OLED Encapsulation Layer with Hydrophobic Element for Hydrogen Diffusion
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Solution Overview
Problem
Thin film transistors using oxide semiconductors in organic light-emitting display devices face reliability issues due to hydrogen diffusion from inorganic films, which reacts with oxygen and alters the threshold voltage, leading to deterioration.
Innovation Solution
An organic light-emitting display device with an encapsulation unit comprising multiple inorganic encapsulation layers and an organic encapsulation layer, where the inorganic encapsulation layers include inorganic insulation layers and an element encapsulation layer formed using hydrophobic and inert elements to prevent hydrogen and oxygen permeation, thereby reducing the impact on the thin film transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic films are formed by PECVD on thin film transistors using oxide semiconductors, then the inorganic film provides encapsulation and protection, but hydrogen content in the inorganic film (15-30%) diffuses into the active layer and reacts with oxygen, causing deterioration of transistor reliability
Solution Approach 1:
An element encapsulation layer containing hydrophobic elements (such as fluorine) or inert elements is introduced between the inorganic insulation layer and the oxide semiconductor active layer. This intermediary layer prevents hydrogen from the inorganic film from diffusing into and reacting with oxygen in the active layer, thereby resolving the harmful effect while maintaining the protective function of the inorganic encapsulation structure.
Solution Approach 2:
The encapsulation structure is designed as a composite multi-layer system combining inorganic insulation layers (such as silicon oxide or silicon nitride) with an element encapsulation layer containing hydrophobic or inert elements. This composite structure leverages the protective properties of inorganic materials while adding the hydrogen-blocking functionality of the element encapsulation layer, achieving both protection and prevention of hydrogen-induced deterioration.
2Object-affected harmful factors
If multiple inorganic encapsulation layers are used to block hydrogen, then hydrogen diffusion is reduced, but the device complexity and manufacturing process become more complicated
Solution Approach 1:
The encapsulation function is segmented into distinct layers: an inorganic insulation layer providing physical protection and barrier properties, and an element encapsulation layer containing hydrophobic or inert elements specifically targeted at blocking hydrogen diffusion. This segmentation allows each layer to perform its specialized function efficiently without requiring multiple redundant inorganic layers, thereby reducing overall device complexity while maintaining effective hydrogen protection.
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 the deterioration of thin film transistors by blocking moisture and gas permeation, improving the reliability and stability of the devices by minimizing variations in threshold voltage and enhancing negative bias temperature illumination stress performance.
Implementation Method 1
at least one element encapsulation layer between the inorganic insulation layers, the at least one element encapsulation layer including at least one of: a hydrophobic element and an inert element
Implementation Method 2
the at least one element encapsulation layer including at least one of: a hydrophobic element and an inert element
Data Source
AI summary
An organic light-emitting display device and a method of manufacturing the same are provided. An organic light-emitting display device includes: a light-emitting element on a substrate, and an encapsulation unit on the light-emitting element, the encapsulation unit including: a plurality of inorganic encapsulation layers, at least one of the inorganic encapsulation layers including: a plurality of inorganic insulation layers, and at least one element encapsulation layer between the inorganic insulation layers, the at least one element encapsulation layer including at least one of: a hydrophobic element and an inert element, and at least one organic encapsulation layer between the inorganic encapsulation layers.