OLED Barrier Wall Height Variation for Inkjet Uniformity
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Solution Overview
Problem
The inkjet-printed method for producing OLEDs faces challenges with uneven film thickness of pixel units, making it difficult to achieve uniformity in large-size OLED production.
Innovation Solution
A display panel design featuring a pixel definition layer with specific barrier walls, including first and second barrier walls of varying heights, and spacing barrier walls, which define openings for pixel units and control the flow and diffusion of inkjet-printed solutions to ensure uniform film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inkjet-printed method is used to produce OLEDs, then the film formation speed and material utilization rate are improved, but the film thickness uniformity of pixel units deteriorates
Solution Approach 1:
The pixel definition layer is designed with different barrier wall heights in different regions: edge barrier walls and separation barrier walls are higher than intermediate barrier walls. This local differentiation controls the flow and diffusion of inkjet-printed solutions, ensuring uniform film thickness across the substrate while maintaining high production efficiency.
Solution Approach 2:
The pixel definition layer is segmented into multiple functional components: edge barrier walls at the substrate edges, separation barrier walls between color regions, and intermediate barrier walls between adjacent pixel units. This segmentation allows precise control of material flow in different areas, achieving uniform film thickness without compromising film formation speed.
2Reliability
If the evaporation method is used for film formation, then the process maturity for small-size OLEDs is improved, but the material utilization rate and suitability for large-size production deteriorate
Solution Approach 1:
The patent replaces the evaporation method (physical vapor deposition) with an inkjet printing method (direct liquid deposition). The inkjet printing method deposits organic electroluminescent materials in liquid form directly onto the substrate, achieving near 100% material utilization rate compared to the low material utilization rate of evaporation methods, while enabling large-size OLED production.
3Manufacturing precision
If higher barrier walls are used at edges and separations, then the film thickness uniformity and color separation are improved, but the device structure complexity increases
Solution Approach 1:
The pixel definition layer uses locally differentiated barrier wall heights: higher edge barrier walls (50-200 nm) and separation barrier walls (50-200 nm) at critical locations, and lower intermediate barrier walls (20-100 nm) in regular areas. This localized structural variation achieves superior film thickness uniformity and color separation while minimizing overall structural complexity.
Data Source
AI summary
A display panel, a manufacturing method, and a display device are provided. The display panel includes a substrate and a pixel definition layer. The pixel definition layer includes multiple first barrier walls extending along a first direction and arranged along a second direction and multiple second barrier walls extending along the second direction and arranged along the first direction. The first direction and the second direction intersect. The first barrier walls include two edge barrier walls at two edges along the second direction, multiple intermediate barrier walls between the two edge barrier walls, and two separation barrier walls between the two edge barrier walls and respectively on two sides of the intermediate barrier walls along the second direction. The heights of the second barrier walls, the edge barrier walls and the separation barrier walls each is greater than the height of the intermediate barrier wall.