactions; LUMINOPHORES; TRANSITION metal complexes; EXCITON theory
- Publication
Angewandte Chemie, 2023, Vol 135, Issue 36, p1
- ISSN
0044-8249
- Publication type
Article
- DOI
10.1002/ange.202305108