OLED Differential Capping Layer Thickness Optimization
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Solution Overview
Problem
Organic light emitting diode (OLED) displays face challenges in achieving desired color reproducibility and optical efficiency due to uniform thickness of all color pixels, which affects constructive interference and overall light emission characteristics.
Innovation Solution
A differential capping layer with varying thicknesses is introduced, where the thickness of the capping layer differs per color of light emitted, with specific thickness ranges for red, green, and blue light-emitting diodes to optimize constructive interference and enhance optical efficiency and color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform thickness capping layer is used for all color pixels, then the manufacturing process is simple, but color reproducibility and optical efficiency deteriorate
Solution Approach 1:
The patent applies local quality by differentiating the capping layer thickness according to the specific wavelength requirements of each color pixel (red, green, blue). Each color sub-pixel receives a customized thickness value (e.g., 90-120 nm for red, 60-90 nm for green, 60-90 nm for blue) to optimize constructive interference for its specific wavelength range, thereby achieving superior color reproducibility while maintaining a systematic manufacturing approach
2Device complexity
If a uniform thickness capping layer is used for all color pixels, then the device structure is simple, but optical efficiency deteriorates
Solution Approach 1:
The patent optimizes optical efficiency by tailoring the capping layer thickness to match the constructive interference conditions for each color's wavelength. The differential thickness values (90-120 nm for red, 60-90 nm for green, 60-90 nm for blue) are specifically selected to maximize light extraction efficiency for each color, thereby improving overall device optical efficiency without requiring complex multi-layer structures
3Manufacturing precision
If differential thickness capping layers are used for different colors, then color reproducibility and optical efficiency are improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements parameter changes by varying only the thickness parameter of the capping layer across different color pixels while maintaining the same material composition and structural configuration. This approach achieves superior color reproducibility and optical efficiency by optimizing the optical path difference for each wavelength, without introducing additional structural complexity or requiring different materials for different colors
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
The differential capping layer effectively maximizes optical efficiency and color reproducibility by tailoring the thickness of the capping layer to each color, improving the overall performance of the OLED display.
Implementation Method 1
The organic light emitting diode has such an optical characteristic such that the maximum constructive interference occurs at a specific thickness per respective wavelengths of the emitted light
Data Source
AI summary
An organic light emitting diode display includes a substrate main body, a plurality of organic light emitting diodes formed on the substrate main body, and a differential capping layer covering the plurality of organic light emitting diodes, the differential capping layer having a plurality of thicknesses. The differential capping layer has first regions with a thickness of 90 nm to 120 nm, and second regions with a thickness smaller than the thickness of the first regions.