OLED Microcavity for Color Uniformity and Efficiency
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Solution Overview
Problem
Organic light emitting devices (OLEDs) face challenges in achieving uniform color quality due to varying light emission efficiencies across different colored pixels, leading to issues with color coordinates and reduced emission efficiency when combining red, green, and blue colors.
Innovation Solution
Incorporating a semi-transparent member in specific pixels to form a microcavity with electrodes, enhancing the emission efficiency of the white light by selectively amplifying certain wavelengths and reducing others, and using a combination of sub-emitting layers to produce white light with a yellowish tint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different light emitting materials are used for red, green, and blue pixels, then color variety is achieved, but emission efficiency varies across colors leading to poor color quality
Solution Approach 1:
The patent applies local quality by introducing a semitransparent member specifically in pixels with low emission efficiency (blue and white pixels) rather than uniformly across all pixels. This selective application enhances the emission efficiency of specific local regions without affecting other pixels, thereby resolving the contradiction between color variety and uniform emission efficiency.
2Adaptability or versatility
If a color filter layer is added to produce color display from white light, then color display capability is improved, but device complexity increases
Solution Approach 1:
The patent employs color changes by utilizing the optical interference effect of the semitransparent member to selectively enhance specific wavelengths (blue region for blue pixels, yellow region for white pixels). This wavelength-selective enhancement achieves color display capability without requiring additional color filter layers, thereby improving color display while avoiding increased device complexity.
3Ease of operation
If the same voltage is applied to all pixels, then ease of operation is maintained, but color uniformity deteriorates due to different emission efficiencies
Solution Approach 1:
The patent uses copying by creating a microcavity structure that replicates the optical enhancement effect in low-efficiency pixels. The semitransparent member forms a microcavity with the electrode, copying the light-trapping and wavelength-selective emission mechanism that naturally occurs in high-efficiency pixels, thereby achieving color uniformity under uniform voltage control.
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
Improves color purity and emission efficiency by selectively enhancing specific wavelengths, overcoming the limitations of low emission efficiency in certain color layers and achieving a consistent white light output.
Implementation Method 1
a first semitransparent member disposed on the first electrode to form a microcavity with the second electrode
Implementation Method 2
the light emitting member may include a plurality of sub-emitting layers which emit light having different wavelengths, and the light having different wavelengths may be combined to emit a substantially white light
Data Source
AI summary
An organic light emitting device includes a plurality of colored pixels, and a white pixel, wherein the respective pixels include; a first electrode, a second electrode which faces the first electrode, and a light emitting member disposed between the first electrode and the second electrode, and the white pixel further includes; a first semi-transparent member disposed on the first electrode to form a microcavity with the second electrode.