Multi-mode Organic Light-Emitting Diode to Suppress the Viewing Angle Dependence.

Area of Science:

• Materials Science
• Optoelectronics
• Display Technology

Background:

• Typical top-emitting organic light-emitting diodes (OLEDs) suffer from strong microcavity effects due to reflective electrodes.
• These microcavity effects lead to significant viewing angle-dependent color shifts and limit the permissible thickness of organic layers.

Purpose of the Study:

• To design a new OLED structure that overcomes the limitations imposed by microcavity effects.
• To achieve angle-independent color performance and flexible organic layer thickness in OLED devices.

Main Methods:

• Introduction of a multi-mode OLED structure incorporating dual-dielectric spacer layers.
• Extension of the effective cavity length by over 10 times compared to conventional designs.
• Demonstration using a white OLED emitter to evaluate angular performance.

Main Results:

• Complete elimination of the intrinsic microcavity effect.
• Demonstrated negligible angular chromaticity shift (Δuv = 0.006 from 0 to 70°) in a white multi-mode OLED.
• Achieved a Lambertian emission profile, indicating uniform light distribution.

Conclusions:

• The proposed multi-mode OLED structure effectively mitigates microcavity issues, offering superior angular color stability.
• The design provides significant freedom in selecting organic layer thicknesses.
• This structure is highly promising for applications in large-area displays and solid-state lighting.