OLED Electron Transporting Layer Thickness Optimization
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Solution Overview
Problem
Conventional full color organic electroluminescence display devices face challenges in achieving high luminous efficiency and pure color due to differences in luminous efficiency between red, green, and blue colors, and the difficulty in forming fine patterns of organic thin films, particularly with the electron transporting layer affecting blue color purity.
Innovation Solution
The electron transporting layer is formed with a first thickness in the red and green emission regions and a second, different thickness in the blue emission region, optimizing the layer's thickness to enhance chromaticity coordinates and luminous efficiency for each color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common electron transporting layer is formed with uniform thickness across all color regions, then the manufacturing process is simplified, but the luminous efficiency and color purity of red and green emission layers deteriorate
Solution Approach 1:
The electron transporting layer is designed with different thicknesses in different color regions: a first thickness in red and green emission layer regions and a second thickness (different from the first) in blue emission layer regions. This local differentiation optimizes luminous efficiency and color purity for each color while maintaining a relatively simple manufacturing process.
2Manufacturing precision
If the electron transporting layer thickness is optimized for blue color purity, then blue chromaticity is improved, but red and green luminous efficiency deteriorates
Solution Approach 1:
Different thicknesses of the electron transporting layer are applied to different color regions to simultaneously optimize chromaticity coordinates and luminous efficiency for each color. The first thickness in red and green regions and the second thickness in blue regions allow each color to achieve its optimal performance.
Solution Approach 2:
The thickness parameter of the electron transporting layer is varied across different regions to optimize the performance of each color emission layer. By changing this physical parameter locally, the patent achieves both high chromaticity purity and luminous efficiency simultaneously.
3Manufacturing precision
If separate electron transporting layers are formed for each color region, then color purity is maximized, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of forming completely separate electron transporting layers for each color, the patent uses a single continuous layer with locally differentiated thickness. This approach maintains color purity through thickness optimization while avoiding the complexity of multiple separate layers and their associated manufacturing challenges.
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 improves the luminous efficiency of red and green colors while maintaining the same chromaticity coordinates, addressing the limitations of conventional devices by allowing for high-purity color representation.
Implementation Method 1
an electron transporting layer, which is applied to organic layers as a common layer, is formed with a first thickness in the red and green emission layer regions and with a second thickness, which is different from the first thickness, in the blue emission layer region
Implementation Method 2
an organic electroluminescence display device realizes colors based on the principle that holes and electrons, which are injected from an anode and a cathode, are recombined in an emission layer to emit light
Data Source
AI summary
Disclosed is a full color organic electroluminescence display device, comprising a substrate; a first electrode; organic film layers including red, green and blue emission layers and an electron transporting layer; and a second electrode. The thickness of the electron transporting layer, which is preferably formed as a common layer, is different in the red and green emission regions from that in the blue emission region so that the device has an excellent purity of color and improved luminous efficiency of red and green colors.