White OLED Emission Layers for Color Viewing Angle
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Solution Overview
Problem
Current white organic light emitting devices face challenges in enhancing red, green, and blue emission efficiencies and color reproduction rates due to incomplete energy transfer and limited dopant components, leading to reduced color viewing angles and expression capabilities.
Innovation Solution
A white organic light emitting device with a novel structure featuring at least two emission layers emitting the same color, optimized to have peak wavelengths within specific ranges, and strategically positioned to enhance emission efficiency and color viewing angles by adjusting the spectrum change rate and cavity peak of each emission layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single emission layer with dopants is used to manufacture white OLED, then manufacturing process is simplified, but energy transfer to dopant is incomplete and white light balance cannot be adjusted
Solution Approach 1:
The single emission layer is divided into multiple emission layers (first emission layer with blue dopant, second emission layer with yellow-green dopant, third emission layer with red dopant). Each layer independently optimizes energy transfer to its specific dopant, eliminating the incomplete energy transfer problem of single-layer structures while maintaining manufacturing feasibility through sequential layer deposition
2Device complexity
If dopant components are limited by dopant characteristics, then device structure is simplified, but color balance and white light quality are compromised
Solution Approach 1:
Different dopant components are selectively placed in different emission layers based on their specific characteristics and optimal emission wavelengths. The first emission layer uses blue dopant (480-490nm), second layer uses yellow-green dopant (560-570nm), and third layer uses red dopant (610-620nm). This local optimization of dopant selection in each layer achieves superior color reproduction while managing device complexity through systematic arrangement
3Illumination intensity
If emission layers are stacked to realize white light, then color balance is improved, but peak wavelength range mismatch with color filter transmissive range occurs
Solution Approach 1:
The emission layers are designed with specific peak wavelength parameters that precisely match the transmissive ranges of the color filters. The blue emission layer peaks at 480-490nm, yellow-green at 560-570nm, and red at 610-620nm. These parameter optimizations ensure maximum transmission efficiency through the corresponding color filters while maintaining accurate color balance in the emitted white light
4Illumination intensity
If blue and yellow-green emission layers are provided, then white light emission is achieved, but cavity peak difference causes spectrum change rate variation with viewing angle
Solution Approach 1:
The invention adds a third dimension to the emission layer structure by introducing a red emission layer in addition to the blue and yellow-green layers. This three-layer configuration creates a more balanced optical cavity system where the additional layer compensates for spectrum changes with viewing angle, stabilizing the overall emission spectrum and reducing color shift across different observation angles
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 significantly improves red, green, and blue emission efficiencies, leading to enhanced color reproduction rates and wider color viewing angles, thereby improving the overall panel efficiency and color representation.
Implementation Method 1
An electron and a hole are injected from the two electrodes into the organic emission layer, and an exciton is generated by recombination of the electron with the hole. The organic light emitting device is a device using the principle that light is emitted when the generated exciton is dropped from an excited state to a ground state.
Implementation Method 2
a phosphorescent material contributes a triplet exciton to emit light and thus enables a high-efficiency device to be more easily implemented than that of a fluorescent material
Data Source
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AI summary
Disclosed is a white organic light emitting device (100, 200, 300) for enhancing emission efficiency and a color viewing angle or a color reproduction rate. The white organic light emitting device (100, 200, 300) includes a first emission part (110, 210, 310) between a first electrode (102, 202, 302) and a second electrode (104, 204, 304), the first emission part (110, 210, 310) having a first emission layer (114, 214, 314), a second emission part (120, 220, 320) on the first emission part (110, 210, 310), the second emission part (120, 220, 320) having a second emission layer (124, 224, 324), and a third emission part (130, 230, 330) on the second emission part (120, 220, 320), the third emission part (130, 230, 330) having a third emission layer (134, 234, 334). At least two emission layers (114, 124) of the first to third emission layers (114, 124, 134, 214, 224, 234, 314, 324, 334) emit lights having a same color to enhance emission efficiency and a color viewing angle, and the at least two emission layers (114, 124, 214, 224, 314, 324) are adjacent to each other.