Highly Efficient Solution-Processed Blue Phosphorescent Organic Light-Emitting Diodes Based on Co-Dopant and Co-Host...

Area of Science:

• Organic electronics
• Materials science
• Device physics

Background:

• Low-lying HOMO levels and poor interfacial miscibility hinder hole injection in blue PhOLEDs.
• Triplet-triplet annihilation (TTA) and triplet-polaron annihilation (TPA) limit the efficiency of blue phosphorescent organic light-emitting diodes (PhOLEDs).

Purpose of the Study:

• To enhance the efficiency of solution-processed blue PhOLEDs.
• To address challenges in hole injection and efficiency losses in blue PhOLEDs.

Main Methods:

• Design of co-host structures utilizing TcTa and mCPPO1 for improved hole transport and carrier balance.
• Introduction of a dual-dopant system with FIr6 and FCNIrPic to facilitate hole injection and energy transfer.
• Investigation of microcavity effects by varying the electron transport layer (ETL) thickness.

Main Results:

• The co-host and co-dopant strategy effectively improved carrier distribution and reduced TPA.
• The dual-dopant system, particularly FCNIrPic, enhanced hole injection and energy transfer processes.
• A microcavity effect was observed, influencing the electroluminescence (EL) spectrum with varying ETL thickness.
• Achieved maximum current efficiency (CE) of 20.47 cd/A, power efficiency (PE) of 11.96 lm/W, and external quantum efficiency (EQE) of 11.62%.

Conclusions:

• The developed co-host and co-dopant approach significantly boosts the performance of solution-processed blue PhOLEDs.
• Understanding and controlling microcavity effects is crucial for optimizing EL spectrum and device efficiency.
• This work presents a viable strategy for achieving high-efficiency blue PhOLEDs through solution processing.