Continuous Second Electrode for OLED Bezel Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In organic electroluminescence (EL) display units, the second electrode is typically made of moisture-sensitive metals, which deteriorates when exposed to moisture, leading to light emission defects and reliability issues, and existing methods to prevent this, such as using area masks, result in increased bezel sizes and higher costs.
Innovation Solution
The second electrode is formed to extend continuously across the substrate, excluding the terminal region, and is electrically disconnected from the exterior member, eliminating the need for a film formation mask and reducing bezel size by avoiding misalignment margins, while being covered with an insulating film to prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second electrode is formed using an area mask to prevent moisture infiltration, then reliability is improved, but the bezel size increases due to film formation margins
Solution Approach 1:
The patent extracts the area mask from the manufacturing process entirely. The second electrode is formed to extend continuously to the substrate end without requiring mask patterns, eliminating the need for film formation margins and reducing bezel size while maintaining moisture protection through the electrode's continuous coverage
Solution Approach 2:
Instead of using a mask to define where the electrode should be (conventional approach), the patent inverts the approach by forming the electrode continuously to the substrate end and using the substrate edge itself as the boundary, eliminating mask-related margins and reducing bezel size
2Ease of manufacture
If the second electrode extends to the substrate end to reduce bezel size, then manufacturing cost is reduced, but electrical short circuit risk increases
Solution Approach 1:
The patent introduces an insulating film as an intermediary layer between the second electrode and the exterior member. This insulating film prevents electrical short circuits while allowing the electrode to extend continuously to the substrate end, achieving both cost reduction and safety
3Reliability
If the organic insulating film is separated into display region and outer region to suppress moisture diffusion, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the moisture barrier function from the complex separated organic insulating film structure and transfers it to the second electrode itself. The electrode extends continuously across the entire substrate including the outer region, providing moisture protection without requiring separation grooves or selective removal structures
Solution Approach 2:
The second electrode serves multiple functions: it provides electrical conduction for the display region and simultaneously acts as a continuous moisture barrier across the entire substrate including outer regions, eliminating the need for separate moisture barrier structures in different regions
Data Source
AI summary
A display unit includes a display panel including a display region and a terminal region on a first substrate, the display region including a plurality of pixels, each of the plurality of pixels including a light emitting element, and the terminal region including a plurality of terminals at a part of a peripheral region of the display region. The light emitting element includes a first electrode, an organic layer, and a second electrode that is provided commonly to the plurality of pixels, in order from the first substrate side. The second electrode extends, continuously in a plan view, to an end of the first substrate in a region on the first substrate except for the terminal region, and is configured to be electrically disconnected from an exterior member of the display panel.