Island-Shaped Barrier Layers for OLED Moisture Protection
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Solution Overview
Problem
Organic electroluminescent devices are prone to degradation due to water permeation, leading to the formation of dark spots, as existing moisture-proof inorganic barrier layers can have defects allowing water to penetrate, and heating the planarizing layer can exacerbate this issue.
Innovation Solution
The use of island-shaped barrier layers made of silicon nitride or silicon oxynitride on the substrate, along with a light reflection layer and an insulating layer, to prevent water from reaching the electroluminescent elements, combined with a top emission structure that allows water vaporization through regions without barrier layers during manufacturing, ensuring minimal water content and preventing dark spot formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a moisture-proof inorganic barrier layer is formed over the entire surface of the planarizing layer, then water permeation is prevented, but defects such as pinholes allow water to penetrate and cause dark spots
Solution Approach 1:
The patent applies local quality by forming barrier layers only in specific regions where electroluminescent elements are disposed, rather than covering the entire planarizing layer surface. This localized approach concentrates protective function where needed while reducing the probability of defects affecting the overall structure.
Solution Approach 2:
The barrier protection is segmented into multiple discrete barrier layers corresponding to individual electroluminescent elements or groups of elements. This segmentation isolates potential defect regions, preventing water penetration from one defective barrier layer from affecting adjacent elements.
2Reliability
If the planarizing layer contains water, then heating by TFTs and luminescent layer causes water to transfer and permeate into the luminescent layer, but forming barrier layers before heating allows water vaporization through regions without barrier layers
Solution Approach 1:
The patent applies preliminary action by forming barrier layers on the planarizing layer before completing the electroluminescent element structure. This timing allows subsequent heating processes to vaporize and remove water through regions without barrier layers (such as inter-element regions) before the luminescent layer is formed, preventing water-induced defects.
Solution Approach 2:
The patent converts the potentially harmful water contained in the planarizing layer into a removable substance by utilizing heating processes. The water vaporizes and is eliminated through regions without barrier layers, transforming a harmful contaminant into a temporary intermediate that is subsequently removed.
3Reliability
If barrier layers are formed in an island-shaped manner, then water is prevented from reaching electroluminescent elements, but regions without barrier layers are exposed to water vapor during heating
Solution Approach 1:
The barrier protection is segmented into multiple discrete barrier layers corresponding to individual electroluminescent elements or groups of elements. This segmentation isolates potential defect regions, preventing water penetration from one defective barrier layer from affecting adjacent elements.
Solution Approach 2:
The patent uses regions without barrier layers (such as inter-element regions) as intermediary pathways for water vapor removal. These intermediary regions allow water vapor to escape during heating processes without requiring the barrier layers to be continuous across the entire surface.
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 water-induced degradation of light-emitting characteristics in electroluminescent devices by minimizing water presence and ensuring reliable barrier protection, thereby reducing the occurrence of dark spots and enhancing device reliability.
Implementation Method 1
each barrier layer prevents water from transferring from the substrate to the electroluminescent element
Implementation Method 2
water contained in the substrate can be vaporize and released to the outside through the regions having no barrier layer
Implementation Method 3
water is heated by heat from the TFTs and the luminescent layer
Data Source
AI summary
An electroluminescent device includes a substrate and a plurality of electroluminescent elements disposed on the substrate. Each electroluminescent element includes a first electrode, a second electrode, and a function layer including a luminescent layer and disposed between the first electrode and the second electrode. The electroluminescent elements are grouped into a plurality of groups each including at least one electroluminescent element. Barrier layers are disposed in an island-shaped manner corresponding to regions where the electroluminescent elements are disposed, and each barrier layer prevents water from transferring from the substrate to the electroluminescent element in the corresponding group.