Sequential Multiple Borylation Toward an Ultrapure Green Thermally Activated Delayed Fluorescence Material.

Area of Science:

• Materials Science
• Organic Chemistry
• Optoelectronics

Background:

• Multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters are crucial for high-performance organic light-emitting diodes (OLEDs) due to their narrow emission and efficient exciton utilization.
• The exploration of MR-TADF emitters is limited by the lack of versatile synthetic strategies.

Purpose of the Study:

• To develop a novel synthetic protocol for accessing new chemical space in MR-TADF emitters.
• To demonstrate the efficacy of the developed method using a proof-of-concept material.

Main Methods:

• Sequential multiple borylation reaction for synthesizing MR-TADF materials.
• Fabrication and characterization of OLED devices utilizing the synthesized MR-TADF emitter.

Main Results:

• A novel MR-TADF material, ω-DABNA, was synthesized, exhibiting narrowband green TADF (FWHM 22 nm) and a small singlet-triplet energy gap (13 meV).
• The resulting OLED device demonstrated electroluminescence at 512 nm with CIE coordinates (0.13, 0.73) and a high external quantum efficiency (EQE) of 31.1%.
• The device exhibited excellent operational stability with minimal efficiency roll-off, maintaining an EQE of 29.4% at 1000 cd m⁻².

Conclusions:

• The developed sequential borylation reaction significantly expands the accessible chemical space for MR-TADF emitters.
• The proof-of-concept material demonstrates the potential of this synthetic approach for creating high-performance OLEDs with superior efficiency and stability.