Organic Electroluminescent Device with Optimized Polymer Layers
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Solution Overview
Problem
Existing organic electroluminescent devices using laminated polymer materials suffer from insufficient light emission efficiency and high driving voltage, particularly in devices with polyphenylene vinylene and alkoxy-substituted polyphenylene vinylene, as well as those with specific hole and electron transporting layers.
Innovation Solution
An organic electroluminescent device is designed with an anode and cathode, featuring a first organic layer with a hole transporting polymer compound and a second organic layer with an electron transporting polymer compound, where the compounds' ionization potentials and work functions satisfy specific criteria, and a light emitting material is included to achieve efficient light emission within a defined color range, optimized by insolubilizing the first layer and forming the second layer in contact with it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If polymer materials are used for organic electroluminescent devices, then multi color light emission and low voltage driving are achieved, but light emission efficiency is insufficient
Solution Approach 1:
The device is divided into multiple organic layers with distinct functions: a first organic layer containing hole transporting polymer compound, a second organic layer containing electron transporting polymer compound, and a light emitting material layer. This segmentation allows each layer to be optimized for its specific function, improving overall light emission efficiency while maintaining multi-color capability through material selection.
Solution Approach 2:
Different regions of the device use different polymer materials with specific properties: the hole transporting layer uses materials with appropriate ionization potentials, the electron transporting layer uses materials with specific electron affinities, and the light emitting layer uses dopant materials. This local optimization of material properties resolves the contradiction between efficiency and manufacturability.
2Reliability
If specific hole and electron transporting polymer layers are laminated, then device structure is formed, but driving voltage is high
Solution Approach 1:
The patent specifies precise parameter ranges for the polymer materials: ionization potential of the hole transporting polymer (Ip1) should satisfy Ip1-Wa≤0.5 eV, electron affinity of the electron transporting polymer (Ea2) should satisfy Wc-Ea2≤0.5 eV, and the energy level difference should satisfy |Ip3-Ip1|≤0.5 eV and |Ea2-Ea3|≤1.0 eV. These parameter optimizations enable lower driving voltage while maintaining structural stability.
Solution Approach 2:
The hole transporting polymer and electron transporting polymer act as intermediary layers that facilitate efficient charge injection and transport between the electrodes and light emitting material. By optimizing their energy levels to match the electrodes and light emitting material, they reduce energy barriers and lower the required driving voltage.
3Illumination intensity
If polymer materials with specific energy levels are used, then light emission efficiency improves, but material selection and manufacturing complexity increases
Solution Approach 1:
The patent establishes clear parameter specifications for material selection: ionization potential difference ≤0.5 eV between hole transporting polymer and light emitting material, electron affinity difference ≤1.0 eV between electron transporting polymer and light emitting material, and specific relationships with electrode work functions. These quantified criteria simplify the material selection process while ensuring high light emission efficiency.
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 device exhibits improved light emission efficiency and reduced driving voltage, achieving balanced performance with diverse emission colors, suitable for applications in sheet light sources and displays.
Implementation Method 1
a first organic layer arranged in contact with or adjacent to the anode between the electrodes and containing a hole transporting polymer compound
Implementation Method 2
a second organic layer arranged in contact with the first organic layer between the first organic layer and the cathode and containing an electron transporting polymer compound
Implementation Method 3
at least one of the first organic layer and the second organic layer contains a light emitting material... and light is emitted from the first organic layer or from the first organic layer and the second organic layer
Data Source
AI summary
An organic electroluminescent device excellent in light emission efficiency and driving voltage, having electrodes composed of an anode and a cathode, a first organic layer arranged in contact with or adjacent to the anode between the electrodes and containing a hole transporting polymer compound and a second organic layer arranged in contact with the first organic layer between the first organic layer and the cathode and containing an electron transporting polymer compound, wherein the hole transporting polymer compound and the electron transporting polymer compound are regulated by specific parameters, at least one of the first organic layer and the second organic layer contains a light emitting material regulated by specific parameters, and light of specific color is emitted from the first organic layer or from the first organic layer or the second organic layer.