Hydrogen Trap Layer in Flexible Organic EL Display Substrates
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Solution Overview
Problem
Organic electroluminescent (EL) display elements are prone to degradation due to moisture and hydrogen diffusion, affecting light emission and transistor characteristics, particularly when low-temperature polycrystalline silicon MOS transistors are used.
Innovation Solution
A display device configuration incorporating a hydrogen trap layer with a metal layer, such as titanium, between two polyimide-based substrates to suppress hydrogen diffusion and oxidation, enhancing the reliability and stability of the organic EL elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polyimide material is used for the flexible substrate, then flexibility and moisture barrier properties are improved, but hydrogen atoms diffuse from the polyimide to the transistor components, degrading device performance
Solution Approach 1:
The hydrogen trap layer serves as an intermediary barrier between the polyimide flexible substrate and the transistor components. It captures hydrogen atoms released by the polyimide before they can migrate to and damage the channel layer and gate insulating film, allowing the use of flexible polyimide substrate without compromising transistor stability.
Solution Approach 2:
The harmful hydrogen atoms are extracted from the diffusion path by the hydrogen trap layer. This layer selectively captures hydrogen atoms that would otherwise migrate from the polyimide substrate to the transistor components, removing the harmful effect while preserving the beneficial flexibility of the polyimide substrate.
2Ease of manufacture
If low-temperature polycrystalline silicon is used for the transistor, then manufacturing temperature is reduced, but transistor characteristics vary due to hydrogen diffusion into the channel layer and gate insulating film
Solution Approach 1:
The hydrogen trap layer acts as a protective intermediary between the polyimide substrate and the low-temperature polycrystalline silicon transistor. It captures hydrogen atoms that would otherwise diffuse into the channel layer and gate insulating film, ensuring consistent transistor characteristics while maintaining the manufacturing advantages of low-temperature processing.
Solution Approach 2:
The hydrogen trap layer provides beforehand cushioning by capturing hydrogen atoms before they can reach and damage the transistor components. This preventive measure protects the transistor from hydrogen-induced degradation, ensuring stable characteristics throughout the device lifetime while allowing low-temperature manufacturing.
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 hydrogen trap layer effectively reduces hydrogen diffusion, maintaining consistent transistor characteristics and preventing degradation of the organic EL elements, thereby improving the display device's reliability and performance.
Implementation Method 1
a middle layer including a metal layer located between the first base and the second base... a hydrogen trap layer with a metal layer, such as titanium, between two polyimide-based substrates to suppress hydrogen diffusion
Implementation Method 2
suppress hydrogen diffusion... effectively reduces hydrogen diffusion, maintaining consistent transistor characteristics
Implementation Method 3
suppress hydrogen diffusion and oxidation, enhancing the reliability and stability of the organic EL elements
Data Source
AI summary
According to one embodiment, a display device includes a first base, a second base, a middle layer including a metal layer located between the first base and the second base, and a circuit unit and a display element unit located above the second base.