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Scale-up Chemical Synthesis of Thermally-activated Delayed Fluorescence Emitters Based on the Dibenzothiophene-S,S-Dioxide Core
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Nido-Carboranes: Donors for Thermally Activated Delayed Fluorescence
Nguyen Van Nghia1, Saibal Jana2, Surendran Sujith1
1Department of Chemistry and EHSRC, University of Ulsan, Ulsan, 44610, Republic of Korea.
Angewandte Chemie (International Ed. in English)
|August 10, 2018
Summary
Researchers designed novel luminescent compounds using nido-carboranes for efficient thermally activated delayed fluorescence (TADF). Some compounds also exhibit aggregation-induced emission (AIE) with TADF properties, paving the way for advanced materials.
Area of Science:
- Materials Science
- Organic Chemistry
- Photochemistry
Background:
- Thermally activated delayed fluorescence (TADF) is crucial for efficient organic light-emitting diodes (OLEDs).
- Designing molecules with small singlet-triplet energy splitting (ΔEST) is key for achieving TADF.
- Nido-carboranes offer unique structural and electronic properties for molecular design.
Purpose of the Study:
- To develop a new design strategy for nido-carborane-based luminescent compounds exhibiting TADF.
- To investigate the structure-property relationships influencing TADF and aggregation-induced emission (AIE) in these novel compounds.
Main Methods:
- Synthesis of donor-acceptor compounds by appending nido-carboranes to a dimesitylphenylborane acceptor.
- Systematic variation of the 8-R group on the nido-carborane and its substitution position (meta or para).
- Photophysical characterization to determine TADF properties, ΔEST, and emission lifetimes.
Main Results:
- Novel nido-carborane-based donor-acceptor compounds were successfully synthesized.
- A highly twisted donor-acceptor arrangement was achieved through bulky 8-R groups and meta-substitution, leading to small ΔEST (<0.05 eV).
- Efficient TADF with microsecond lifetimes was observed; compounds nido-m2 and -m3 showed both AIE and TADF.
Conclusions:
- The proposed approach enables the design of nido-carborane-based TADF emitters.
- The steric and electronic effects of nido-carborane substituents are critical for tuning photophysical properties.
- The discovery of AIE-active TADF materials opens new avenues for advanced optoelectronic applications.
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