OLED Cathode Contact Resistance and Aperture Ratio
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Solution Overview
Problem
Conventional organic electroluminescent display devices suffer from a deteriorated aperture ratio due to the cell driving part being formed on the same substrate as the light-emitting cell, leading to reduced image quality and increased production costs.
Innovation Solution
The solution involves forming an organic electroluminescent display device with a substrate that includes switching and driving transistors, a passivation layer with contact holes, and a light-emitting cell with a cathode electrode made of Aluminum-Neodymium and an anode electrode, where the gate and data pad top electrodes, as well as the contact electrode, are made of Molybdenum-Titanium, reducing contact resistance and production processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the cell driving part is formed on the same substrate as the light-emitting cell, then the device integration is improved, but the aperture ratio deteriorates
Solution Approach 1:
The patent transitions from a planar integration approach to a three-dimensional stacked structure. The light-emitting cell and cell driving part are arranged in different layers vertically, allowing both to coexist on the same substrate without occupying the same planar space. This vertical stacking enables high integration while preserving the aperture ratio of the light-emitting cell.
2Reliability
If multiple layers of electrodes and contact holes are formed, then the electrical connection is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent combines multiple electrode layers and contact hole formation steps into an integrated multi-layer structure. The first contact holes expose the anode electrode, while the second contact holes expose the cathode electrode, with both sets of contact holes and electrodes formed in a coordinated manner. This merging of steps improves electrical connection reliability while managing manufacturing complexity through systematic process integration.
3Reliability
If the contact electrode is made acid-resistant, then the etching process reliability is improved, but the material selection is restricted
Solution Approach 1:
The patent changes the chemical property parameter of the contact electrode material by selecting materials with acid-resistant characteristics. This parameter change ensures that the contact electrode remains intact during the etching process used to form contact holes, improving etching process reliability. The specific acid-resistant material properties are chosen to match the etching chemistry used in the fabrication process.
Data Source
AI summary
A method for fabricating an organic electroluminescent display device is provided. The organic electroluminescent display device includes a light-emitting cell having a cathode electrode, an anode electrode and an organic layer interposed therebetween; wherein the cathode electrode is electrically connected to a contact electrode via a contact hole; wherein the contact electrode has acid-resistance with respect to an etchant used in patterning the cathode electrode.