OLED Barrier Stack With Flattening Layer for Moisture Protection
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Solution Overview
Problem
Organic electroluminescent display devices face challenges in preventing moisture penetration, which can lead to dark spots and deterioration of organic layers, especially due to the limitations of thick silicon nitride barrier films in terms of productivity, cost, and light absorption, as well as the difficulty in forming masks for precise substrate coverage.
Innovation Solution
A multilayered structure comprising a first barrier layer, a flattening layer, and a second barrier layer, where the flattening layer is sporadically formed using a polymeric resin and ultraviolet curing to cover steep elevation changes and foreign bodies, preventing moisture infiltration without requiring additional masks or increasing layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick barrier layer is formed to prevent moisture penetration, then moisture protection is improved, but production cost increases and light transmission is impaired
Solution Approach 1:
The barrier layer is divided into multiple thin layers (first barrier layer, second barrier layer, third barrier layer) instead of forming a single thick layer. Each layer is formed at different temperatures and uses different materials optimized for its specific function, achieving effective moisture protection while controlling production costs and maintaining light transmission.
Solution Approach 2:
Different barrier layers use different material compositions optimized for their specific functions. The first barrier layer uses a material optimized for low-temperature formation and initial protection, the second layer uses a material with enhanced barrier properties, and the third layer uses a material optimized for high-temperature stability and additional protection. This composite approach achieves superior moisture protection compared to a single thick layer while controlling costs.
2Reliability
If a thick barrier layer is formed to prevent moisture penetration, then moisture protection is improved, but light transmission is impaired
Solution Approach 1:
The barrier protection is segmented into multiple thin layers rather than one thick layer. Each thin layer maintains better light transmission properties while collectively providing effective moisture protection. The cumulative effect of multiple thin layers achieves the same protection as a thick layer with significantly improved optical properties.
3Reliability
If the barrier layer thickness is increased to prevent moisture, then protection effectiveness is improved, but device thinness is compromised
Solution Approach 1:
The protective function is segmented across multiple thin layers deposited at different stages of device fabrication. This approach achieves effective moisture protection while maintaining the overall thinness of the device structure, as each individual layer is very thin and the cumulative thickness remains minimal compared to a single thick barrier layer.
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 prevents moisture penetration, ensuring reliable organic semiconductor devices with improved light transmittance and reduced production costs by forming a sporadic, moisture-resistant layer that covers imperfections without thickening the barrier film, thus maintaining the organic layer's integrity and display quality.
Implementation Method 1
forming a flattening layer sporadically existent on the first barrier layer... The flattening layer is formed by vaporously spraying on the supporting substrate in a vacuum environment a solvent having been obtained by mixing a polymeric resin and a polymerization initiator
Implementation Method 2
applying ultraviolet light to the bodies to cause the bodies to be cured and to form a sporadically existent polymeric resin layer
Data Source
AI summary
According to one embodiment, an organic semiconductor device includes a supporting substrate, a plurality of organic EL light emitting elements, a first barrier layer, a flattening layer, and a second barrier layer. The flattening layer exists sporadically and makes gentle in inclination steep elevation change present in the surface of the first barrier layer. The first barrier layer and the second barrier layer are made of moisture penetration preventive material.