Intramolecular Hydrogen Bonding Rigidifying Flexible Bridge for Solution- and Vacuum-Processed TSCT-TADF Emitters

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Efficient organic light-emitting diodes (OLEDs) require optimized molecular design for charge transfer.
• Thermally activated delayed fluorescence (TADF) emitters are crucial for high OLED performance.
• Achieving strong donor-acceptor face-to-face stacking is key for through-space charge transfer (TCT) TADF.

Purpose of the Study:

• To propose a novel design strategy for TCT-TADF emitters.
• To enhance donor-acceptor stacking through molecular rigidity.
• To investigate the photophysical properties and device performance of the designed emitter.

Main Methods:

• Molecular design incorporating intramolecular hydrogen bonds (IHBs) for rigidity.
• Synthesis and characterization of the ACE-CN emitter.
• Fabrication and testing of OLED devices using solution and vacuum processing.

Main Results:

• The ACE-CN emitter features a planarized benzyl methyl ether bridge stabilized by C-H···O IHBs.
• Achieved a high photoluminescence quantum efficiency (PLQY) of 93%.
• Demonstrated high external quantum efficiencies (EQEs) of 11.8% (solution-processed) and 24.7% (vacuum-processed).

Conclusions:

• The proposed IHB strategy effectively couples molecular fragments, enhancing rigidity and promoting face-to-face stacking.
• ACE-CN exhibits excellent photophysical properties and high device efficiencies, validating the design approach.
• This strategy offers a promising pathway for developing advanced TCT-TADF emitters for OLED applications.