Two-Stack OLED Structure With Shared Blue Layers for High Luminance
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Solution Overview
Problem
Existing organic light emitting diode (OLED) display devices for vehicles face challenges in achieving high luminance while simplifying the manufacturing process and reducing material costs, particularly under varying light conditions, and struggle to maintain low voltage characteristics due to increased complexity and number of organic layers.
Innovation Solution
The OLED structure incorporates a two-stack design with shared blue light emitting layers throughout the active area, omitting separate electron transport layers and using hosts with specific LUMO energy level differences to enhance electron transport and excitation, reducing the need for high-definition deposition masks and expensive dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of organic layers is increased to achieve high efficiency, then luminance efficiency is improved, but driving voltage increases and device complexity increases
Solution Approach 1:
The patent merges the electron transport function into the blue light emitting layer by incorporating electron transporting materials (ETM) as hosts or dopants in the blue emission layer. This eliminates the need for separate electron transport layers, reducing the total number of organic layers while maintaining efficient electron transport and high luminance efficiency.
Solution Approach 2:
The blue light emitting layer is designed to perform multiple functions simultaneously: it emits blue light and also serves as the electron transport layer. The host materials in the blue emission layer (such as BCP, Bpy-OXD, or Bpy-OXD-Au complexes) provide both exciton generation for blue emission and electron transport pathways, making the layer universal in function.
2Reliability
If separate electron transport layers are provided for each stack, then electron transport efficiency is improved, but manufacturing complexity and material costs increase
Solution Approach 1:
The patent combines the electron transport function with the blue light emitting layer, eliminating the need for separate electron transport layers in each stack. The blue emission layer contains electron transporting materials that facilitate efficient electron transport from the charge generation layer to the red and green light emitting layers, simplifying the manufacturing process while maintaining electron transport efficiency.
Solution Approach 2:
The blue light emitting layer serves as a universal electron transport pathway for both stacks (red and green subpixels). The electron transporting hosts or dopants in the blue layer provide a common electron supply route to both red and green emission regions, reducing the number of separate electron transport layers needed and simplifying deposition processes.
3Manufacturing precision
If high-definition deposition masks are used for precise layer deposition, then manufacturing precision is improved, but material costs and process complexity increase
Solution Approach 1:
The blue light emitting layer is deposited as a single universal layer that serves both stacks (red and green subpixels) and provides electron transport function. This eliminates the need for complex high-definition masks to define separate electron transport regions, as the blue layer naturally spans the entire active area and functions for both pixel types through its electron transporting properties.
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 results in improved luminance, reduced material costs, and lower driving voltage, while maintaining high efficiency and stability of color emission, even under external light conditions, by integrating blue light emitting layers for electron transport and excitation across the entire active area.
Implementation Method 1
a first blue light emitting layer and a second blue light emitting layer which include a first host which generates excitons, a second host having an electron transporting property, and a blue dopant
Implementation Method 2
a second host having an electron transporting property
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~5A
AI summary
Disclosed are an organic light emitting diode, an organic light emitting diode display device and a display device for vehicles using the same. The organic light emitting diode may achieve process simplification and reduction in material costs while maintaining high luminance, through structure change.