OLED Subpixel Dopant Tuning for Wide-Angle Luminance
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Solution Overview
Problem
Light-emitting display devices experience a decrease in luminance when viewed from angles other than directly front due to the optimization of luminance for frontal viewing, leading to luminance deterioration as the viewing angle increases.
Innovation Solution
The use of a light-emitting display device structure with different dopants in sub-pixels of the same color, where the electroluminescence peak wavelengths of the dopants differ by 1 nm to 40 nm, and the full widths at half maximum (FWHMs) are varied to extend the electroluminescence effects, ensuring luminance is maintained across different viewing angles by superimposing the electroluminescence graphs of the first and second light-emitting layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light-emitting elements are optimized for frontal luminance, then frontal luminance is improved, but luminance deteriorates as viewing angle increases
Solution Approach 1:
The invention divides the light-emitting display into multiple regions (first region and second region) with different light-emitting layers. Each region has light-emitting elements optimized for different viewing angle characteristics, allowing the display to maintain luminance across various viewing angles by combining the outputs of these segmented regions.
Solution Approach 2:
Different light-emitting layers with distinct dopants are applied to different regions of the display. The first light-emitting layer has dopants optimized for frontal viewing, while the second light-emitting layer has dopants optimized for off-angle viewing. This local differentiation allows each region to contribute its strength, resolving the contradiction between frontal luminance optimization and viewing angle adaptability.
2Adaptability or versatility
If different dopants are used in light-emitting layers, then viewing angle characteristics are improved, but device complexity increases
Solution Approach 1:
The invention uses a common electrode structure that serves all light-emitting layers, and shared electrode configurations that work across both regions. This multi-functional design allows the system to achieve different viewing angle characteristics through material composition rather than structurally complex arrangements, thereby reducing overall device complexity while maintaining viewing angle adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents or alleviates luminance deterioration when viewed from various angles, maintaining high luminance efficiency and minimizing color deviation, thus enhancing the display's performance and usability.
Implementation Method 1
a first light-emitting layer having a first dopant on the first lower electrode of the first region, a second light-emitting layer on the second lower electrode of the second region, the second light-emitting layer having a second dopant different form the first dopant
Data Source
AI summary
A light-emitting display device includes: a substrate including a first region and a second region spaced apart from each other, a first lower electrode at the first region, a second lower electrode at the second region, a first light-emitting layer having a first dopant on the first lower electrode of the first region, a second light-emitting layer on the second lower electrode of the second region, the second light-emitting layer having a second dopant different form the first dopant, the second light-emitting layer being configured to emit a light of a same color as that of the first light-emitting layer, and a common electrode on the first and second light-emitting layers, over the first and second regions.