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Circularly Polarized Luminescence from an Inverted Singlet-Triplet Chiral Dye
Alessandro Altinier1, Ewa Machalska2, Ilaria Fortunati1
1Dipartimento di Scienze Chimiche, Università degli Studi di Padova, via Marzolo 1, 35131, Padova, Italy.
Journal of the American Chemical Society
|September 11, 2025
Summary
Researchers report the first circularly polarized light emission from chiral molecules with an inverted singlet-triplet gap. This breakthrough offers potential for advanced optoelectronic devices like circularly polarized organic light-emitting diodes (OLEDs).
Area of Science:
- Organic Chemistry
- Materials Science
- Photophysics
Background:
- Molecules with inverted singlet-triplet gaps (ΔEST < 0) are promising for optoelectronics.
- Previous research lacked single-molecule circularly polarized light emission (CPL) from chiral dyes with inverted gaps.
Purpose of the Study:
- To achieve the first CPL from a chiral molecule with an inverted singlet-triplet gap.
- To explore the potential of functionalized heptazine cores for optoelectronic applications.
Main Methods:
- Computational screening to identify suitable molecular designs.
- Synthesis of chiral molecules based on an achiral heptazine core.
- Photophysical characterization (temperature-dependent spectra, decay profiles) and chiroptical measurements.
Main Results:
- Confirmed inverted singlet-triplet gap in both achiral and chiral heptazine derivatives.
- Observed CPL with dissymmetry factor (glum) values around 10-3.
- Achieved promising photoluminescence quantum yields.
Conclusions:
- Demonstrated the first CPL from chiral molecules with inverted singlet-triplet gaps.
- Highlighted the potential of these novel materials for circularly polarized OLEDs and other optoelectronic applications.
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