OLED Protection Layer Structure for Stress-Balanced Pixel Reliability
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Solution Overview
Problem
Organic light emitting display devices face reduced image quality due to misformation of organic light emitting layers across pixels, leading to color mixing and decreased durability.
Innovation Solution
A display device structure incorporating a protection layer with different stress directions for the first and second protection patterns, including a transparent conductive material and inorganic materials respectively, and an encapsulation layer with inorganic and organic layers to enhance durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single protection layer is used to protect the organic light emitting element, then the manufacturing process is simple, but the durability and reliability are insufficient
Solution Approach 1:
The protection layer is divided into multiple sub-layers (first protection layer, second protection layer, third protection layer) with different materials and functions. Each layer addresses specific protection needs: the first layer provides basic protection, the second layer adds stress management with opposite stress directions, and the third layer enhances chemical resistance, collectively improving durability without excessive complexity
Solution Approach 2:
The patent employs composite material structure where different protection layers are made from different materials (organic materials, inorganic materials, transparent conductive materials) to provide complementary properties. This composite approach allows each layer to contribute its strengths, achieving superior overall protection and reliability
2Manufacturing precision
If the organic light emitting layer is formed without precise pixel alignment, then the manufacturing process is easier, but color mixing occurs and image quality deteriorates
Solution Approach 1:
The pixel defining layer is formed beforehand to establish precise pixel boundaries before depositing the organic light emitting layer. This preliminary structuring creates physical barriers that confine the organic material to specific pixel regions, preventing misformation and color mixing while maintaining manufacturing feasibility through sequential processing steps
Solution Approach 2:
The pixel defining layer acts as an intermediary structure between the substrate and the organic light emitting layer. It provides a controlled interface that guides material deposition and prevents organic material from spreading into adjacent pixels, thereby ensuring precise pixel alignment without requiring extremely complex manufacturing processes
3Reliability
If protection layers with uniform stress are used, then the manufacturing process is simpler, but the structural integrity and durability are reduced
Solution Approach 1:
The second protection layer is designed to exhibit stress in a direction opposite to that of the first protection layer. This counterbalancing stress arrangement compensates for stress-induced deformations and enhances the overall structural integrity of the protection layer system, improving durability through stress management
Solution Approach 2:
The patent deliberately changes the stress parameter of the protection layers by selecting materials and deposition conditions that produce opposite stress directions. This parameter variation allows the layers to counterbalance each other's stress, preventing warping and improving structural stability without requiring overly complex stress control mechanisms
Data Source
AI summary
A display device includes: a circuit element layer comprising a transistor; a display element layer comprising a first electrode connected to the transistor, a second electrode facing the first electrode, an organic pattern between the first electrode and the second electrode, a pixel defining layer having an opening exposing the first electrode, an auxiliary electrode spaced apart from the opening to cover a portion of the pixel defining layer and connected to the second electrode, a first protection pattern covering the second electrode, and a second protection pattern covering the first protection pattern; and an encapsulation layer covering the display element layer, wherein the first protection pattern and the second protection pattern have stress in directions different from each other.