OLED Encapsulation with Moisture Absorbent Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic light emitting displays face instability due to moisture and oxygen exposure, which deteriorates device characteristics and shortens lifespan, as the reactive metal cathode and organic material layers are susceptible to oxidation and moisture absorption.
Innovation Solution
An organic light emitting display is designed with a substrate, an organic light emitting diode, an encapsulation substrate, a filler layer, and two encapsulation layers, where the filler and second encapsulation layers include a moisture absorbent, with a specific weight percentage relationship (B-A>0) to effectively suppress moisture and oxygen, using polymers and sealants like epoxy-based resins, and moisture absorbents such as CaO and BaO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass or metal cap is used for encapsulation, then moisture and oxygen protection is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces rigid glass or metal caps with flexible organic encapsulation layers (first and second encapsulation layers) that seal the organic light emitting diode. These thin film layers provide effective moisture and oxygen barrier protection while simplifying the encapsulation structure and reducing manufacturing complexity compared to traditional rigid cap approaches.
Solution Approach 2:
The patent employs composite encapsulation structures combining organic encapsulation layers with inorganic filler layers containing moisture absorbents. This composite approach integrates the barrier properties of organic materials with the moisture-absorbing capabilities of inorganic substances, achieving superior protection without requiring complex glass or metal encapsulation structures.
2Reliability
If the cathode is formed with reactive metal materials, then work function and emission efficiency are improved, but susceptibility to oxidation and moisture absorption increases
Solution Approach 1:
The patent creates an inert protective environment by filling the encapsulation structure with nitrogen gas and incorporating nitrogen-containing polymer compounds in the encapsulation layers. This inert atmosphere prevents oxidation of the reactive metal cathode while maintaining high emission efficiency, effectively isolating the cathode from harmful oxygen and moisture.
Solution Approach 2:
The patent incorporates moisture absorbent materials (such as calcium oxide, barium oxide, or clay) within the encapsulation structure that actively capture and neutralize moisture and oxygen. These materials convert the harmful effects of moisture and oxygen into beneficial moisture-trapping action, protecting the reactive cathode while maintaining device performance.
3Ease of manufacture
If organic material layers are used below the cathode, then device flexibility and manufacturing ease are improved, but susceptibility to rapid deterioration from oxygen and moisture exposure increases
Solution Approach 1:
The patent enhances organic encapsulation layers by incorporating inorganic filler particles (moisture absorbents such as calcium oxide, barium oxide, or clay) within the organic polymer matrix. This composite structure maintains the flexibility and manufacturing advantages of organic materials while adding superior moisture and oxygen barrier properties through the inorganic fillers, preventing rapid deterioration.
Solution Approach 2:
The patent introduces nitrogen-containing polymer compounds as intermediary protective layers between the organic light emitting diode and the external environment. These intermediary layers provide enhanced chemical resistance and barrier properties, protecting the organic material layers from direct exposure to oxygen and moisture while maintaining device flexibility.
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 provides excellent stability by maintaining a low moisture transmittance rate, significantly increasing the lifespan of the organic light emitting display by effectively blocking moisture and oxygen, as demonstrated by the improved water vapor transmission rate and extended lifespan in comparison to comparative examples.
Implementation Method 1
the filler layer and the second encapsulation layer include a moisture absorbent
Implementation Method 2
sealing the substrate and the encapsulation substrate together
Data Source
AI summary
An organic light emitting display includes a substrate; an organic light emitting diode on one surface of the substrate; an encapsulation substrate located opposite and substantially parallel to the substrate with the organic light emitting diode therebetween; a filler layer on one surface of the encapsulation substrate facing the substrate; a first encapsulation layer located between the encapsulation substrate and the substrate and sealing the substrate and the encapsulation substrate together; and a second encapsulation layer located adjacent to the first encapsulation layer and between the encapsulation substrate and the substrate, wherein the filler layer and the second encapsulation layer include a moisture absorbent.