Simultaneous enhancement of thermally activated delayed fluorescence and photoluminescence quantum yield via homoconjugation

29 October 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


A fundamental problem facing thermally activated delayed fluorescence (TADF) is to overcome the paradox of efficient electronic transitions and a narrow singlet-triplet energy gap (ΔEST) in a single luminophore. We present a quinoxaline-based TADF iptycene as the first clear example that homoconjugation can be harnessed as a viable design strategy toward this objective. Homoconjugation was introduced in an established TADF luminophore by trimerization through an iptycene core. This homoconjugation was confirmed by electrochemistry. As a direct consequence of homoconjugation we observed synergistic improvements to photoluminescence quantum yield (ΦPL), radiative rate of singlet decay (krS), delayed fluorescence lifetime (τTADF), and rate of reverse intersystem crossing (krISC), while narrowing the ΔEST. The cooperative enhancement is rationalised with TD-DFT calculations including spin-orbit coupling (SOC). A facile synthesis of this system, and the ubiquity of the pyrazine motif in state-of-the-art TADF materials across the electromagnetic spectrum, leads to a great potential for generality.


Thermally activated delayed fluorescence
Photoluminescence Quantum Yield

Supplementary materials

Supplementary Information
1. Experimental Section 2. Synthetic Methods 3. NMR Spectra 4. X-ray Crystallography 5. Electrochemistry 6. Density Functional Theory 7. Photophysical Calculations 8. Steady State Photophysics and Additional Absorption Spectra in Solution 9. Photophysics in Zeonex Matrix 10. Time-resolved Photophysics in Solution 11. Photophysics in OLED Host 12. OLED Devices 13. References


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