OLED Micro-Cavity Optimization via Asymmetric Stack Thickness
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Solution Overview
Problem
Current organic light-emitting display (OLED) apparatuses face challenges in achieving high emission efficiency and color reproduction ratio while minimizing color change rate, particularly in optimizing the micro-cavity structure between electrodes.
Innovation Solution
A top emission type OLED apparatus is designed with a specific thickness ratio in the stacks between the reflection-anode and transparent cathode, where the thickness of the stack closer to the cathode is larger than that closer to the anode, optimizing the micro-cavity for improved light-emission efficiency and color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the thickness of stacks between electrodes is uniformly distributed, then the device structure is simple and easy to manufacture, but the emission efficiency and color reproduction ratio are insufficient
Solution Approach 1:
The patent applies local quality by varying the thickness of different stacks in the light-emitting unit. Specifically, the first stack has a different thickness than the second stack, with each stack's thickness optimized for its specific position and function. This local differentiation allows each stack to contribute optimally to light emission, improving overall emission efficiency while maintaining manufacturability through a systematic thickness design rather than complete uniformity.
Solution Approach 2:
The patent implements parameter changes by optimizing the thickness parameter of each stack. The first stack thickness is set to satisfy a specific mathematical relationship with the emission wavelength, and the second stack thickness is similarly optimized. This parameter optimization resolves the contradiction by achieving high emission efficiency through calculated thickness values while maintaining a relatively simple structural configuration.
2Loss of energy
If the micro-cavity structure is optimized for high emission efficiency, then the color reproduction ratio improves, but the color change rate increases with viewing angle
Solution Approach 1:
The patent addresses color consistency by assigning different thicknesses to different stacks based on their specific positions and emission characteristics. The first stack, closer to the anode, has a thickness optimized for its location, while the second stack, closer to the cathode, has a different thickness. This local optimization ensures that each stack contributes to color stability in its specific region, reducing overall color change with viewing angle while maintaining high emission efficiency.
3Measurement precision
If the stack thickness is increased to improve color reproduction ratio, then the emission efficiency improves, but the device complexity increases
Solution Approach 1:
The patent resolves the contradiction between color reproduction ratio and device complexity by optimizing the thickness parameter of existing stacks rather than adding more stacks or layers. The first and second stacks have their thicknesses carefully calculated based on emission wavelength and position, achieving high color reproduction ratio (99% or more) and emission efficiency without increasing the number of structural elements. This parameter optimization approach maintains relatively simple device structure while achieving superior performance.
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 design enhances light-emission efficiency, achieves a color reproduction ratio of 99% or more, and reduces color change rate within a 0° to 60° viewing angle, providing clear and realistic images suitable for large-sized displays.
Implementation Method 1
the OLED apparatus is a display apparatus of displaying an image by producing exciton through a recombination of hole and electron, which are injected from anode and cathode, in a light emitting layer, and generating light with a specific wavelength by an energy emission of the produced exciton
Implementation Method 2
a top emission type organic light emitting display apparatus (OLED apparatus) which is capable of realizing high emission efficiency, good color reproduction ratio, and improved color change rate by optimizing a thickness ratio in a plurality of stacks between two electrodes
Data Source
Figure 1
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Figure 3~4A
AI summary
Disclosed is an OLED apparatus (1000, 2000) that may include a reflection-anode (410, 1410), a transparent cathode (600, 1600), and a plurality of stacks (510, 520, 530, 1510, 1520) between the reflection-anode and the transparent cathode (600, 1600), wherein, among the plurality of stacks (510, 520, 530, 1510, 1520), a thickness of the stack (530, 1520) disposed relatively close to the transparent cathode (600, 1600) is larger than a thickness of the stack (510, 1510) disposed relatively close to the reflection-anode (410, 1410) so that it is possible to optimize a micro-cavity of light emitted from the plurality of stacks (510, 520, 530, 1510, 1520), thereby improving a light-emission efficiency and a color reproduction ratio and reducing a color change rate in accordance with a viewing angle.