OLED Pixel Structure for Ink-Jet Printing Alignment
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Solution Overview
Problem
In OLED display manufacturing, the existing ink-jet printing technology faces challenges with aligning nozzles to small sub-pixel regions, leading to uneven thickness and the formation of 'mura' (spots) due to the small spaces, which affects the uniformity and utilization of pixel materials.
Innovation Solution
A pixel structure is designed with sub-pixel regions grouped together, allowing for the formation of sub-pixels integrally, with anode and cathode conductive layers separated and surrounded by insulation layers, and using hydrophobic oleophobic materials to improve alignment and prevent short circuits, enabling easier and more precise injection of hole, luminous, and electron materials using ink-jet printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sub-pixel regions are made small to increase resolution, then the display resolution is improved, but the nozzle alignment becomes difficult and material uniformity deteriorates
Solution Approach 1:
The sub-pixel region is divided into a first sub-pixel region and a second sub-pixel region, with the anode conductive layer segmented into corresponding first and second portions. This segmentation allows the ink-jet printing nozzle to align with and deposit materials into separate, larger target areas, improving manufacturing precision while maintaining high display resolution through the integrated pixel structure.
2Quantity of substance
If the sub-pixel region space is small to increase pixel density, then the pixel density is improved, but the material thickness uniformity deteriorates due to overflow
Solution Approach 1:
The sub-pixel region is segmented into first and second sub-pixel regions with corresponding anode conductive layer portions. This segmentation increases the total target area for material deposition, allowing better control over material distribution and thickness uniformity while maintaining high pixel density through the integrated pixel structure.
Solution Approach 2:
The insulation layer is selectively disposed at adjacent positions of different anode conductive layers to prevent short circuits, while the anode conductive layers themselves are separated within the sub-pixel region. This local differentiation of properties (insulation vs. conduction) enables precise control over material deposition and electrical isolation, improving both thickness uniformity and pixel density.
3Reliability
If the anode conductive layers are separated to prevent short circuits, then the electrical isolation is improved, but the device complexity increases
Solution Approach 1:
The insulation layer is selectively applied only at adjacent positions of different anode conductive layers where short circuits could occur, rather than throughout the entire structure. This localized insulation approach maintains electrical isolation and reliability while minimizing the addition of complex structural elements.
Solution Approach 2:
The first and second anode conductive layers are disposed within the same sub-pixel region and are electrically connected to form a unified anode structure. This merging approach simplifies the overall device structure by integrating multiple conductive layers into a single functional unit, reducing complexity while maintaining electrical isolation where needed.
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 approach enhances the uniformity of sub-pixel thickness, reduces the occurrence of 'mura', and improves material utilization, facilitating the production of OLED display panels with higher resolution.
Implementation Method 1
a nozzle of an ink-jet printer is arranged toward the slots, which drops pixel material into each of the sub-pixel regions
Implementation Method 2
providing a plurality of slots spaced from each other on the substrate... using hydrophobic oleophobic materials to improve alignment and prevent short circuits
Data Source
AI summary
A pixel structure of an organic light emitting diode (OLED) display panel and a manufacturing method thereof are disclosed. The pixel structure comprises a pixel region, anode conductive layers, pixel units, and a cathode conductive layer. The pixel region comprises sub-pixel regions arranged in sequence, at least two adjacent sub-pixel regions defined as a sub-pixel region group are disposed integrally. The anode conductive layers are disposed in the sub-pixel regions respectively, and separated from each other. The cathode conductive layer is electrically connected with the anode conductive layers to control the pixel units. Each of the pixel units comprises sub-pixels and is disposed in the pixel region. Each of the sub-pixels is disposed in one of the sub-pixel regions. The sub-pixels are formed integrally and have a same color in the sub-pixel region group. The pixel unit comprises a hole injection layer, a luminous layer and an electron injection layer.