Rationally Designed Multi-Resonance Emitters Achieving >42% EQE in Ultra-Green OLEDs

Area of Science:

• Organic Electronics
• Materials Science
• Display Technology

Background:

• Achieving narrow-band, efficient green emission for ultra-high-definition displays is challenging.
• Current limitations include balancing emission characteristics with exciton harvesting and light outcoupling.

Purpose of the Study:

• To introduce a molecular design strategy for high-performance ultra-green organic light-emitting diodes (OLEDs).
• To overcome limitations in achieving narrow emission, efficient exciton utilization, and high light outcoupling.

Main Methods:

• Employed a fluorene bridge to rigidify a BNCz-based emitter core.
• Incorporated a planar N-phenyl-carbazol-3-yl group to enforce horizontal dipole orientation.
• Utilized steric shielding to prevent aggregation and quenching.

Main Results:

• Achieved ultragreen emission with CIE coordinates near the BT.2020 standard.
• Attained a maximum external quantum efficiency (EQE) of 39.6% for the emitter.
• Demonstrated a record 42.2% EQE in a device with a thermally activated delayed fluorescence sensitizer, showing suppressed roll-off.

Conclusions:

• The molecular design principle enables simultaneous optimization of emission color, exciton harvesting, and light outcoupling.
• This approach is vital for developing next-generation high-resolution OLED displays.
• The study provides a pathway for advanced organic electronic emitters.