OLED Electrode Edge Protection Structure Against Vertical Current Leakage
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Solution Overview
Problem
Current leakage in display devices, particularly in head-mounted displays, is a significant issue that affects the performance and reliability of these devices.
Innovation Solution
The display device incorporates a substrate with a first electrode, a pixel defining layer, and protective layers made of different materials, including a first protective layer of insulating metal oxide and a second protective layer of metal or transparent conductive oxide, designed to prevent short circuits and vertical current leakage by ensuring the second protective layer is narrower than the first, with an undercut shape to align edges and maintain electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single protective layer is used between the first electrode and pixel defining layer, then the structure is simple, but current leakage occurs in the vertical direction
Solution Approach 1:
The protective layer is divided into two distinct layers: a first protective layer (insulating material) positioned between the first electrode and pixel defining layer, and a second protective layer positioned between the first protective layer and pixel defining layer. This segmentation allows each layer to perform specific functions - the first layer provides primary insulation while the second layer provides additional protection and structural support, together preventing vertical current leakage more effectively than a single layer could.
Solution Approach 2:
The patent employs composite materials by using different materials for the two protective layers. The first protective layer uses insulating material (such as organic insulators or inorganic insulators like silicon oxide or silicon nitride), while the second protective layer uses different insulating material. This composite structure leverages the complementary properties of different materials to achieve superior current leakage prevention compared to using a single material type.
2Reliability
If the second protective layer has the same width as the first protective layer, then the manufacturing process is simpler, but short circuits may occur between electrodes
Solution Approach 1:
The patent introduces asymmetry in the protective layer structure by making the second protective layer narrower than the first protective layer in the cross-sectional direction. The first protective layer extends further laterally to provide comprehensive insulation coverage, while the second protective layer is positioned more centrally. This asymmetric design ensures that the wider first protective layer prevents short circuits between adjacent electrodes, while the narrower second protective layer provides focused protection where most needed, achieving superior electrical insulation without requiring precise width alignment.
3Reliability
If the first protective layer is made of conductive material, then electrical conductivity is improved, but current leakage increases in the vertical direction
Solution Approach 1:
The patent applies local quality by using insulating materials specifically in the regions where vertical current leakage prevention is needed. Both the first protective layer (in contact with the first electrode) and the second protective layer are made of insulating materials at the locations where they interface with electrodes and the pixel defining layer. This localized use of insulating properties ensures that current leakage is prevented at critical interfaces while allowing the overall device structure to maintain necessary electrical conductivities in other regions through different material choices.
Data Source
AI summary
A display device is disclosed that includes a substrate, a first electrode, a pixel defining layer, a first protective layer, a second protective layer, a light emitting layer, and a second electrode. The first electrode is positioned on the substrate. The pixel defining layer overlaps an edge region of the first electrode. The first protective layer is positioned between the first electrode and the pixel defining layer and overlaps the edge region of the first electrode. The second protective layer is positioned between the first protective layer and the pixel defining layer and overlaps the edge region of the first electrode. The light emitting layer is positioned on the first electrode. The second electrode is positioned on the light emitting layer. The second protective layer has a smaller cross-sectional width than the first protective layer. The first protective layer and the second protective layer include different materials.