OLED Aperture Ratio via Segmented Emission Layers
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Solution Overview
Problem
Existing organic light emitting devices (OLEDs) face limitations in aperture ratio, driving voltage, emitting efficiency, and lifespan, particularly in achieving high aperture ratios and efficient light emission while maintaining low driving voltage and extended lifespan.
Innovation Solution
The organic light emitting device incorporates a novel structure with multiple emitting layers, including a first emitting part, a second emitting part, and a third emitting part, each with specific material layers and charge generation layers, optimized thicknesses, and dopants to enhance light emission and reduce driving voltage, along with a p-type and n-type host material configuration in the green emitting material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a normal-structure OLED with anode, organic light emitting layer, and cathode is used, then the device can emit light, but the aperture ratio is decreased due to requiring at least three thin film transistors and one storage capacitor
Solution Approach 1:
The organic light emitting layer is segmented into three distinct emitting parts (first, second, and third emitting parts) with different emitting materials, allowing each part to contribute to different color emissions and improving overall device efficiency while reducing the need for additional control components
Solution Approach 2:
The inverted structure integrates multiple functions into the organic light emitting layer itself, which now serves both as the light emission medium and as the structure that defines color output through its three emitting parts, reducing dependency on separate control components
2Reliability
If the organic light emitting layer uses simple emitting materials, then the device structure is simpler, but the emitting efficiency and lifespan are reduced
Solution Approach 1:
Different emitting materials are assigned to different regions of the organic light emitting layer (first, second, and third emitting parts), with each region having optimized material properties for its specific function, thereby improving overall device reliability and emitting efficiency through localized material optimization
Solution Approach 2:
The organic light emitting layer uses composite material structures with multiple emitting materials (including red, green, and blue emitting materials) distributed across three emitting parts, creating a composite system that achieves superior emitting efficiency and lifespan compared to simple single-material structures
3Illumination intensity
If the organic light emitting layer thickness is increased to improve light emission, then the emitting efficiency improves, but the driving voltage increases
Solution Approach 1:
The patent optimizes the thickness parameters of each emitting part within specific ranges (first emitting part: 750-850 Å, second emitting part: 300-400 Å, third emitting part: 50-150 Å) to achieve the optimal balance between light emission intensity and driving voltage, demonstrating parameter optimization to resolve the contradiction
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 significantly improves the aperture ratio, emitting efficiency, and lifespan of the OLED while reducing driving voltage, as demonstrated by the measured emission properties and efficiency metrics.
Implementation Method 1
When electrons from the cathode and holes from the anode are provided into the emitting material layer, the electrons and holes are combined to generate an exciton, and the exciton is transformed from an excited state to a ground state. As a result, the light is emitted from the OLED.
Data Source
AI summary
An organic light emitting device is disclosed, which comprises: a substrate; a cathode over the substrate; an anode disposed over the cathode; and an organic light emitting layer comprising a first emitting part, a second emitting part between the first emitting part and the anode and a third emitting part between the first and second emitting parts and positioned between the cathode and the anode, wherein the first emitting part comprises a first emitting material layer, and the second emitting part comprises a second emitting material layer, wherein the third emitting part comprises a third emitting material layer, and the third emitting material layer comprises a red emitting material layer and a green emitting material layer, wherein the green emitting material layer comprises a first p-type host, a first n-type host and a green dopant.