OLED Red-Yellow-Green Emitter Layer Segmentation
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Solution Overview
Problem
In organic light emitting diode (OLED) display devices, the red emitting material layer's thickness and doping concentration affect the white color coordinate and efficiency ratios, leading to increased deterioration speed and decreased lifetime, as well as higher driving voltage.
Innovation Solution
An OLED display device with a red-yellow-green emitting material layer incorporating a yellow-green host, yellow-green dopant, and red dopant, which emits a red colored light, maintaining proper white color coordinates and efficiency ratios, while reducing deterioration speed and driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the red emitting material layer has a relatively great thickness and a relatively high doping concentration, then the red light emission intensity is improved, but the green efficiency ratio and white color coordinate deviate from target values and the color temperature decreases
Solution Approach 1:
The patent divides the red emitting material layer into multiple sub-layers with different thicknesses and doping concentrations. The first sub-layer has greater thickness and higher doping concentration for strong red emission, while the second sub-layer has smaller thickness and lower doping concentration to maintain color balance, thus resolving the contradiction between red emission intensity and white color coordinate precision
Solution Approach 2:
Different regions of the red emitting material layer are assigned different properties: the first sub-layer (closer to the electron injecting electrode) has higher doping concentration and greater thickness for intense red emission, while the second sub-layer has lower doping concentration and smaller thickness for color balance, achieving local optimization of both emission intensity and color precision
2Illumination intensity
If the red emitting material layer has a relatively great thickness and a relatively high doping concentration, then the red light emission intensity is improved, but the deterioration speed increases and the lifetime decreases
Solution Approach 1:
The red emitting material layer is segmented into multiple sub-layers where the first sub-layer has higher doping concentration and greater thickness for strong red emission, while the second sub-layer has lower doping concentration and smaller thickness that deteriorates slower, thus extending the overall device lifetime while maintaining red emission intensity
Solution Approach 2:
The second sub-layer is designed with lower doping concentration and smaller thickness as a sacrificial layer that deteriorates slower than the first sub-layer, effectively extending the device lifetime. This layer can be replaced or is designed to last longer, allowing the first sub-layer to maintain high red emission intensity without compromising overall device reliability
3Illumination intensity
If the red emitting material layer has a relatively great thickness and a relatively high doping concentration, then the red light emission intensity is improved, but the driving voltage increases
Solution Approach 1:
The red emitting material layer is divided into multiple sub-layers with different doping concentrations and thicknesses. The first sub-layer has higher doping concentration and greater thickness for strong red emission, while the second sub-layer has lower doping concentration and smaller thickness that requires less driving voltage, thus reducing the overall driving voltage while maintaining red light emission intensity
Solution Approach 2:
Different regions of the red emitting material layer are optimized locally: the first sub-layer has higher doping concentration and greater thickness for intense red emission, while the second sub-layer has lower doping concentration and smaller thickness for reduced voltage requirement, achieving local balance between emission intensity and power consumption
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 increases the lifetime of the OLED display device and decreases the driving voltage by optimizing the red-yellow-green emitting material layer's composition and thickness, ensuring stable red, green, and blue efficiency ratios.
Implementation Method 1
charges are injected into a light emitting layer between a cathode of an electron injecting electrode and an anode of a hole injecting electrode to form an exciton, and the exciton transitions from an excited state to a ground state to emit a light
Implementation Method 2
a red-yellow-green emitting material layer including a yellow-green host, a yellow-green dopant and a red dopant
Data Source
AI summary
Organic light emitting diode display devices are provided. In at least one embodiment, an organic light emitting diode display device includes a first electrode; a first stack on the first electrode and the first stack is configured to emit a blue colored light; a first charge generating layer on the first stack; a second stack on the first charge generating layer and the second stack is configured to emit a red colored light and a yellow-green colored light; and a second electrode on the second stack. The second stack includes: a red-yellow-green emitting material layer including a yellow-green host, a yellow-green dopant and a red dopant; and a yellow-green emitting material layer including the yellow-green host and the yellow-green dopant.