Achieving Record External Quantum Efficiency of 11.5 % in Solution-Processable Deep-Blue Organic Light-Emitting...

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• High-performance, solution-processable deep-blue emitters are crucial for ultra-high-definition displays.
• Existing deep-blue materials with hybridized local and charge-transfer (HLCT) excited states often lack the necessary properties for efficient solution processing due to rigid and planar structures.

Purpose of the Study:

• To design and synthesize novel deep-blue solution-processable emitters with improved performance for display applications.
• To investigate the impact of incorporating rigid imide aliphatic rings on the properties of HLCT emitters.

Main Methods:

• Synthesized four novel deep-blue emitters by attaching rigid imide aliphatic rings to an HLCT emitting core.
• Fabricated and characterized solution-processable organic light-emitting diodes (OLEDs) using these novel emitters.
• Evaluated device performance, including external quantum efficiency (EQE), emission peak, color purity, and Commission International de l'Eclairage (CIE) coordinates.

Main Results:

• The novel emitters exhibit enhanced solubility, thermal properties, and morphological stability.
• Photoluminescence efficiency was improved, charge carrier transport was balanced, and aggregation-caused quenching was inhibited.
• The fabricated OLEDs achieved a maximum external quantum efficiency (EQEmax) of 11.5% with an emission peak at 456 nm and excellent color purity (CIEy=0.09).
• These results represent state-of-the-art performance for solution-processable blue OLEDs utilizing the "hot exciton" mechanism.

Conclusions:

• The strategy of attaching rigid imide aliphatic rings effectively enhances the performance of deep-blue HLCT emitters for solution processing.
• This approach provides a new pathway for developing highly efficient, solution-processable deep-blue organic luminescent materials for advanced display technologies.