Auxiliary Electrode Contact Hole Design for Display Apparatus
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Solution Overview
Problem
In display apparatuses, the process of connecting a second electrode to an auxiliary electrode can damage light-emitting devices due to heat generated by laser irradiation and result in unstable electrical connections, especially when the laser irradiation time is reduced, leading to luminance deviations caused by voltage drops.
Innovation Solution
A display apparatus design featuring a device substrate with an auxiliary electrode and insulating layers, including contact holes with specific inclination angles, allows for electrical connection between the second electrode and the auxiliary electrode without laser irradiation, minimizing damage and ensuring stable connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser irradiation is used to connect the second electrode to the auxiliary electrode, then electrical connection is achieved, but the light-emitting device is damaged due to heat generation
Solution Approach 1:
The patent extracts the harmful laser irradiation process from the connection method. Instead of using laser to remove the light-emitting layer for electrical connection, the invention uses a cold process where the second electrode is formed to directly contact the auxiliary electrode through a contact hole, eliminating heat-induced damage while achieving stable electrical connection.
Solution Approach 2:
The patent introduces an intermediary structure (contact hole with specific inclination angle) that enables electrical connection without direct laser irradiation on the light-emitting device. The contact hole serves as a mediator that allows the second electrode to reach the auxiliary electrode through a controlled path, avoiding harmful heat effects.
2Object-affected harmful factors
If laser irradiation time is reduced to minimize damage, then heat damage is decreased, but electrical connection becomes unstable due to residual light-emitting layer
Solution Approach 1:
The patent applies preliminary action by pre-forming the contact hole with a specific inclination angle before forming the second electrode. This preliminary structure ensures that when the second electrode is formed, it naturally contacts the auxiliary electrode through the inclined contact hole wall, guaranteeing stable electrical connection without requiring extended laser irradiation that would cause heat damage.
Solution Approach 2:
The patent changes the geometric parameter of the contact hole (inclination angle) to optimize the connection process. By setting the contact hole inclination angle to be greater than the bank insulating layer inclination angle, the structure ensures proper contact between the second electrode and auxiliary electrode, achieving reliable electrical connection without excessive laser irradiation.
3Reliability
If conventional connection process is used, then electrical connection is achieved, but luminance deviation occurs due to voltage drop
Solution Approach 1:
The patent uses a disposable-like approach with the contact hole structure that is specifically designed to facilitate reliable electrical connection. The contact hole with its specific inclination angle serves as a dedicated connection pathway that ensures low-resistance contact between the second electrode and auxiliary electrode, preventing voltage drop and luminance deviation.
Data Source
AI summary
A display apparatus can include pixel areas and a contact area between the pixel areas. An auxiliary electrode can be disposed in the contact area. Each of the pixel areas can include a light-emitting device on a device substrate. An insulating layer including at least one contact hole overlapping with the contact area can be disposed on the device substrate. A connection electrode electrically connected to the auxiliary electrode can extend along a sidewall and a bottom surface of the contact hole. A light-emitting layer and a second electrode of the light-emitting device in each pixel area can extend inside of the contact hole. Thus, in the display apparatus, a process of forming the second electrode and the connection electrode can be simplified, and damage of the light-emitting device due to a process of connecting the second electrode and the connection electrode can be minimized.