OLED Subpixel Overlap Configuration for Blue Light Extraction
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Solution Overview
Problem
Display devices utilizing organic light emitting diodes (OLEDs) face challenges in achieving high definition due to limitations in light extraction efficiency, particularly with blue light, which has lower luminous efficiency compared to red and green light.
Innovation Solution
The configuration of subpixels in a display device includes overlap areas where the effective light emission area is optimized by positioning subpixels such that blue subpixels have a larger effective area than red and green subpixels, with specific layer structures and aperture designs to enhance light extraction and prevent color mixing and short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If subpixels are arranged with equal effective areas for red, green, and blue, then manufacturing is simplified, but blue light extraction efficiency is insufficient
Solution Approach 1:
The patent applies local quality by assigning different effective light emission areas to different color subpixels. Specifically, blue subpixels are given a larger effective area than red and green subpixels to compensate for the lower luminous efficiency of blue light. This localized adjustment optimizes overall display brightness and color balance without requiring complex global structural changes.
2Manufacturing precision
If additional partitions are added between subpixels to prevent color mixing, then color purity is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts the partition structure from between the subpixels and relocates it to the peripheral regions surrounding the light emitting layers. This allows the light emitting layers to directly overlap and interact, improving light extraction efficiency while the peripheral partitions still provide necessary isolation to prevent color mixing and short circuits.
Solution Approach 2:
The patent transitions from a two-dimensional planar arrangement with partitions between subpixels to a three-dimensional overlapping structure where light emitting layers are positioned at different heights. This vertical dimensionality change allows light to be extracted more efficiently through the overlapping regions while partitions are confined to peripheral areas.
3Illumination intensity
If light emitting layers are positioned to maximize overlap, then light extraction efficiency is improved, but risk of short circuit between electrodes increases
Solution Approach 1:
The patent segments the device into distinct functional regions: central overlap areas where light emitting layers maximize interaction for efficient light extraction, and peripheral partition regions that provide electrical isolation. This segmentation allows the light emitting layers to overlap closely without causing short circuits, as the partitions are positioned to prevent direct contact between electrodes while still permitting optical interaction.
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 improves light extraction efficiency, particularly for blue light, thereby enhancing the overall display definition and preventing reduction in light emission area, allowing for higher definition displays without the need for additional partitions between subpixels.
Implementation Method 1
a display element comprising an organic layer between a pixel electrode and a common electrode, the organic layer including functional layers such as a hole transport layer and an electron transport layer in addition to a light emitting layer
Data Source
AI summary
According to one embodiment, a display device includes a base material, and a display area including a plurality of pixels arrayed in matrix in a first direction and a second direction. Each of the pixels includes a first subpixel, a second subpixel and a third subpixel. Each of the subpixels includes two overlap areas which overlap subpixels which are adjacent in the first direction, and an effective area which contributes display of images. In the first subpixel, neither of the two overlap areas is included in the effective area. In the second subpixel, one of the two overlap areas is included in the effective area, and the other one is not included in the effective area. In the third subpixel, both of the two overlap areas are included in the effective area.