OLED Pixel Structure for Balanced Color and Efficiency
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Solution Overview
Problem
Current organic light emitting devices face challenges in achieving balanced luminance and color reproducibility across red, green, and blue pixels due to differences in hole mobility and emission layer structures, which affect emission efficiency and color purity.
Innovation Solution
The implementation of a pixel group structure with a transflective electrode and transparent supplementary members, where each pixel has a specific organic emission layer with controlled hole mobility and host materials, and the use of a common electrode to enhance optical path lengths and refractive indices for each color, allowing for improved color balance and emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If different organic emission layers are used for red, green, and blue pixels, then color purity is improved, but manufacturing complexity increases due to multiple deposition processes
Solution Approach 1:
The patent divides the emission layer into multiple functional sub-layers: a first organic emission layer for color emission and a second organic emission layer for hole transport. This segmentation allows each layer to be optimized independently for its specific function, achieving color purity through the first layer while simplifying manufacturing by using the second layer as a common hole transport layer across all pixels.
Solution Approach 2:
The second organic emission layer serves multiple functions: it acts as a hole transport layer for all red, green, and blue pixels simultaneously, and provides a common structural basis for depositing different color-emitting first layers. This multi-functionality reduces manufacturing complexity by eliminating the need for separate hole transport layers for each color.
2Productivity
If hole mobility is increased in emission layers, then emission efficiency is improved, but color balance deteriorates due to excessive hole injection affecting relative luminance
Solution Approach 1:
The patent creates different hole mobility characteristics in different regions/layers: the first organic emission layer has lower hole mobility to control hole injection and maintain color balance, while the second organic emission layer has higher hole mobility to ensure efficient hole transport. This local differentiation of hole mobility allows simultaneous optimization of color balance and emission efficiency.
Solution Approach 2:
The patent changes the hole mobility parameter between the two organic emission layers. The first layer uses materials with lower hole mobility (10^-6 to 10^-4 cm²/Vs) to regulate hole injection, while the second layer uses materials with higher hole mobility (10^-5 to 10^-3 cm²/Vs) for efficient transport. This parameter change strategy resolves the contradiction between emission efficiency and color balance.
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 configuration enhances the intensity and purity of primary colors, improving the overall optical efficiency and color reproducibility of the organic light emitting device by optimizing the optical path lengths and refractive indices for each pixel.
Implementation Method 1
One of the two electrodes injects holes and the other injects electrons into the light emitting layer. The injected electrons and holes are combined to form excitons and the excitons emit light as discharge energy.
Implementation Method 2
Each of the first pixel, second pixel, and third pixel includes a pixel electrode having a transflective electrode, an organic emission layer on the pixel electrode that displays the first color and a common electrode on the organic emission layer.
Data Source
AI summary
An organic light emitting device and a manufacturing method thereof is provided. The organic light emitting device includes a first pixel that displays a first color, a second pixel that displays a second color, and a third pixel that displays a third color. The first pixel, the second pixel and the third pixel together form one pixel. Each of the first pixel, second pixel, and third pixel includes a pixel electrode having a transflective electrode, an organic emission layer on the pixel electrode that displays the first color, a common electrode on the third color organic emission layer, and a transparent supplementary member between the pixel electrode and the common electrode.