High-Efficiency Solution-Processed Organic Light-Emitting Diodes with Tetradentate Platinum(II) Emitters

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Organic light-emitting diodes (OLEDs) are crucial for advanced display and lighting technologies.
• Phosphorescent emitters, particularly those based on platinum (Pt) complexes, offer high efficiency.
• Solution-processing methods are desirable for cost-effective OLED fabrication.

Purpose of the Study:

• To investigate the impact of organic host materials on the performance of solution-processed phosphorescent platinum (Pt) OLEDs.
• To evaluate newly developed tetradentate Pt(II) emitters and bipolar organic hosts.
• To identify optimal emitter-host combinations for high-efficiency OLEDs.

Main Methods:

• Fabrication and characterization of solution-processed OLED devices.
• Systematic variation of four tetradentate Pt(II) emitters (including tetra-Pt-S2 and tetra-Pt-S3) and three bipolar organic hosts (m-TPAPy, o-TPAPy, o-CzPy).
• Analysis of electroluminescent performance, external quantum efficiency (EQE), and luminance.

Main Results:

• The tetra-Pt-S3 emitter demonstrated the best performance due to its bulky structure, high quantum yield, and solubility.
• An OLED device utilizing tetra-Pt-S3 emitter and m-TPAPy host achieved a high external quantum efficiency (EQE) of 22.4% at 4 wt% dopant concentration.
• The device maintained a high EQE of 21.0% even at a luminance of 1000 cd m⁻².

Conclusions:

• Tetradentate Pt(II) complexes, especially tetra-Pt-S3, are promising emitters for high-efficiency solution-processed OLEDs.
• The choice of bipolar organic host significantly influences OLED performance, with m-TPAPy proving effective.
• The developed Pt-OLEDs exhibit excellent efficiency and stability, suitable for practical applications.