Capping Layer Hydrogen Bond Ratio for Display Reliability
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Solution Overview
Problem
In organic light emitting display devices, hydrogen diffusion from the capping layer into the driving element, such as a thin film transistor, can affect its characteristics and reliability, particularly due to the higher thermal stability of N—H bonds compared to Si—H bonds in the capping layer materials like silicon nitride and silicon oxynitride.
Innovation Solution
A capping layer with a higher hydrogen content of N—H bonds compared to Si—H bonds, specifically a ratio of 16 or more, is used to prevent or reduce hydrogen diffusion into the driving element, thereby minimizing its impact on the driving element's characteristics, and this layer includes silicon compounds like silicon nitride and silicon oxynitride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a capping layer with silicon nitride or silicon oxynitride is used, then the thermal stability is improved, but hydrogen diffusion into the driving element increases
Solution Approach 1:
The patent changes the hydrogen content parameters of the capping layer by controlling the ratio of N—H bond hydrogen content to Si—H bond hydrogen content to be 16 or more. This parameter adjustment reduces hydrogen diffusion into the driving element while maintaining the thermal stability provided by silicon nitride or silicon oxynitride materials.
2Stability of the object's composition
If the hydrogen content of Si—H bond in the capping layer is increased, then the thermal stability is improved, but the hydrogen diffusion into the driving element increases
Solution Approach 1:
The patent optimizes the hydrogen content parameters by limiting the Si—H bond hydrogen content to 0.8 at% or less while maintaining N—H bond hydrogen content sufficiently high to achieve a ratio of 16 or more. This parameter control reduces hydrogen diffusion into the driving element while preserving thermal stability.
Solution Approach 2:
The patent creates different local hydrogen content characteristics within the capping layer by having higher N—H bond hydrogen content compared to Si—H bond hydrogen content. This local quality difference ensures that hydrogen is less likely to diffuse into the driving element while maintaining overall thermal stability.
3Ease of manufacture
If a conventional capping layer is used, then the manufacturing process is simple, but the display quality deteriorates due to hydrogen diffusion
Solution Approach 1:
The patent implements parameter changes during the existing capping layer formation process by controlling deposition conditions to achieve the desired hydrogen content ratio. This approach maintains manufacturing simplicity while improving display quality through reduced hydrogen diffusion into the driving element.
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 approach effectively reduces the diffusion of hydrogen into the driving element, enhancing its reliability and maintaining improved display quality by stabilizing the threshold voltage of the thin film transistor.
Implementation Method 1
a color conversion layer on the light emitting element and converting a wavelength of light emitted from the light emitting element
Implementation Method 2
hydrogen diffusion from the capping layer into the driving element, such as a thin film transistor, can affect its characteristics and reliability
Data Source
AI summary
A display device includes a substrate including first, second, and third light emitting areas and a light blocking area surrounding the first, second, and third light emitting areas, a driving element on the substrate, a light emitting element respectively in each of the first, second, and third light emitting areas on the driving element and electrically connected to the driving element, a color conversion layer including a first color conversion pattern, a second color conversion pattern, and a transmission pattern in the first, second, and third light emitting areas on the light emitting element, respectively, and a capping layer on the color conversion layer and including a silicon compound. A ratio of a hydrogen content of an N—H bond to a hydrogen content of a Si—H bond of the capping layer is about 16 or more.