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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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Molecular Engineering Towards Efficient Aggregation-Induced Delayed Fluorescence Luminogens as Emitters and
Hongbo Wang1,2, Peng Zou1, Letian Xu1
1State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China.
Chemistry, an Asian Journal
|August 21, 2024
Summary
New aggregation-induced delayed fluorescence (AIDF) materials achieve over 35% external quantum efficiency in organic light-emitting diodes (OLEDs). These materials offer high thermal stability and efficient light emission, showing great potential for advanced OLED applications.
Area of Science:
- Materials Science
- Organic Electronics
- Photophysics
Background:
- Achieving high external quantum efficiencies (ηext,maxs) over 30% in organic light-emitting diodes (OLEDs) using thermally-activated delayed fluorescence (TADF) materials is challenging.
- This requires simultaneous optimization of reverse intersystem crossing (RISC), photoluminescence quantum yield (ΦPL), and optical out-coupling efficiency (Φout).
Purpose of the Study:
- To design and synthesize novel aggregation-induced delayed fluorescence (AIDF) luminogens for high-performance OLEDs.
- To evaluate their potential as both light-emitting materials and sensitizers in hyperfluorescence OLEDs.
Main Methods:
- Design and synthesis of two AIDF luminogens (XTCz-2 and XTCz-3) using xanthone as an electron acceptor and substituted carbazole as donors.
- Characterization of their thermal stability, photoluminescence quantum yield (ΦPL), reverse intersystem crossing (RISC) rates, and dipole orientation.
- Fabrication and testing of OLED devices using these materials and evaluation as sensitizers in hyperfluorescence OLEDs.
Main Results:
- XTCz-2 and XTCz-3 exhibit high thermal stability (439-560 °C), excellent ΦPLs (84-88%), and fast RISC rates (1.9×105-4.2×105 s-1).
- These materials demonstrate a preference for horizontal dipole orientation, leading to high Φouts and achieving state-of-the-art electroluminescence (EL) performances with ηext,maxs up to 35.0%.
- XTCz-3 as a sensitizer in hyperfluorescence OLEDs yields narrow EL spectra and high ηext,maxs of up to 33.8% with low efficiency roll-offs.
Conclusions:
- The developed AIDF luminogens show significant potential for high-performance OLED applications due to their excellent photophysical properties and device efficiencies.
- These materials are promising for use as both emissive layers and sensitizers in advanced OLED architectures, including hyperfluorescence devices.
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