OLED Anode Thickness Variation for Color Uniformity
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Solution Overview
Problem
Conventional white OLEDs suffer from degraded color uniformity due to the inclusion of blue emitting material layers, leading to inefficient blue light emission and mismatched luminance curves with red and green light, resulting in insufficient brightness and color gamut issues.
Innovation Solution
The organic light emitting device incorporates a three-stack structure with distinct anode thicknesses in red, green, and blue pixel regions, where the anode in the blue pixel region has a thickness of 500 to 600 Å, and in the green pixel region, it is ⅖ to ⅔ of the blue anode thickness, optimizing the constructive interference for improved blue light efficiency and matching luminance curves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a blue EML is included in the first and third emitting parts of a white OLED, then the device can emit white light, but color uniformity is degraded
Solution Approach 1:
The patent applies local quality by making the anode thickness position-dependent: the anode has a first thickness in the blue pixel region and a second thickness (2/5 to 2/3 of the first thickness) in the green pixel region. This localized structural variation optimizes light extraction and interference effects specifically in the green region to compensate for the color uniformity degradation caused by blue EML inclusion.
2Use of energy by moving object
If the anode thickness is increased to improve blue light emission efficiency, then blue emitting performance improves, but green light emission becomes insufficient
Solution Approach 1:
The patent implements local quality by differentiating anode thickness across different pixel regions. The anode has a greater thickness in the blue pixel region to enhance blue light emission efficiency, while having a reduced thickness (2/5 to 2/3) in the green pixel region to improve green light extraction and brightness, thereby resolving the trade-off between blue and green emission performance.
Solution Approach 2:
The patent introduces a new dimension of control by varying the anode thickness parameter spatially across different pixel regions rather than using a uniform thickness. This dimensional variation in the anode structure enables independent optimization of light emission characteristics for different colors within the same device.
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 emitting efficiency of blue color, improves color uniformity, and increases the overlapping ratio in the color range standard BT 2020, providing high emitting efficiency and desired color gamut.
Implementation Method 1
optimizing the constructive interference for improved blue light efficiency and matching luminance curves
Data Source
AI summary
Discussed is an organic light emitting device including a substrate. The substrate can include red, green and blue pixel regions, and an organic light emitting diode including an anode, a cathode over the anode and an organic emitting layer between the anode and the cathode and corresponding to the red, green and blue pixel regions. The organic emitting layer includes a first emitting part including a red emitting material layer, a second emitting part including a green emitting material layer and positioned between the first emitting part and the cathode and a third emitting part including a blue emitting material layer and positioned between the second emitting part and the cathode. The anode in the blue pixel region has a first thickness, and the anode in the green pixel region has a second thickness being approximately ⅖ to ⅔ of the first thickness.