Tandem Organic Light Emitting Device with Segmented Emission Parts
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Solution Overview
Problem
Existing white organic light emitting devices face challenges in achieving high color reproduction range and emitting efficiency due to differences in peak wavelengths and transmission rates of light emitting layers, particularly when using blue and yellow emitting layers, which result in low color reproduction and efficiency when filtered through color filters.
Innovation Solution
An organic light emitting device structure comprising three emitting parts with multiple emitting layers, including blue, yellow-green, and red layers, optimized to achieve white light emission with three peak wavelengths, enhancing color reproduction and efficiency by adjusting the position and combination of emitting layers within the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a blue emitting layer and a yellow emitting layer are deposited to emit white light, then white light emission is achieved, but color reproduction range and emitting efficiency are reduced due to differences in peak wavelengths and transmission rates through color filters
Solution Approach 1:
The device divides the white light emission function into three separate emitting parts (first, second, and third emitting parts), each containing specific emitting layers. The first and third emitting parts contain blue emitting layers, while the second emitting part contains emitting layers for wavelengths longer than blue. This segmentation allows each part to contribute to different aspects of white light emission, improving overall color reproduction and efficiency.
Solution Approach 2:
The patent introduces a tandem structure with multiple emitting parts stacked in series between the electrodes, adding a dimensional aspect to the emitting layer configuration. This multi-layered arrangement with charge generating layers between emitting parts enables better control over light emission characteristics and color reproduction across different wavelength regions.
2Illumination intensity
If a blue emitting layer and a yellow emitting layer are deposited to emit white light, then white light emission is achieved, but emitting efficiency is reduced due to differences in peak wavelengths and transmission rates through color filters
Solution Approach 1:
The device divides the white light emission function into three separate emitting parts (first, second, and third emitting parts), each containing specific emitting layers. The first and third emitting parts contain blue emitting layers, while the second emitting part contains emitting layers for wavelengths longer than blue. This segmentation allows each part to contribute to different aspects of white light emission, improving overall color reproduction and efficiency.
Solution Approach 2:
The tandem structure with multiple emitting parts arranged in series ensures continuous light emission across different wavelength regions. The charge generating layers between emitting parts maintain continuous charge carrier supply, enabling sustained efficient emission from all layers simultaneously, reducing energy loss and improving overall emitting efficiency.
3Reliability
If multiple emitting layers with different peak wavelengths are used, then color reproduction range is improved, but device complexity increases due to the need for charge generating layers and optimized layer arrangement
Solution Approach 1:
The device divides the white light emission function into three separate emitting parts (first, second, and third emitting parts), each containing specific emitting layers. The first and third emitting parts contain blue emitting layers, while the second emitting part contains emitting layers for wavelengths longer than blue. This segmentation allows each part to contribute to different aspects of white light emission, improving overall color reproduction and efficiency.
Solution Approach 2:
Charge generating layers are introduced as intermediary components between the emitting parts. These charge generating layers facilitate charge carrier generation and transport between the emitting parts, enabling the complex multi-layer structure to function efficiently without requiring separate charge injection mechanisms for each layer, thus managing device complexity.
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
The solution improves color reproduction range and purity, as well as emitting efficiency, by optimizing the layer structure to ensure high color fidelity and luminance, particularly when white light passes through color filters.
Implementation Method 1
When the electron generated in the cathode and the hole generated in the anode are injected into the light emitting layer, an exciton is produced by the electron and hole bond. Then, when the exciton falls to a ground state from an excited state, the organic light emitting device emits light.
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(d)
AI summary
Disclosed is an organic light emitting device that may include first and second electrodes (10, 20); a first emitting part (100) including a first emitting layer (150), the first emitting part (100) provided between the first and second electrodes (10, 20), and the first emitting layer (150) having at least two emitting layers (151, 153, 155) including a blue color emitting layer (151); a second emitting part (200) including a second emitting layer (250), the second emitting part (200) provided between the first emitting part (100) and the second electrode (20), and the second emitting layer (250) having at least two emitting layers (253, 255, 257) including an emitting layer (253, 255, 257) for emitting light having wavelength longer than that of the blue color emitting layer (151); and a third emitting part (300) including a third emitting layer (350), the third emitting part (300) provided between the second emitting part (200) and the second electrode (20), and the third emitting layer (350) having at least two emitting layers (351, 353, 355) including a blue color emitting layer (351).