OLED Encapsulation Stack for Curved-Edge Display Reliability
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Solution Overview
Problem
Existing display devices face challenges in maintaining reliability, particularly in designs that incorporate bent or curved edges and corners, where encapsulation layers may not adequately protect the organic light emitting elements.
Innovation Solution
The display device incorporates a substrate with protruding patterns, a pixel electrode, a pixel defining layer, a light emitting layer, a common electrode, and multiple encapsulation layers, including an overcoat layer with sensitizers, to enhance structural integrity and protection of the organic light emitting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the display device uses bent or curved edges and corners to achieve complex geometries, then the design versatility is improved, but the encapsulation layers may not adequately protect the organic light emitting elements, worsening the reliability
Solution Approach 1:
The encapsulation structure is divided into multiple inorganic encapsulation layers (first, second, and third layers) with different material compositions and functions. Each layer provides specific protection against moisture and oxygen, ensuring adequate protection even in bent or curved geometries where single-layer encapsulation would fail.
Solution Approach 2:
The patent employs composite encapsulation layers combining different inorganic materials (such as aluminum oxide, silicon oxide, titanium oxide) with varying barrier properties. This composite structure provides enhanced protection against environmental factors while maintaining flexibility for complex device geometries.
2Reliability
If multiple inorganic encapsulation layers are added to improve protection, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The encapsulation function is segmented into multiple specialized layers, each with specific material composition and thickness optimized for particular protection needs. This segmentation allows for targeted protection without requiring a uniformly complex structure throughout the entire device.
Solution Approach 2:
The pixel defining layer serves multiple functions: it defines the light emitting area boundaries, provides structural support, and acts as a base for the encapsulation layers. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while maintaining reliability.
3Use of energy by moving object
If the pixel defining layer exposes the pixel electrode in the light emitting area, then the light emitting efficiency is improved, but the risk of environmental damage to the exposed electrode increases, worsening the reliability
Solution Approach 1:
The pixel defining layer is formed to expose the pixel electrode in the light emitting area before the encapsulation layers are deposited. This preliminary configuration optimizes light emitting efficiency, and subsequent encapsulation layers are then applied to protect the exposed electrode, resolving the contradiction between efficiency and protection.
Solution Approach 2:
Multiple inorganic encapsulation layers are applied in advance to provide protective coverage over the exposed pixel electrode in the light emitting area. This beforehand protection prevents environmental damage while maintaining the electrode's exposure for efficient light emission.
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 configuration improves the reliability and durability of display devices by ensuring effective encapsulation and protection of the light emitting elements, even in designs with complex geometries such as bent edges and corners.
Implementation Method 1
an OLED displays an image using an organic light emitting element that generates light through recombination of electrons and holes
Implementation Method 2
The overcoat layer may include at least any one of a negative type sensitizer and a positive type sensitizer
Data Source
AI summary
A display device includes a substrate which includes a base part and a protruding pattern which protrudes from the base part, a pixel electrode which is on the protruding pattern, a pixel defining layer which is d on the pixel electrode and exposes the pixel electrode, a light emitting layer which is on the pixel electrode exposed by the pixel defining layer, a common electrode which is on the light emitting layer, a first inorganic encapsulation layer which is on the common electrode, a second inorganic encapsulation layer which is on the first inorganic encapsulation layer, and an overcoat layer which is on the second inorganic encapsulation layer. The pixel defining layer defines a light emitting area, and the first inorganic encapsulation layer and the second inorganic encapsulation layer are in direct contact with each other in the light emitting area.