OLED Emission Layer Structure for Stable Recombination Zones
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Solution Overview
Problem
The recombination zone in organic light emitting diodes (OLEDs) moves away from the emission layer due to temperature changes, leading to reduced light emission and accelerated degradation, thereby shortening the lifetime of the display device.
Innovation Solution
The thickness of the emission layer is equal to or greater than that of the organic layers, with specific configurations of hole and electron transfer layers, ensuring the recombination zone remains within the emission layer even at varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the emission layer thickness is increased to maintain recombination zone within emission layer at high temperature, then the lifetime and efficiency are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies parameter changes by adjusting the thickness of the emission layer and organic layers to specific ranges (emission layer: 50-200 nm, organic layers: 20-80 nm each) to ensure the recombination zone remains within the emission layer at high temperatures, thereby improving device lifetime and efficiency without excessive complexity
Solution Approach 2:
The patent addresses the dynamic shift of the recombination zone with temperature changes by designing a layered structure where the emission layer thickness is specifically optimized to accommodate the movement of the recombination zone from the center toward the adjacent organic layer at elevated temperatures, maintaining effective light emission across temperature ranges
2Productivity
If the emission layer thickness is increased to prevent recombination zone migration, then light emission efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise thickness parameters for the emission layer (50-200 nm) and organic layers (20-80 nm each) to optimize light emission efficiency while providing clear manufacturing guidelines that balance performance requirements with fabrication capabilities
Solution Approach 2:
The patent employs partial action by configuring the emission layer thickness to be equal to or greater than the organic layer thickness, which is sufficient to maintain the recombination zone within the emission layer under normal operating conditions without requiring excessive thickness that would complicate manufacturing
3Duration of action of stationary object
If the organic layer thickness is decreased to maintain recombination zone in emission layer, then the lifetime is improved, but the device stability at high temperature may be compromised
Solution Approach 1:
The patent optimizes the thickness parameters of both emission layer (50-200 nm) and organic layers (20-80 nm) to achieve a balance where the recombination zone remains within the emission layer at high temperatures, improving lifetime while maintaining device stability through appropriate thickness ratios
Solution Approach 2:
The patent accounts for thermal dynamics by designing the layered structure to accommodate the temperature-induced migration of the recombination zone, ensuring that even at elevated temperatures, the recombination zone remains within the emission layer, thus maintaining both lifetime and stability
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 efficiency and extends the lifetime of the OLEDs by maintaining effective light emission and reducing thermal transition of light energy, thus improving performance under room and high temperature conditions.
Implementation Method 1
An electron and a hole are injected from the two electrodes into the emission layer, and an exciton is generated by combining the electron with the hole. The OLEDs are devices based on the principle that light is emitted when the generated exciton is dropped from an excited state to a ground state.
Data Source
AI summary
Disclosed are an organic light emitting display device and lighting apparatus for vehicles using the same. The organic light emitting display device includes a first layer including a first organic layer and a first emission layer on a first electrode, a second layer including a second emission layer and a second organic layer on the first layer, a second electrode on the second layer, and a third organic layer between the first layer and the second layer. A thickness of the first emission layer is equal to or greater than a thickness of each of the first organic layer and the second organic layer.