Stable Pure-Green Hyperfluorescent Organic Light-Emitting Diodes with Ultimate Efficiency at High Brightness Toward...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters are key for high-efficiency, wide-color-gamut OLEDs.
• Existing green MR-TADF emitters struggle with color purity, efficiency at high brightness, and device stability.

Purpose of the Study:

• To synthesize and evaluate a novel MR-TADF emitter, DBF-v-DABNA, for improved pure-green OLED performance.
• To address the limitations of current green emitters in achieving high color purity, efficiency, and stability.

Main Methods:

• Molecular design incorporating a rigid meta-dibenzofuran framework and meta-phenyl boron units.
• Fabrication and characterization of hyperfluorescent (HF) bottom-emitting and top-emitting OLED devices.
• Performance evaluation including external quantum efficiency (EQE), color coordinates, brightness stability, and device lifetime.

Main Results:

• DBF-v-DABNA exhibits narrowband pure-green emission (FWHM 16-19 nm) and a high horizontal dipole ratio (94%).
• Achieved EQE > 35% with negligible roll-off, CIEy ≥ 0.73, and brightness stability up to 7.2 × 10^5 cd m^-2 in HF devices.
• Top-emitting devices reached BT.2020 green coordinates with a record current efficiency of 233 cd A^-1 and >600 h lifetime at 5000 cd m^-2.

Conclusions:

• DBF-v-DABNA is a highly promising pure-green emitter for next-generation OLED displays.
• The material overcomes key challenges in efficiency, color purity, and stability for demanding applications.
• Demonstrates potential for ultra-high-definition (UHD) OLED displays requiring superior performance.