OLED Microcavity Enhancing Color Purity
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Solution Overview
Problem
OLED displays face limitations in achieving high color reproducibility due to the limitations in color reproducibility of color filters used in existing technologies, making it difficult to achieve the high color reproducibility required by standards like NTSC.
Innovation Solution
The OLED display incorporates a microcavity structure in the green pixel, using a translucent conductive layer and adjusting the thickness of transparent conductive layers to enhance light of a narrow wavelength region and suppress other wavelengths, thereby improving color purity and reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If color filters are used to express red, green and blue colors by pixel, then the display can show full color spectrum, but the color reproducibility is limited by the color filters themselves and cannot achieve high color reproducibility required by NTSC
Solution Approach 1:
The patent applies color changes by using a microcavity structure that selectively enhances specific wavelengths of light through optical resonance. The microcavity acts as a wavelength-selective reflector, creating constructive interference for desired wavelengths and destructive interference for others, thereby changing the spectral composition of emitted light to achieve superior color reproducibility without relying on traditional color filters
Solution Approach 2:
The patent employs parameter changes by adjusting the optical path length within the microcavity structure. By controlling the thickness of the microcavity layer and the refractive index of materials, the resonance wavelength is precisely tuned to enhance specific color wavelengths. This parameter optimization enables the display to achieve NTSC color reproducibility standards while maintaining full color spectrum coverage
2Manufacturing precision
If fine shadow mask is used to deposit emission layers pixel-by-pixel, then each pixel can have precise color emission, but the method has limitations when display device size is increased
Solution Approach 1:
The patent applies segmentation by dividing the display into pixel regions defined by insulating members rather than using physical masks during deposition. The emission layer is deposited uniformly across the entire display area, and the segmentation function is achieved through the insulating structures that electrically isolate adjacent pixels, enabling scalable manufacturing for large displays while maintaining pixel-level precision
Solution Approach 2:
The patent employs universality by using insulating members that serve multiple functions: they define pixel boundaries, provide electrical insulation between adjacent pixels, and act as structural support for the emission layer. This multi-functional approach eliminates the need for complex shadow masks while maintaining manufacturing precision across displays of various sizes
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 significantly enhances color purity and reproducibility, achieving nearly 100% NTSC color reproducibility, surpassing the 72% achieved without microcavities, and improves light efficiency by amplifying light in a specific wavelength range.
Implementation Method 1
The intermediate first electrode is formed on the lower first electrode and includes a translucent conductor which forms microcavities with the second electrode
Implementation Method 2
using a translucent conductive layer and adjusting the thickness of transparent conductive layers to enhance light of a narrow wavelength region and suppress other wavelengths
Data Source
AI summary
A method for manufacturing an organic light emitting diode (“OLED”) display which includes first and second pixels each displaying a different color, the method includes: sequentially depositing a first transparent conductive layer and a translucent conductive layer; forming an intermediate first electrode on the second pixel by photolithography and etching of the translucent conductive layer; depositing a second transparent conductive layer on the intermediate first electrode and the first transparent conductive layer; forming a first electrode of the first pixel which includes upper and lower layers on the first pixel and a first electrode of the second pixel which includes a lower first electrode, an intermediate first electrode, and an upper first electrode by photolithography and etching of the second transparent conductive layer and the first transparent conductive layer; forming an emission layer on the first electrodes of the first and second pixels; and forming a second electrode on the emission layer.