OLED Pixel Electrode Silver Re-deposition Control
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Solution Overview
Problem
OLED displays face challenges in achieving high luminescence efficiency and yield rate due to issues such as dark spots caused by silver re-deposition during the etching process, which affect display quality and lifespan.
Innovation Solution
The OLED display design incorporates a semi-permeable metal layer with silver or silver alloys, a transparent conductive oxide layer, and an optical property control layer between the insulating layers to prevent silver re-deposition and outgassing, along with a micro-cavity structure with a reflective electrode to enhance luminescence efficiency, and a reduced thickness of the fourth insulating layer to minimize material usage and outgassing effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semi-permeable metal layer containing silver is used in the pixel electrode, then electrical conductivity and light emission are improved, but silver re-deposition during etching causes dark spots and reduces yield rate
Solution Approach 1:
An optical property control layer is introduced as an intermediary between the first insulating layer and the pixel electrode. This layer prevents silver ions from migrating and re-depositing on the insulating layer during the etching process, thereby eliminating dark spots while maintaining the electrical conductivity benefits of the silver-containing semi-permeable metal layer.
Solution Approach 2:
The patent converts the harmful effect of silver re-deposition by using the optical property control layer to capture and control the silver ion migration path. The layer transforms the potential defect (silver re-deposition) into a controlled process where silver ions are directed away from critical areas, maintaining electrode functionality while preventing display defects.
2Reliability
If multiple insulating layers are used to cover electrodes, then electrical insulation and structural stability are improved, but outgassing during manufacturing increases and affects luminescence efficiency
Solution Approach 1:
The patent applies local quality by making the fourth insulating layer thinner at specific locations (where it covers the pixel electrode end) compared to other areas. This localized thickness variation reduces the total organic material volume that can outgas, while maintaining sufficient insulation where needed. The fourth insulating layer thickness is specifically controlled to be less than that of the third insulating layer in the aperture region.
Solution Approach 2:
The patent changes the physical parameter of insulating layer thickness to optimize performance. By reducing the thickness of the fourth insulating layer in specific regions, the amount of organic material is minimized, thereby reducing outgassing during manufacturing while maintaining adequate electrical insulation and structural support where required.
3Productivity
If the fourth insulating layer is made thinner to reduce outgassing, then luminescence efficiency is improved, but electrical insulation and protective coverage may be compromised
Solution Approach 1:
The fourth insulating layer is designed with spatially varying thickness: thinner in the aperture region where reduced outgassing is critical for luminescence efficiency, and thicker in other regions where electrical insulation and protective coverage are prioritized. This local differentiation allows simultaneous optimization of both luminescence efficiency and electrical insulation reliability.
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
This configuration significantly reduces dark spots, improves luminescence efficiency, and extends the lifespan of the OLED display by preventing silver re-deposition and minimizing outgassing, resulting in higher yield rates and improved display quality.
Implementation Method 1
an opposite electrode arranged on the intermediate layer and including a reflective material
Implementation Method 2
a micro-cavity structure with a reflective electrode to enhance luminescence efficiency
Implementation Method 3
an optical property control layer interposed between the first insulating layer and the pixel electrode
Implementation Method 4
a reduced thickness of the fourth insulating layer to minimize material usage and outgassing effects
Implementation Method 5
holes injected from the hole injection electrode and electrons injected from the electron injection electrode are recombined and emit light during decay
Data Source
AI summary
An organic light-emitting diode (OLED) display is disclosed. In one aspect, the OLED display includes a thin film transistor including an active layer, a gate electrode, a source electrode, and a drain electrode, a first insulating layer arranged between the active layer and the gate electrode, and a second insulating layer arranged between the gate, source, and drain electrodes. The OLED display also includes a third insulating layer covering the source and drain electrodes, wherein an opening is defined in each of the second and third insulating layers and wherein the openings substantially overlap. The OLED display further includes a pixel electrode formed in the openings defined in the second and third insulating layers and including a semi-permeable metal layer.