OLED Pattern Layer for Charge Injection Barrier Reduction
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Solution Overview
Problem
Existing organic light emitting devices face challenges in minimizing the energy barrier for charge injection and extraction between electrodes and organic material layers, leading to increased drive voltage and instability due to material interface issues and energy level differences.
Innovation Solution
Incorporating a pattern layer between the conductive layers and organic material layers, formed from organic, inorganic, or mixed materials, to lower the electrical barrier for charge injection and transport, allowing for a wider range of electrode materials and various light emitting forms by forming pattern layers corresponding to the light emitting region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional organic light emitting device structure is used without a pattern layer, then the device structure is simple, but the energy barrier for charge injection and extraction between electrodes and organic material layers is high, leading to increased drive voltage
Solution Approach 1:
The patent introduces a pattern layer as an intermediary component between the electrode and the organic material layer. This pattern layer serves as a mediator that facilitates charge injection and extraction by providing favorable energy levels and interfaces, thereby reducing the energy barrier and drive voltage without significantly complicating the overall device structure.
Solution Approach 2:
The pattern layer is formed in a localized manner only in the light-emitting region where charge injection is needed, rather than covering the entire electrode surface. This local quality approach reduces the energy barrier where it is most needed while maintaining simplicity in non-emitting regions, thus improving charge injection efficiency without proportionally increasing device complexity.
2Ease of manufacture
If electrode materials are selected without considering energy level matching, then material selection is easy, but the interface stability between electrode and organic material layer deteriorates
Solution Approach 1:
The pattern layer acts as an intermediary that buffers the interface between the electrode and organic material layer. It provides energy level matching and chemical compatibility, ensuring stable interfaces even when electrode materials are selected for ease of manufacture rather than precise energy level matching. This mediator layer prevents direct adverse interactions at the interface.
Solution Approach 2:
The pattern layer modifies the energy level parameters at the electrode-organic material interface. By introducing materials with appropriate HOMO and LUMO energy levels, it creates favorable energy gradients that facilitate charge injection and extraction while stabilizing the interface, thus decoupling material selection ease from interface stability requirements.
3Device complexity
If the energy barrier for charge injection is not minimized, then the device structure remains simple, but the charge injecting ability deteriorates
Solution Approach 1:
The pattern layer serves as a specialized intermediary component designed specifically to minimize the energy barrier for charge injection. It provides optimal energy levels and interface properties that facilitate efficient charge transfer between the electrode and organic material layer, thereby improving charge injecting ability without significantly increasing overall device structural complexity.
4Reliability
If a pattern layer is added to lower the energy barrier, then the charge injecting ability improves, but the device structure becomes more complex
Solution Approach 1:
The pattern layer is implemented locally only in the light-emitting regions where charge injection is required, rather than throughout the entire device. This localized approach improves charge injecting ability where needed while minimizing the increase in overall device structural complexity in non-emitting regions.
Solution Approach 2:
The device structure is segmented into functional regions: areas with the pattern layer for charge injection and light emission, and areas without it for other functions. This segmentation allows the pattern layer to be added only where necessary to improve charge injecting ability, thereby limiting the increase in overall device complexity.
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 approach improves charge injecting ability, reduces the energy barrier, and enables the use of a broader range of materials for electrodes, enhancing the light emitting mechanism and allowing for various light emitting forms such as bottom, top, or dual emission.
Implementation Method 1
a pattern layer which is capable of lowering the energy barrier from an electrode for charge injection or charge extraction to an organic material layer
Data Source
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Figure 4
AI summary
The present invention provides an organic light emitting device comprising: a substrate; a first conductive layer and a second conductive layer, which are sequentially positioned on the substrate; and at least one organic material layer, including a light emitting layer, which is interposed between the first conductive layer and the second conductive layer; wherein the organic light emitting device comprises a pattern layer formed corresponding to the light emitting region between at least one organic material layer and at least one conductive layer of the first conductive layer and the second conductive layer; charges are injected or transported between the conductive layer and the organic material layer through the pattern layer; and charges are not directly injected or transported in the region in which two layers each in contact with the upper surface and the lower surface of the pattern layer are directly in contact, and a method for preparation thereof.