Asymmetric Insulating Layer for OLED Pixel Definition
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Solution Overview
Problem
Conventional display devices face challenges in achieving higher pixel density and luminance due to thin film thickness issues in organic electroluminescent layers, leading to reduced luminous efficiency and shorter lifespan, as well as color shifts caused by uneven film deposition around the edges of the pixel regions.
Innovation Solution
A display device design featuring an insulating layer with varying widths and orientations within the pixel region, where the first extending portion is narrower than the second extending portion, optimizing the vapor deposition process to minimize thin film regions and enhance uniformity of the organic electroluminescent layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bank width is increased to prevent thin film formation in the light emitting region, then luminous efficiency is maintained, but the space between pixels is widened and pixel definition is reduced
Solution Approach 1:
The insulating layer is designed with different widths at different locations: a first width at the first side and a second width at the second side, where the second width is greater than the first width. This local variation in dimensions allows the structure to prevent thin film formation where needed while minimizing space occupation in other areas, thereby maintaining both luminous efficiency and pixel definition.
Solution Approach 2:
The insulating layer employs an asymmetric width configuration where the width varies between different sides of the pixel region. Specifically, the insulating layer has a greater width at the second side compared to the first side, creating an asymmetric profile that optimizes both film thickness uniformity and space utilization for higher pixel density.
2Manufacturing precision
If the bank width is increased to ensure uniform film thickness, then color shift is prevented, but the pixel area is reduced and luminance is limited
Solution Approach 1:
The insulating layer width is locally optimized by having different widths at different sides, allowing sufficient coverage to ensure uniform film thickness and prevent color shift only where the vapor deposition shadow effect occurs, while minimizing the overall space occupied to maximize pixel area and luminance.
Solution Approach 2:
The asymmetric width configuration of the insulating layer ensures adequate film thickness uniformity at critical regions where shadow effects are most pronounced, while reducing the width at other regions to maximize the overall pixel area available for light emission.
3Manufacturing precision
If the vapor deposition mask opening is reduced to improve pixel density, then definition is enhanced, but thin film regions are more likely to form at the opening edges
Solution Approach 1:
The insulating layer provides localized protection at its edges, particularly at the second side with greater width, to compensate for the thin film formation tendency at vapor deposition mask opening edges. This allows smaller mask openings for higher pixel density while preventing thin film defects through the extended insulating layer coverage.
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 allows for a higher opening ratio and pixel definition without compromising luminous efficiency, reducing the space between pixels and minimizing the formation of thin film regions that could cause electric current concentration and color shifts.
Implementation Method 1
The organic electroluminescent layer is formed by vapor deposition. Specifically, a material that serves as the organic electroluminescent layer is discharged from a line source as a vapor deposition source through a vapor deposition mask in which an opening is formed
Data Source
AI summary
A display device includes: an insulating layer defining a pixel region with a first extending portion and a second extending portion, the first extending portion extending in a direction along a first side of the pixel region, the second extending portion extending in a direction along a second side of the pixel region, the second side crossing the first side; and an organic electroluminescent layer formed in the pixel region, on the first extending portion, and on the second extending portion. A width of the first extending portion in a plan view is smaller than a width of the second extending portion.