Toward a BT.2020 green emitter through a combined multiple resonance effect and multi-lock strategy

Area of Science:

• Materials Science
• Organic Chemistry
• Optoelectronics

Background:

• High color purity and efficiency in green emitters are crucial for advanced display and imaging technologies.
• Existing green emitters often struggle to balance quantum efficiency with color saturation.

Purpose of the Study:

• To design and synthesize novel, rigid green-emitting molecules with high color purity and quantum efficiency.
• To investigate the impact of molecular rigidity and the multiple-resonance (MR) effect on emission properties.
• To evaluate the performance of these emitters in organic light-emitting diodes (OLEDs).

Main Methods:

• Synthesized multiple-resonance (MR)-type boron-nitrogen molecules with phenyl groups linked by bonding and spiro-carbon bridges.
• Utilized a multiple interlocking strategy to suppress molecular vibrations.
• Incorporated the synthesized emitters into phosphorescence OLED devices.
• Measured photophysical properties including full-width at half-maximum (FWHM) and Commission Internationale de L'Eclairage (CIE) y values.

Main Results:

• Developed rigid green emitters exhibiting thermally activated delayed fluorescence.
• Achieved highly pure green emission with a FWHM of 14 nm and a CIE y value of 0.77.
• Demonstrated quantum efficiency and color purity comparable to state-of-the-art quantum dots.
• Fabricated OLEDs with a Broadcast Service Television 2020 color-gamut, a 50% increase in external quantum efficiency, and ultra-high luminescence (5.1 × 10^5 cd/m^2).

Conclusions:

• The developed MR-type B-N molecules represent a significant advancement in green emitter technology.
• The molecular design effectively suppresses vibrations, leading to exceptional color purity and efficiency.
• These emitters enable the creation of the brightest and greenest OLEDs, paving the way for next-generation displays.