Organic EL Element Reflective Interface Transport Layers
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Solution Overview
Problem
Conventional organic EL elements face challenges in maintaining luminescence balance and efficiency due to complex production processes and increased power consumption, particularly when emitting light with multiple peaks, as they require multiple luminescent layers and complex carrier balance adjustments.
Innovation Solution
An organic EL element with a simple structure is achieved by incorporating a reflecting electrode for either the anode or cathode, and using doped and non-doped layers in the hole transport and electron transport layers, along with a reflection surface at their interface, allowing for efficient light emission with multiple peaks without the need for multiple luminescent layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple luminescent layers are provided to emit light with multiple peaks, then the luminescence efficiency is improved, but the device complexity and production process become complicated
Solution Approach 1:
The patent segments the transport layer into multiple functional sub-layers (hole injection layer, hole transport layer, electron transport layer, electron injection layer) rather than using multiple luminescent layers. This segmentation allows different layers to specialize in charge injection and transport functions, enabling multiple emission peaks through electroluminescence while maintaining a simpler overall structure compared to stacking multiple luminescent layers.
Solution Approach 2:
The transport layers in the patent serve multiple functions: charge injection, charge transport, and optical emission. By designing these layers with multi-functional capabilities, the patent eliminates the need for separate dedicated luminescent layers for each emission peak, thereby reducing structural complexity while maintaining the ability to emit light with multiple peaks.
2Illumination intensity
If multiple luminescent layers are laminated to achieve multiple emission peaks, then the luminescence property is improved, but the manufacturing precision and production margin decrease
Solution Approach 1:
The patent divides the device into distinct functional segments (injection layers, transport layers, luminescent layers) with clear interfaces. This segmentation simplifies the manufacturing process by allowing each layer to be deposited and characterized independently, improving production margin compared to the challenge of precisely aligning and laminating multiple luminescent layers.
Solution Approach 2:
Each layer in the patent is designed with specific local properties optimized for its function (e.g., hole injection layer optimized for hole injection, electron transport layer optimized for electron transport). This local quality optimization allows for better control during manufacturing and easier troubleshooting, improving production precision compared to uniform multi-luminescent layer structures.
3Illumination intensity
If multiple luminescent layers are provided for multiple emission peaks, then the luminescence efficiency is improved, but the power consumption increases
Solution Approach 1:
The transport layers perform multiple functions including charge injection, charge transport, and light emission. This multi-functionality reduces the need for additional dedicated luminescent layers, thereby reducing the total number of layers that require driving voltage and current, which in turn reduces overall power consumption while maintaining multiple emission peaks.
Solution Approach 2:
The patent merges the charge transport function and light emission function into the same layers. By combining these functions rather than separating them into distinct layer types, the patent reduces the total layer count and associated power requirements, achieving multiple emission peaks with lower power consumption compared to conventional multi-luminescent layer approaches.
4Illumination intensity
If the carrier balance is adjusted in multiple luminescent layers to maintain luminescence balance, then the luminescence property is improved, but the device complexity increases
Solution Approach 1:
The patent segments the charge transport functions into separate hole transport and electron transport layers, each optimized for their respective charge carriers. This segmentation allows for independent optimization of hole and electron injection and transport, simplifying carrier balance adjustment compared to the complex inter-layer carrier balance control required in multi-luminescent layer structures.
Solution Approach 2:
Each transport layer is designed with local properties specifically optimized for its charge carrier type (holes or electrons). This local optimization allows for simpler and more effective carrier balance control, as each layer can be independently tuned without the complex interdependencies that arise in multi-luminescent layer configurations.
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 simplifies the production process, improves luminescence properties, and reduces power consumption while maintaining efficient light emission with multiple peaks, enhancing the overall performance and manufacturing ease of organic EL elements.
Implementation Method 1
a reflection surface that reflects light from the luminescent layer is provided at an interface between the doped layer and the non-doped layer
Implementation Method 2
at least one of the hole transport layer and the electron transport layer is composed of a doped layer to which a dopant material is added
Implementation Method 3
organic EL (electroluminescent) element that utilizes electro luminescence of an organic material
Data Source
AI summary
In an organic EL element equipped with an anode, a cathode, a luminescent layer, and an electron transport layer, the cathode includes a reflecting electrode. The electron transport layer includes a doped electron transport layer to which an n-type dopant material is added and a non-doped electron transport layer to which an n-type dopant material is not added. A first reflection surface that reflects light from the luminescent layer is provided at an interface between the doped electron transport layer and the non-doped electron transport layer.