OLED Micro-Cavity Design for Uniform Luminance and Color Purity
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Solution Overview
Problem
Organic light emitting devices face challenges in achieving uniform light emitting efficiency across different color pixels, leading to inaccurate color reproduction due to varying light emitting efficiencies of materials used, and the implementation of micro-cavities increases fabrication complexity and alters the white spectrum.
Innovation Solution
The organic light emitting device employs a substrate with a transflective member forming a micro-cavity, where the optical path lengths of red, blue, and green pixels are optimized to satisfy specific wavelength conditions, and the white pixel lacks a micro-cavity, allowing light to pass directly through the pixel electrode and substrate, reducing absorption and enhancing light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If micro-cavities are implemented in each pixel to improve light emitting efficiency and color reproducibility, then luminance and color accuracy are improved, but fabrication complexity increases and white spectrum is altered
Solution Approach 1:
The display device segments pixels into two types: color pixels (R, G, B) with micro-cavities for enhanced color reproducibility, and white pixels without micro-cavities for simplified fabrication and accurate white spectrum. This segmentation resolves the contradiction by applying micro-cavities only where needed for color enhancement while avoiding them in white pixels where they would complicate fabrication and alter the spectrum.
Solution Approach 2:
Different optical structures are applied to different pixel types based on their specific requirements: color pixels receive micro-cavity structures to enhance their color emission, while white pixels maintain a simpler structure without micro-cavities to preserve their broad spectrum and simplify fabrication. This local differentiation resolves the contradiction between improved color accuracy and reduced fabrication complexity.
2Illumination intensity
If micro-cavities are added to each pixel to enhance luminance, then light emitting efficiency is improved, but the number of fabrication processes increases
Solution Approach 1:
The pixel array is segmented into color pixels requiring micro-cavities for luminance enhancement and white pixels that achieve sufficient luminance without them. This segmentation allows the fabrication process to apply micro-cavity structures only to color pixels, reducing the overall number of fabrication steps and improving productivity while still enhancing luminance where needed.
Solution Approach 2:
Instead of applying micro-cavities to all pixels (excessive action), the invention applies them partially only to color pixels where luminance enhancement is most beneficial. This partial application reduces fabrication complexity and process time while still achieving the desired luminance improvement in the critical color pixels.
3Illumination intensity
If micro-cavities are used in white pixels to improve light efficiency, then luminance is enhanced, but the white spectrum is altered
Solution Approach 1:
The micro-cavity structure is extracted (removed) from white pixels while being retained in color pixels. This extraction resolves the contradiction by eliminating the element that would alter the white spectrum while preserving the luminance enhancement benefit in color pixels where the micro-cavity is needed for color accuracy.
Solution Approach 2:
Different optical structures are applied to different pixel types: white pixels have a simple structure without micro-cavities to preserve their broad, accurate white spectrum, while color pixels have micro-cavities to enhance their color emission. This local differentiation resolves the contradiction between luminance enhancement and spectrum accuracy for white pixels.
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 simplifies the fabrication process by maintaining uniform optical path lengths for red and blue pixels, improves light emitting efficiency, and ensures accurate color reproduction by eliminating the need for micro-cavities in white pixels, thereby enhancing luminance and color purity.
Implementation Method 1
light is repeatedly reflected between a reflection layer and a transflective layer that are separated by a predetermined distance
Implementation Method 2
a strong interference effect is generated in the light. Accordingly, light of a specific wavelength reflects constructively, and light of remaining wavelengths reflects destructively
Implementation Method 3
The injected electrons and holes are combined to form excitons, and the excitons emit light as discharge energy
Data Source
AI summary
An organic light emitting device including a first pixel, a second pixel, and a third pixel displaying different colors from each other according to the present invention is disclosed, wherein the organic light emitting device includes a substrate, a pixel electrode formed on the substrate, a reflecting electrode facing the pixel electrode, an emission layer disposed between the pixel electrode and the reflecting electrode, and a transflective member forming a micro-cavity along with the reflecting electrode, wherein a optical path length is a distance between the reflecting electrode and the transflective member, and the optical path lengths of at least two pixels among the first pixel, the second pixel, and the third pixel are the same, and the transflective member is removed in the white pixel.