Inclined Mask Coating for OLED Pixel Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for fabricating organic electroluminescence display devices face challenges in achieving uniform coating of organic electroluminescence layers across pixel regions, particularly in delta and PenTile arrangements, leading to variations in layer thickness and inefficiencies in the coating process.
Innovation Solution
A method involving a mask with inclined surfaces and openings is used to precisely coat organic electroluminescence material onto pixel regions, where the solution is ejected along a straight line between pixel columns, ensuring uniform distribution and preventing accumulation on partition walls, combined with lyophilization and liquid repellent processes to enhance coating uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional nozzle printing process is used to form organic EL layer, then the coating process can be performed, but uniform coating across pixel regions is difficult to achieve and layer thickness varies
Solution Approach 1:
The mask is divided into multiple inclined surfaces (first inclined surfaces and second inclined surfaces) that guide the solution flow into different pixel columns. This segmentation allows the solution to be distributed uniformly across multiple pixel regions through separate flow paths, resolving the contradiction between achieving uniform coating and maintaining simple structure.
Solution Approach 2:
The mask transitions from a conventional flat structure to a three-dimensional structure with inclined surfaces. This dimensional change enables the mask to actively guide solution flow directionally into pixel columns, improving coating uniformity while maintaining manufacturing feasibility through standard fabrication processes.
2Productivity
If solution is ejected at high speed to increase productivity, then coating efficiency improves, but solution accumulates on partition walls causing non-uniform distribution
Solution Approach 1:
The inclined surfaces act as intermediary flow guides between the ejected solution and the pixel regions. These surfaces redirect the high-speed solution flow away from partition walls and into the pixel columns, allowing high productivity to be maintained while achieving uniform distribution through the mediating effect of the inclined geometry.
3Manufacturing precision
If multiple coating stages are used to improve uniformity, then layer thickness uniformity improves, but fabrication process becomes more complex and time-consuming
Solution Approach 1:
The inclined surfaces are pre-formed on the mask before the coating process begins. This preliminary structural preparation enables single-stage uniform coating by pre-establishing the solution flow distribution paths, eliminating the need for multiple coating stages and reducing fabrication time while maintaining high uniformity.
4Ease of manufacture
If a simple flat mask is used, then manufacturing is easier, but solution distribution across pixel columns is non-uniform
Solution Approach 1:
The mask geometry parameters are changed from flat to inclined surfaces with specific angles and extensions. These parameter changes improve solution distribution uniformity while maintaining ease of manufacture because the inclined surfaces can be fabricated using standard photolithography and etching processes commonly used in display device manufacturing.
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 simplifies the fabrication process, reduces the number of stages, and achieves improved uniformity of the organic electroluminescence layer thickness across pixel regions, regardless of the pixel arrangement, thereby enhancing the overall efficiency and precision of the coating process.
Implementation Method 1
evaporating solvent from the solution to form an organic electroluminescence layer
Implementation Method 2
performing a lyophilization process on the first electrode, the lyophilization process including an UV ozone treatment or an oxygen plasma treatment
Implementation Method 3
The mask may include a surface that is treated by a liquid repellent process
Data Source
AI summary
A method of fabricating an organic electroluminescence display device includes providing a substrate including a plurality of pixel regions, first electrodes, and a partition wall, the pixel regions including two pixel columns, providing a mask including openings and first inclined surfaces, the openings being at positions corresponding to the two pixel columns, each of the first inclined surfaces being inclined toward one of the openings and including a portion extending to a region between the two pixel columns, positioning the mask such that each of the openings faces a portion of one of the pixel regions, dropping a solution containing an organic electroluminescence material onto the first inclined surfaces such that the solution is supplied onto the first electrodes through the openings to coat the first electrodes, evaporating solvent from the solution to form an organic electroluminescence layer, and forming a second electrode on the organic electroluminescence layer.