OLED Display Substrate Parallel Electrode IR Drop Reduction
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Solution Overview
Problem
In organic light emitting diode (OLED) display panels, the formation of the cathode layer by sputtering ITO can damage the organic functional layer, while evaporation of partially transparent metal materials results in high resistance, leading to reduced luminous efficiency and picture quality due to increased IR drop.
Innovation Solution
A display substrate with a base substrate having pixel areas featuring a first electrode layer, an organic functional layer, and a second electrode layer, with a third transparent electrode layer electrically connected in parallel to the second electrode layer, and optionally a transparent dielectric layer between them, to reduce IR drop and maintain luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO is sputtered to form the cathode layer, then the organic functional layer can be protected from damage, but the manufacturing process damages the organic functional layer
Solution Approach 1:
The patent introduces a buffer layer as an intermediary between the ITO cathode layer and the organic functional layer. This buffer layer serves as a mediator that prevents direct contact and potential damage from the sputtering process, while still allowing electrical functionality. The buffer layer absorbs the harmful effects of the sputtering process and transmits only the necessary electrical function to the organic layer.
Solution Approach 2:
The cathode structure is segmented into multiple functional layers: the ITO layer for electrical conduction, the buffer layer for protection, and the organic functional layer for light emission. This segmentation allows each layer to perform its specific function optimally without interfering with or damaging other layers.
2Ease of manufacture
If partially transparent metal materials are evaporated to form the cathode layer, then the formation process is simpler, but the resistance increases leading to reduced luminous efficiency
Solution Approach 1:
The cathode structure uses a composite of multiple materials: ITO provides low electrical resistance, the buffer layer provides protection and interface functionality, and the organic functional layer provides light emission. This composite structure combines the advantages of different materials to achieve both ease of manufacture and high luminous efficiency.
Solution Approach 2:
The patent merges multiple functions into a single cathode structure: electrical conduction (ITO), protection (buffer layer), and light emission (organic functional layer). This merging allows the system to achieve multiple objectives simultaneously - simple formation process and high luminous efficiency - that cannot be achieved with a single material or layer.
3Loss of energy
If a transparent dielectric layer is added between the second and third electrode layers, then the IR drop is reduced, but the device structure becomes more complex
Solution Approach 1:
The transparent dielectric layer performs multiple functions simultaneously: it provides electrical insulation between the second and third electrode layers, reduces IR drop through its dielectric properties, and maintains optical transparency. This multi-functionality justifies the additional structural element by delivering multiple benefits from a single component.
Solution Approach 2:
The patent optimizes parameters of the transparent dielectric layer including its thickness, dielectric constant, and transparency characteristics to achieve the desired balance between reducing IR drop and maintaining structural simplicity. By carefully selecting these parameters, the layer provides maximum benefit with minimum added 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
The solution effectively reduces IR drop across the second electrode layer, maintaining high picture quality and luminous efficiency by providing a parallel path with equivalent resistance, while the transparent design avoids light interference.
Implementation Method 1
a transparent dielectric layer between the second electrode layer and the third electrode layer
Implementation Method 2
the third electrode layer is electrically connected to the second electrode layer
Data Source
AI summary
A display panel and a method for manufacturing the same and a display device are disclosed. The display substrate includes: a base substrate having a plurality of pixel areas, at least one of the plurality of pixel areas including a first electrode layer, an organic functional layer and a second electrode layer stacked in sequence on the base substrate; and a third electrode layer on a side of the second electrode layer facing away from the base substrate; wherein the third electrode layer is electrically connected to the second electrode layer.