Common Electron Transport Layer for OLED Energy Alignment
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Solution Overview
Problem
Existing organic light emitting devices face challenges in achieving improved driving voltage, efficiency, and lifetime due to the complexity of their multilayered structures and the need for separate electron transport layers for each color emitting layer.
Innovation Solution
The organic light emitting device incorporates a structure with a common electron transport layer adjacent to red, green, and blue light emitting layers, where the energy levels of the electron transport layer materials satisfy specific mathematical expressions to optimize energy level alignment, allowing for improved hole and electron transport and exciton formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate electron transport layers are used for each color emitting layer, then the efficiency of electron transport is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges three separate electron transport layers (one for each color emitting layer) into a single common electron transport layer that serves all three color emitting layers (red, green, and blue). This consolidation reduces the overall number of layers in the device structure while maintaining effective electron transport to each emitting layer through proper energy level alignment, thereby reducing device complexity without sacrificing electron transport efficiency.
Solution Approach 2:
The common electron transport layer performs multiple functions simultaneously: it transports electrons to the red light emitting layer, the green light emitting layer, and the blue light emitting layer. This multi-functional design eliminates the need for separate dedicated electron transport layers for each color, simplifying the overall device structure while maintaining the reliability of electron transport across all emitting layers.
2Manufacturing precision
If multiple separate electron transport layers are used, then the precision of energy level alignment is improved, but the manufacturing process becomes more complex
Solution Approach 1:
By combining multiple separate electron transport layers into one common layer, the patent reduces the number of deposition steps and material interfaces that need to be precisely controlled during manufacturing. The single common electron transport layer can be deposited in one process step, simplifying the manufacturing process while maintaining energy level alignment precision through careful selection of materials with appropriate HOMO and LUMO energy levels that satisfy the specified mathematical relationships with each color emitting layer.
3Ease of manufacture
If a common electron transport layer is used for all color emitting layers, then the manufacturing process is simplified, but the energy level alignment must be precisely controlled
Solution Approach 1:
The patent addresses the energy level alignment challenge by establishing specific mathematical relationships between the HOMO and LUMO energy levels of the common electron transport layer and those of each color emitting layer. By defining these energy level parameters and their relationships (through the mathematical expressions relating EHOMO-ET, ELUMO-ET to the emitting layer energy levels), the patent provides clear design criteria for material selection, enabling precise energy level alignment to be achieved through parameter control rather than complex structural arrangements.
4Device complexity
If the electron transport layer is positioned adjacent to all light emitting layers, then the device structure is simplified, but the driving voltage control becomes more challenging
Solution Approach 1:
The patent applies local quality by allowing the common electron transport layer to have different local interactions with each color emitting layer through the hole transport layer. While the electron transport layer is positioned adjacently to all light emitting layers for structural simplicity, the energy level alignment is optimized locally for each interface (red, green, and blue emitting layers) through the mathematical relationships defined in the patent. This enables proper electron injection and driving voltage control at each local interface while maintaining overall structural simplicity.
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 driving voltage, efficiency, and lifetime of the organic light emitting device by simplifying the manufacturing process and ensuring effective energy level alignment for efficient light emission.
Implementation Method 1
the electrons are injected from the cathode into the organic material layer, and when the injected holes and the electrons meet each other, an exciton is formed
Implementation Method 2
an organic light emitting phenomenon refers to a phenomenon where electric energy is converted into light energy by using an organic material
Implementation Method 3
when the injected holes and the electrons meet each other, an exciton is formed, and light is emitted when the exciton falls to a ground state again
Data Source
AI summary
The present invention relates to an organic light emitting device comprising a light emitting layer and an electron transport layer which satisfy the following mathematical expressions, EHOMO-ET>EHOMO-BH and ELUMO-ET>ELUMO-GH, and having improved driving voltage, efficiency, and lifetime.