OLED Intermediate Layer Thickness for Thin Moisture-Resistant Encapsulation
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Solution Overview
Problem
Existing organic light emitting display apparatuses face challenges in achieving enhanced encapsulation characteristics while maintaining a small thickness, primarily due to issues with moisture and impurity protection.
Innovation Solution
A display apparatus is designed with a first and second pixel electrode, a pixel definition layer, an intermediate layer with a through hole, an opposite electrode, and an inorganic encapsulation layer, which enhances encapsulation while maintaining a thin structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an encapsulation member is formed over the organic light emitting diode to prevent moisture and impurities, then encapsulation characteristics are improved, but the thickness of the display apparatus increases
Solution Approach 1:
The encapsulation structure is divided into multiple segments: a first encapsulation layer (inorganic layer) formed over the pixel electrode and emission layer, and a second encapsulation layer formed over the first encapsulation layer. This segmentation allows each layer to provide specific protective functions while maintaining overall thinness, resolving the contradiction between encapsulation effectiveness and thickness reduction.
Solution Approach 2:
The patent introduces an intermediate layer between the pixel electrode assembly and the opposite electrode, creating an additional dimensional layer for encapsulation. This intermediate layer provides moisture and impurity barrier functionality without significantly increasing the overall device thickness, as it integrates within the existing electrode structure rather than adding external bulk.
2Ease of manufacture
If the intermediate layer has uniform thickness over pixel electrodes and spacer, then manufacturing is simplified, but encapsulation effectiveness is reduced due to moisture pathways through the spacer region
Solution Approach 1:
The intermediate layer is designed with non-uniform thickness: a first thickness over the pixel electrode and a second thickness (greater than the first thickness) over the spacer. This local quality variation ensures that the thicker region over the spacer provides adequate moisture and impurity blocking at the interface, while the thinner region over the pixel electrode maintains overall device thinness. The differentiated thickness profile resolves the contradiction by providing enhanced protection precisely where needed without uniformly increasing thickness throughout.
Data Source
AI summary
A display apparatus includes: a first pixel electrode and a second pixel electrode spaced apart from each other on a substrate; a pixel definition layer including an opening exposing a central portion of each of the first pixel electrode and the second pixel electrode; an intermediate layer on the first pixel electrode, the second pixel electrode, and the pixel definition layer and including a through hole exposing at least a portion of an upper surface of the pixel definition layer between the first pixel electrode and the second pixel electrode; an opposite electrode on the intermediate layer to face the first pixel electrode and the second pixel electrode; and an inorganic encapsulation layer over the opposite electrode.