AIE-Active Circularly Polarized Thermally Activated Delayed Fluorescence Emitters for Stable Solution-Processed...

Area of Science:

• Materials Science
• Organic Electronics
• Photonics

Background:

• Circularly polarized organic light-emitting diodes (CP-OLEDs) are crucial for naked-eye 3D displays.
• Current fabrication methods predominantly rely on vacuum deposition, limiting scalability and cost-effectiveness.
• Developing efficient solution-processed CP-OLEDs with suppressed efficiency roll-off is a significant challenge.

Purpose of the Study:

• To design and synthesize novel thermally activated delayed fluorescence (TADF) enantiomers for solution-processed CP-OLEDs.
• To investigate the impact of isomer engineering on molecular properties and device performance.
• To achieve efficient and stable circularly polarized electroluminescence (CP-EL) in solution-processed devices.

Main Methods:

• Synthesis of two pairs of TADF enantiomers, (R/S)-N-5-TPA and (R/S)-N-4-TPA, via isomer engineering, incorporating phthalimide (acceptor) and tri-phenylamine (donor) units.
• Incorporation of aggregation-induced emission (AIE) properties into the synthesized molecules.
• Fabrication of CP-OLED devices using a solution-processing technique.

Main Results:

• The synthesized TADF enantiomers exhibited aggregation-induced emission (AIE) properties.
• Solution-processed CP-OLEDs demonstrated vivid blue-green and green emissions.
• Achieved high performance metrics including maximum current efficiencies of 7.4 and 29.6 cd A⁻¹, external quantum efficiencies of 2.7% and 10.2%, and low efficiency roll-off (3.7% and 16.7%).
• Observed significant CP-EL signals with gEL values up to ±1.25×10⁻³.

Conclusions:

• The developed TADF enantiomers are suitable for efficient solution-processed CP-OLEDs.
• Isomer engineering is an effective strategy for tuning molecular properties and enhancing device performance.
• These findings pave the way for advanced 3D display applications using cost-effective fabrication methods.