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Toward Circularly Polarized Luminescence from Inherently Chiral Inverted Singlet-Triplet Chromophores
Simone Veglianti1, Alessandro Michieletti1, Daniele Padula1
1Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy.
ACS Materials Letters
|October 10, 2025
Summary
Researchers explored chiral molecules with inverted singlet-triplet energies (IST) for circularly polarized luminescence (CPL). They optimized structures for potential use in circularly polarized organic light-emitting diodes (CP-OLEDs).
Area of Science:
- Organic Chemistry
- Materials Science
- Photophysics
Background:
- Growing interest in molecules violating Hund's rule, exhibiting inverted singlet-triplet energy (ΔEST < 0).
- This inversion accelerates reverse intersystem crossing, crucial for thermally activated delayed fluorescence (TADF).
- Circularly Polarized Luminescence (CPL) is a developing field for advanced optical applications.
Purpose of the Study:
- To computationally investigate chiral inverted singlet-triplet (IST) molecules for Circularly Polarized Luminescence (CPL).
- To explore functionalization of triangulene and pentalene chromophores for chirality and IST properties.
- To assess inherently chiral, nonplanar chromophores and their potential for enantiomer separation and stability.
Main Methods:
- Multiconfigurational calculations to determine singlet-triplet energy (ΔEST) and electronic properties.
- Computational functionalization of triangulene and pentalene scaffolds with chiral groups.
- Assessment of racemization barriers and optimization of structures for CPL and IST energetics.
Main Results:
- Minimal chiral functionalization of triangulene and pentalene preserved negative ΔEST.
- Exploration of nonplanar, inherently chiral extended triangulenes showed promise for CPL.
- Optimized structures demonstrated a high racemization barrier, strong CPL, and retained IST energetics.
Conclusions:
- Chiral IST molecules can be designed to exhibit strong CPL, opening new avenues for IST emitters.
- Optimized structures show suitability for circularly polarized organic light-emitting diode (CP-OLED) applications.
- This study provides a computational foundation for developing novel chiral materials for optoelectronics.
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