Top-Emission OLED Reflective Regions Reduce Color Shift
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Solution Overview
Problem
Conventional top-emission active matrix electroluminescent devices suffer from color shift at different viewing angles due to the micro-cavity effect, which affects the emission luminance and overall display quality.
Innovation Solution
The introduction of multiple reflective regions under the electroluminescent layer with varying optical path lengths, along with a passivation layer, helps to compensate for the light emission and reduce color shift by adjusting the thickness of the passivation layer and overlapping reflective regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional top-emission active matrix electroluminescent device structure is used, then emission luminance is improved through micro-cavity effect, but color shift at different viewing angles occurs
Solution Approach 1:
The reflective layer is segmented into multiple reflective regions (first reflective layer region, second reflective layer region, and third reflective layer region) with different optical path lengths. Each reflective region reflects light with different optical paths, and their combined effect compensates for the micro-cavity effect-induced color shift while maintaining emission luminance.
2Ease of manufacture
If multiple reflective regions with different optical path lengths are introduced, then color shift is reduced, but device structure becomes more complex
Solution Approach 1:
Multiple reflective regions with different optical path lengths are merged into a single integrated reflective layer structure. This combining approach achieves color shift compensation through the collective effect of different optical paths while avoiding the need for separate, complex compensating structures.
Solution Approach 2:
The reflective layer serves multiple functions: it provides overall light reflection for emission luminance enhancement and simultaneously contains multiple reflective regions that compensate for color shift. This multi-functionality reduces the need for additional separate components.
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 configuration effectively reduces color shift at different viewing angles, enhancing the micro-cavity effect and improving the display's luminance and color consistency.
Implementation Method 1
By reflecting part of the light from the electroluminescent layer through each reflective region, the reflected light can emit upward
Implementation Method 2
an electroluminescent layer
Implementation Method 3
This produces a micro-cavity effect between the transparent cathode layer 101 and the transparent anode layer 103. On one hand, the micro-cavity effect improves emission luminance
Data Source
AI summary
This invention provides a top-emission active matrix electroluminescent device including a substrate and a plurality of pixel areas formed within a display area of the substrate. Each of the pixel areas includes at least one sub-pixel area comprising at least, from top to bottom: a first conductive electrode layer, an electroluminescent layer, a second conductive electrode layer, a first reflective layer region, and a second reflective layer region. The first reflective layer region and second reflective layer region overlap each other in part. Some of the light rays emitted from the electroluminescent layer are reflected by the first reflective layer region and second reflective layer region, respectively, and are then directed upwards. The reflected light rays compensate the top-emitting light rays also emitted from the electroluminescent layer, reducing color shifts at different viewing angles due to the micro-cavity effect.