OLED Spacer Bump Geometry for High Pixel Density Control
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Solution Overview
Problem
Current organic light emitting display technologies face challenges in achieving high pixel density due to limitations in mask design, where critical dimensions cannot be smaller than 100 microns, making it difficult to produce displays with pixel densities above 800 ppi.
Innovation Solution
A light emitting device with a substrate and a light emitting layer featuring a spacer with a curved surface bump that separates pixels, allowing for precise control of pixel size and density, including the use of fluorine-rich regions and asymmetric electrode coverage, enabling pixel sizes under 10 microns and thus higher pixel densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mask-based coating method is used, then manufacturing process is simple, but pixel density cannot exceed 800 ppi due to minimum critical dimension of 100 microns
Solution Approach 1:
The device is divided into multiple light emitting pixels with individual electrodes, where each pixel is separated by a spacer structure. This segmentation allows precise control of pixel dimensions and spacing, enabling pixel densities exceeding 1000 ppi while maintaining manufacturability through modular construction.
Solution Approach 2:
The spacer structure features a curved surface with varying radius of curvature, creating different local geometries. The bump portion of the spacer provides asymmetric landing on adjacent electrodes with different overlap widths, allowing local optimization of pixel characteristics for high-density displays.
2Productivity
If pixel size is reduced to increase density, then pixel density increases, but manufacturing precision requirements become more stringent
Solution Approach 1:
The spacer structure is formed beforehand with a predetermined curved surface geometry and bump configuration. This preliminary structuring establishes fixed reference features that guide subsequent electrode and light emitting material deposition, ensuring consistent pixel dimensions and spacing even at reduced pixel sizes below 10 microns.
Solution Approach 2:
The curved surface of the spacer has a varying radius of curvature, and the bump dimensions are specifically optimized to create asymmetric overlap regions. By adjusting these geometric parameters, the invention achieves precise pixel size control and spacing uniformity, enabling high pixel density without proportionally increasing manufacturing precision requirements.
3Adaptability or versatility
If asymmetric overlap width is used for different pixel types, then wavelength spectrum control is improved, but device complexity increases
Solution Approach 1:
The spacer structure incorporates an asymmetric bump that creates different overlap widths between the spacer and adjacent electrodes for different pixel types. This asymmetry enables independent optimization of light emitting characteristics for red, green, and blue pixels, achieving precise wavelength spectrum control while using a single unified spacer design rather than separate structures for each pixel type.
Solution Approach 2:
The single spacer structure with curved surface and bump serves multiple functions: it separates adjacent pixels, defines pixel boundaries, controls overlap width for wavelength tuning, and provides mechanical support. This multi-functionality achieves wavelength spectrum control across different pixel types without increasing overall device complexity.
Data Source
AI summary
A light emitting device includes a substrate and a light emitting layer over the substrate, the light emitting layer. The light emitting layer has a light emitting pixel array including a plurality of light emitting pixels and a spacer. The spacer is configured to separating the plurality of light emitting pixels. Each light emitting pixel has a light emitting material and an electrode between the light emitting material and the substrate. The spacer has a bump having a curved surface extruding away from the substrate, and the bump covers a peripheral region of the electrode.