One-Step Carbonyl-Locking Strategy for Multi-Resonance Emitters Enabling Efficient, Narrowband Blue OLEDs.

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Narrowband blue emitters are crucial for achieving wide color gamut in organic light-emitting diodes (OLEDs).
• Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters offer a promising pathway to efficient and spectrally pure light emission.

Purpose of the Study:

• To design and synthesize novel MR-TADF emitters with improved efficiency and narrowband blue emission.
• To investigate the effect of incorporating an electron-deficient carbonyl group on the photophysical properties and device performance of MR-TADF molecules.

Main Methods:

• Strategic incorporation of an electron-deficient carbonyl lock into the classical MR-TADF skeleton via a one-step carbonylation reaction.
• Synthesis and characterization of proof-of-concept emitters, CO-BCzBN and CO-DABNA.
• Fabrication and testing of sensitized OLED devices using the developed emitters.

Main Results:

• The new design strategy reduced intramolecular charge-transfer intensity, leading to blue-shifted emission and enhanced molecular planarity and rigidity.
• Achieved narrowband blue emission with full widths at half maximum (FWHMs) of 16 nm for CO-BCzBN and 18 nm for CO-DABNA.
• OLED devices demonstrated excellent blue electroluminescence with high external quantum efficiencies (EQEmax) of 37.9% and 22.8%.

Conclusions:

• The developed CO-BCzBN and CO-DABNA represent the first blue boron/nitrogen/carbonyl hybrid MR-TADF emitters.
• The carbonyl lock strategy effectively narrows emission spectra and enhances molecular rigidity for efficient blue OLEDs.
• These emitters show significant potential for next-generation wide color gamut OLED displays.