Inorganic Insulating Layer Ammonia Suppression in OLED Displays
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Solution Overview
Problem
The generation of ammonia in organic EL display devices due to moisture reaction with nitrogen-containing films leads to color loss and defects in the polarizing plate, compromising the display's reliability.
Innovation Solution
A layered structure of inorganic insulating films with a second inorganic insulating layer having a lower N—H bond density per unit area, formed using specific CVD conditions, is used to suppress ammonia generation and oxidation, thereby protecting the polarizing plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nitrogen-containing inorganic insulating layer is used to suppress moisture penetration, then moisture barrier performance is improved, but ammonia generation increases causing polarizing plate defects
Solution Approach 1:
The sealing film is divided into multiple inorganic insulating layers with different functions: the first layer (SiNx) provides moisture barrier performance, while the second layer (SiOx or SiOxNy) with lower N-H bond density suppresses ammonia generation. This segmentation allows each layer to specialize in one function, resolving the contradiction between moisture barrier and ammonia suppression.
Solution Approach 2:
The second inorganic insulating layer acts as an intermediary between the moisture environment and the polarizing plate. It serves as a buffer that prevents direct interaction between moisture-reactive nitrogen-containing films and the polarizing plate, thereby suppressing ammonia generation while maintaining moisture barrier performance.
2Reliability
If the N—H bond density in the inorganic insulating layer is increased to improve moisture sealing, then moisture prevention is enhanced, but ammonia generation and oxidation increase
Solution Approach 1:
Different regions of the sealing structure have different compositional qualities: the first inorganic insulating layer has high N-H bond density for moisture sealing, while the second layer has low N-H bond density for ammonia suppression. This local quality differentiation allows each region to optimize for its specific function without compromising the other.
Solution Approach 2:
The sealing film uses a composite structure of two different inorganic insulating materials: SiNx (first layer) and SiOx or SiOxNy (second layer). This composite material approach combines the moisture barrier properties of nitrogen-rich films with the low ammonia-generation properties of oxygen-rich films, resolving the contradiction between sealing performance and oxidation resistance.
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 solution effectively reduces ammonia generation, preventing color loss and improving the reliability of the display device by using a denser, less oxidizable second inorganic insulating layer in contact with the resin mask, which minimizes reactions with moisture and nitrogen-containing films.
Implementation Method 1
a second inorganic insulating layer arranged above the organic insulating layer and having a N—H bond total weight measured by an FT-IR method lower than a N—H bond total weight per unit area of the first inorganic insulating layer
Implementation Method 2
a first sealing film and a second sealing film comprised form an inorganic material such as a silicon nitride film or silicon oxide film are arranged above a light emitting element
Data Source
AI summary
A display device includes a first substrate, a display region arranged with a pixel including a light emitting element above the first substrate, a first inorganic insulating layer covering the display region, an organic insulating layer arranged above the first inorganic insulating layer, a second inorganic insulating layer arranged above the organic insulating layer and having a N—H bond total weight measured by an FT-IR method lower than a N—H bond total weight per unit [% area] of the first inorganic insulating layer, and a polarizing plate arranged above the second inorganic insulating layer.