High-Performance Coemissive Blue Organic Light-Emitting Diodes Combining Phosphorescence and Multiresonance...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Organic light-emitting diodes (OLEDs) are crucial for displays and lighting.
• Achieving efficient, durable, and pure deep blue emission remains a significant challenge in OLED technology.
• Phosphor-sensitized OLEDs (PS-OLEDs) offer a promising route to overcome these limitations by combining different emitter types.

Purpose of the Study:

• To develop and investigate novel Pt(II) phosphors and multiresonance thermally activated delayed fluorescence (MR-TADF) emitters for PS-OLEDs.
• To systematically study the emission properties and energy transfer mechanisms in PS-OLEDs utilizing these new materials.
• To enhance the efficiency, durability, and color purity of deep blue emission in OLED devices.

Main Methods:

• Synthesis and characterization of a tetradentate Pt(II)-based blue star phosphor (PtON-PTB).
• Development of a novel MR-TADF emitter (M-t-DABNA-d) with a stabilized deuterated methyl group.
• Fabrication and performance evaluation of bottom- and top-emission PS-OLED devices incorporating these emitters.

Main Results:

• The newly developed PtON-PTB and M-t-DABNA-d significantly improved PS-OLED performance.
• A bottom-emission PS-OLED achieved a maximum external quantum efficiency (EQEmax) of 21.3% and a lifetime (LT90) of 55 hours with deep blue CIE coordinates (0.14, 0.19).
• A top-emission PS-OLED demonstrated a maximum EQE of 24.2% and a lifetime (LT90) of 93 hours with CIE coordinates (0.12, 0.10).

Conclusions:

• The synergistic integration of Pt(II) phosphors and MR-TADF emitters enables high-performance blue PS-OLEDs.
• The developed materials and device architectures offer a promising pathway for efficient and durable deep blue OLEDs.
• This work highlights the potential of coemissive strategies in advancing OLED technology for display applications.