OLED Transparent Anode and Protective Layer for Plasma Damage Prevention
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Solution Overview
Problem
The fabrication of organic electro-luminescent displays (OELDs) faces challenges in protecting pixel circuits from damage during the formation process, particularly due to high-energy plasma and organic liquid materials used in the formation of organic light emitting diodes (OLEDs).
Innovation Solution
A protective layer made of the same material as the transparent lower electrode, such as indium tin oxide or indium zinc oxide, is formed over the pixel circuit to prevent damage from plasma and organic materials during the OLED formation process, while the transparent lower electrode is formed in a different area to allow light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma surface treatment is performed on the anode to improve adhesion and clean the surface, then the quality of the OLED interface is improved, but the pixel circuit transistors are damaged by high-energy plasma penetrating the passivation layer
Solution Approach 1:
The patent divides the treatment area by introducing a protective layer that selectively covers the transistor region while leaving the OLED region exposed. This segmentation allows plasma treatment to be applied only where needed (at the OLED-anode interface) without damaging the transistor components, thus resolving the contradiction between improving interface quality and maintaining transistor integrity
Solution Approach 2:
The protective layer is formed before the plasma surface treatment step. This preliminary action establishes a shield that prevents plasma damage to transistors before the harmful plasma exposure occurs, allowing the subsequent plasma treatment to safely improve OLED interface quality without compromising transistor reliability
2Area of stationary object
If the OLED is formed to occupy a large portion of the pixel to improve display area, then the brightness and visibility are improved, but the pixel circuit becomes more vulnerable to damage from organic liquid materials
Solution Approach 1:
The protective layer is strategically positioned to cover only the transistor region while allowing the OLED to occupy the maximum available area for light emission. This segmentation enables the OLED to expand across the pixel area for improved display brightness and visibility, while the protected transistor region maintains reliability against organic liquid material damage
Solution Approach 2:
The protective layer acts as an intermediary barrier between the organic liquid materials used in OLED formation and the pixel circuit transistors. This intermediary shield allows the OLED to be formed with extended area coverage using liquid materials without direct contact damage to the transistors, thus enabling larger display area while maintaining circuit 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
The protective layer effectively shields the pixel circuit from plasma and organic liquid material damage, ensuring the integrity and functionality of the OELD during fabrication, particularly applicable to both top and bottom emission types.
Implementation Method 1
In the fabrication of the OELD, a plasma surface treatment is performed on an anode formed of a transparent material such as indium tin oxide ("ITO").
Implementation Method 2
Organic electro-luminescent displays ("OELDs") are self-luminescent displays which use an organic compound as a luminescent material.
Data Source
AI summary
In an organic electro-luminescent display, a pixel circuit is disposed in a unit pixel region defined on a substrate. A passivation layer covers the entire unit pixel region including the pixel circuit. An organic light emitting diode (“OLED”) including a transparent lower electrode formed on a portion of the passivation layer which does not overlap the pixel circuit, an OLED layer, and an upper electrode are sequentially formed on the passivation layer. The transparent lower electrode is a transparent anode of the OLED. A protective layer is formed of the same material as the transparent lower electrode and disposed on a portion of the passivation layer corresponding to the pixel circuit to cover and protect the pixel circuit.