Optimum thickness of epsilon negative tri-metal layer electrodes for maximizing OLED outcoupling efficiency

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Transparent electrodes are critical for efficient light extraction in organic light-emitting diodes (OLEDs).
• The electrical and optical properties of electrodes significantly impact OLED performance.
• Conventional indium tin oxide (ITO) electrodes have limitations in certain applications.

Purpose of the Study:

• To evaluate the impact of epsilon negative tri-metal layer (TML) electrode thickness on red phosphorescent OLED (PHOLED) performance.
• To investigate the optical microcavity effect induced by TML electrodes.
• To compare the efficiency of TML-based PHOLEDs with conventional ITO-based PHOLEDs.

Main Methods:

• Theoretical studies were conducted to understand the underlying physics.
• Full-wave simulations were employed to model light propagation and interaction.
• Experimental fabrication and characterization of red PHOLEDs with varying TML thicknesses were performed.

Main Results:

• The thickness of the TML electrode was optimized for enhanced performance.
• An optical microcavity effect was observed and utilized.
• The optimized TML-based red PHOLED achieved an external quantum efficiency (EQE) of 17.6%.

Conclusions:

• TML electrodes offer a significant improvement over conventional ITO electrodes for PHOLEDs.
• The optimized TML-based red PHOLED showed a ~40% higher EQE compared to ITO-based devices.
• This work demonstrates the potential of TMLs for advancing OLED technology.